linux

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 Based on 1 normalized pattern(s): this file is released under the gplv2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 68 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Armijn Hemel <armijn@tjaldur.nl> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190531190114.292346262@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2019-06-01 10:08:42 +02:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: misc preparations for nommu support Make the following misc preparations for percpu nommu support. * Remove refernces to vmalloc in common comments as nommu percpu won't use it. * Rename chunk->vms to chunk->data and make it void *. Its use is determined by chunk management implementation. * Relocate utility functions and add __maybe_unused to functions which might not be used by different chunk management implementations. This patch doesn't cause any functional change. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: update header to contain bitmap allocator explanation. The other patches contain a lot of information, so adding this information in a separate patch. It adds my copyright and a brief explanation of how the bitmap allocator works. There is a minor typo as well in the prior explanation so that is fixed. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:20 -04:00

percpu: update copyright emails to dennis@kernel.org Currently there are 3 emails tied to me in the kernel tree, I'd rather dennis@kernel.org be the only one. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2020-04-01 10:07:48 -07:00

percpu: update header to contain bitmap allocator explanation. The other patches contain a lot of information, so adding this information in a separate patch. It adds my copyright and a brief explanation of how the bitmap allocator works. There is a minor typo as well in the prior explanation so that is fixed. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:20 -04:00

percpu: update the header comment and pcpu_build_alloc_info comments The header comment for percpu memory is a little hard to parse and is not super clear about how the first chunk is managed. This adds a little more clarity to the situation. There is also quite a bit of tricky logic in the pcpu_build_alloc_info. This adds a restructure of a comment to add a little more information. Unfortunately, you will still have to piece together a handful of other comments too, but should help direct you to the meaningful comments. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-15 22:23:09 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: update the header comment and pcpu_build_alloc_info comments The header comment for percpu memory is a little hard to parse and is not super clear about how the first chunk is managed. This adds a little more clarity to the situation. There is also quite a bit of tricky logic in the pcpu_build_alloc_info. This adds a restructure of a comment to add a little more information. Unfortunately, you will still have to piece together a handful of other comments too, but should help direct you to the meaningful comments. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-15 22:23:09 -04:00

percpu: update header to contain bitmap allocator explanation. The other patches contain a lot of information, so adding this information in a separate patch. It adds my copyright and a brief explanation of how the bitmap allocator works. There is a minor typo as well in the prior explanation so that is fixed. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:20 -04:00

percpu: update the header comment and pcpu_build_alloc_info comments The header comment for percpu memory is a little hard to parse and is not super clear about how the first chunk is managed. This adds a little more clarity to the situation. There is also quite a bit of tricky logic in the pcpu_build_alloc_info. This adds a restructure of a comment to add a little more information. Unfortunately, you will still have to piece together a handful of other comments too, but should help direct you to the meaningful comments. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-15 22:23:09 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: update header to contain bitmap allocator explanation. The other patches contain a lot of information, so adding this information in a separate patch. It adds my copyright and a brief explanation of how the bitmap allocator works. There is a minor typo as well in the prior explanation so that is fixed. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:20 -04:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: update header to contain bitmap allocator explanation. The other patches contain a lot of information, so adding this information in a separate patch. It adds my copyright and a brief explanation of how the bitmap allocator works. There is a minor typo as well in the prior explanation so that is fixed. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:20 -04:00

percpu: update the header comment and pcpu_build_alloc_info comments The header comment for percpu memory is a little hard to parse and is not super clear about how the first chunk is managed. This adds a little more clarity to the situation. There is also quite a bit of tricky logic in the pcpu_build_alloc_info. This adds a restructure of a comment to add a little more information. Unfortunately, you will still have to piece together a handful of other comments too, but should help direct you to the meaningful comments. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-15 22:23:09 -04:00

scripts/spelling.txt: add "followings" pattern and fix typo instances Fix typos and add the following to the scripts/spelling.txt: followings||following While we are here, add a missing colon in the boilerplate in DT binding documents. The "you SoC" in allwinner,sunxi-pinctrl.txt was fixed as well. I reworded "as the followings:" to "as follows:" for drivers/usb/gadget/udc/renesas_usb3.c. Link: http://lkml.kernel.org/r/1481573103-11329-32-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2017-02-27 14:29:56 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: make x86 addr <-> pcpu ptr conversion macros generic Impact: generic addr <-> pcpu ptr conversion macros There's nothing arch specific about x86 __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr(). With proper __per_cpu_load and __per_cpu_start defined, they'll do the right thing regardless of actual layout. Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c and allow archs to override it as necessary. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

mm: percpu: use pr_fmt to prefix output Use the normal mechanism to make the logging output consistently "percpu:" instead of a mix of "PERCPU:" and "percpu:" Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:53 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: reduce the number of cpu distance comparisons To build group_map[] and group_cnt[], we find out which group CPUs belong to by comparing the distance of the cpu. However, this includes cases where comparisons are not required. This patch uses a bitmap to record CPUs that is not classified in the group. CPUs that we know which group they belong to should be cleared from the bitmap. In result, we can reduce the number of unnecessary comparisons. Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: added cpumask_clear() call and #include cpumask.h.]

2020-10-30 10:38:20 +09:00

mm: remove include/linux/bootmem.h Move remaining definitions and declarations from include/linux/bootmem.h into include/linux/memblock.h and remove the redundant header. The includes were replaced with the semantic patch below and then semi-automated removal of duplicated '#include <linux/memblock.h> @@ @@ - #include <linux/bootmem.h> + #include <linux/memblock.h> [sfr@canb.auug.org.au: dma-direct: fix up for the removal of linux/bootmem.h] Link: http://lkml.kernel.org/r/20181002185342.133d1680@canb.auug.org.au [sfr@canb.auug.org.au: powerpc: fix up for removal of linux/bootmem.h] Link: http://lkml.kernel.org/r/20181005161406.73ef8727@canb.auug.org.au [sfr@canb.auug.org.au: x86/kaslr, ACPI/NUMA: fix for linux/bootmem.h removal] Link: http://lkml.kernel.org/r/20181008190341.5e396491@canb.auug.org.au Link: http://lkml.kernel.org/r/1536927045-23536-30-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Zankel <chris@zankel.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Ingo Molnar <mingo@redhat.com> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ley Foon Tan <lftan@altera.com> Cc: Mark Salter <msalter@redhat.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Serge Semin <fancer.lancer@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2018-10-30 15:09:49 -07:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: teach large page allocator about NUMA Large page first chunk allocator is primarily used for NUMA machines; however, its NUMA handling is extremely simplistic. Regardless of their proximity, each cpu is put into separate large page just to return most of the allocated space back wasting large amount of vmalloc space and increasing cache footprint. This patch teachs NUMA details to large page allocator. Given processor proximity information, pcpu_lpage_build_unit_map() will find fitting cpu -> unit mapping in which cpus in LOCAL_DISTANCE share the same large page and not too much virtual address space is wasted. This greatly reduces the unit and thus chunk size and wastes much less address space for the first chunk. For example, on 4/4 NUMA machine, the original code occupied 16MB of virtual space for the first chunk while the new code only uses 4MB - one 2MB page for each node. [ Impact: much better space efficiency on NUMA machines ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jan Beulich <JBeulich@novell.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

kmemleak: Handle percpu memory allocation This patch adds kmemleak callbacks from the percpu allocator, reducing a number of false positives caused by kmemleak not scanning such memory blocks. The percpu chunks are never reported as leaks because of current kmemleak limitations with the __percpu pointer not pointing directly to the actual chunks. Reported-by: Huajun Li <huajun.li.lee@gmail.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2011-09-26 17:12:53 +01:00

percpu: include linux/sched.h for cond_resched() microblaze build broke due to missing declaration of the cond_resched() invocation added recently. Let's include linux/sched.h explicitly. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: kbuild test robot <fengguang.wu@intel.com>

2018-03-14 08:27:26 -07:00

percpu: make pcpu_alloc() aware of current gfp context Since 5.7-rc1, on btrfs we have a percpu counter initialization for which we always pass a GFP_KERNEL gfp_t argument (this happens since commit 2992df73268f78 ("btrfs: Implement DREW lock")). That is safe in some contextes but not on others where allowing fs reclaim could lead to a deadlock because we are either holding some btrfs lock needed for a transaction commit or holding a btrfs transaction handle open. Because of that we surround the call to the function that initializes the percpu counter with a NOFS context using memalloc_nofs_save() (this is done at btrfs_init_fs_root()). However it turns out that this is not enough to prevent a possible deadlock because percpu_alloc() determines if it is in an atomic context by looking exclusively at the gfp flags passed to it (GFP_KERNEL in this case) and it is not aware that a NOFS context is set. Because percpu_alloc() thinks it is in a non atomic context it locks the pcpu_alloc_mutex. This can result in a btrfs deadlock when pcpu_balance_workfn() is running, has acquired that mutex and is waiting for reclaim, while the btrfs task that called percpu_counter_init() (and therefore percpu_alloc()) is holding either the btrfs commit_root semaphore or a transaction handle (done fs/btrfs/backref.c: iterate_extent_inodes()), which prevents reclaim from finishing as an attempt to commit the current btrfs transaction will deadlock. Lockdep reports this issue with the following trace: ====================================================== WARNING: possible circular locking dependency detected 5.6.0-rc7-btrfs-next-77 #1 Not tainted ------------------------------------------------------ kswapd0/91 is trying to acquire lock: ffff8938a3b3fdc8 (&delayed_node->mutex){+.+.}, at: __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] but task is already holding lock: ffffffffb4f0dbc0 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (fs_reclaim){+.+.}: fs_reclaim_acquire.part.0+0x25/0x30 __kmalloc+0x5f/0x3a0 pcpu_create_chunk+0x19/0x230 pcpu_balance_workfn+0x56a/0x680 process_one_work+0x235/0x5f0 worker_thread+0x50/0x3b0 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 -> #3 (pcpu_alloc_mutex){+.+.}: __mutex_lock+0xa9/0xaf0 pcpu_alloc+0x480/0x7c0 __percpu_counter_init+0x50/0xd0 btrfs_drew_lock_init+0x22/0x70 [btrfs] btrfs_get_fs_root+0x29c/0x5c0 [btrfs] resolve_indirect_refs+0x120/0xa30 [btrfs] find_parent_nodes+0x50b/0xf30 [btrfs] btrfs_find_all_leafs+0x60/0xb0 [btrfs] iterate_extent_inodes+0x139/0x2f0 [btrfs] iterate_inodes_from_logical+0xa1/0xe0 [btrfs] btrfs_ioctl_logical_to_ino+0xb4/0x190 [btrfs] btrfs_ioctl+0x165a/0x3130 [btrfs] ksys_ioctl+0x87/0xc0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x5c/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&fs_info->commit_root_sem){++++}: down_write+0x38/0x70 btrfs_cache_block_group+0x2ec/0x500 [btrfs] find_free_extent+0xc6a/0x1600 [btrfs] btrfs_reserve_extent+0x9b/0x180 [btrfs] btrfs_alloc_tree_block+0xc1/0x350 [btrfs] alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs] __btrfs_cow_block+0x122/0x5a0 [btrfs] btrfs_cow_block+0x106/0x240 [btrfs] commit_cowonly_roots+0x55/0x310 [btrfs] btrfs_commit_transaction+0x509/0xb20 [btrfs] sync_filesystem+0x74/0x90 generic_shutdown_super+0x22/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 [btrfs] deactivate_locked_super+0x31/0x70 cleanup_mnt+0x100/0x160 task_work_run+0x93/0xc0 exit_to_usermode_loop+0xf9/0x100 do_syscall_64+0x20d/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&space_info->groups_sem){++++}: down_read+0x3c/0x140 find_free_extent+0xef6/0x1600 [btrfs] btrfs_reserve_extent+0x9b/0x180 [btrfs] btrfs_alloc_tree_block+0xc1/0x350 [btrfs] alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs] __btrfs_cow_block+0x122/0x5a0 [btrfs] btrfs_cow_block+0x106/0x240 [btrfs] btrfs_search_slot+0x50c/0xd60 [btrfs] btrfs_lookup_inode+0x3a/0xc0 [btrfs] __btrfs_update_delayed_inode+0x90/0x280 [btrfs] __btrfs_commit_inode_delayed_items+0x81f/0x870 [btrfs] __btrfs_run_delayed_items+0x8e/0x180 [btrfs] btrfs_commit_transaction+0x31b/0xb20 [btrfs] iterate_supers+0x87/0xf0 ksys_sync+0x60/0xb0 __ia32_sys_sync+0xa/0x10 do_syscall_64+0x5c/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&delayed_node->mutex){+.+.}: __lock_acquire+0xef0/0x1c80 lock_acquire+0xa2/0x1d0 __mutex_lock+0xa9/0xaf0 __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] btrfs_evict_inode+0x40d/0x560 [btrfs] evict+0xd9/0x1c0 dispose_list+0x48/0x70 prune_icache_sb+0x54/0x80 super_cache_scan+0x124/0x1a0 do_shrink_slab+0x176/0x440 shrink_slab+0x23a/0x2c0 shrink_node+0x188/0x6e0 balance_pgdat+0x31d/0x7f0 kswapd+0x238/0x550 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 other info that might help us debug this: Chain exists of: &delayed_node->mutex --> pcpu_alloc_mutex --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(pcpu_alloc_mutex); lock(fs_reclaim); lock(&delayed_node->mutex); *** DEADLOCK *** 3 locks held by kswapd0/91: #0: (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 #1: (shrinker_rwsem){++++}, at: shrink_slab+0x12f/0x2c0 #2: (&type->s_umount_key#43){++++}, at: trylock_super+0x16/0x50 stack backtrace: CPU: 1 PID: 91 Comm: kswapd0 Not tainted 5.6.0-rc7-btrfs-next-77 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0x8f/0xd0 check_noncircular+0x170/0x190 __lock_acquire+0xef0/0x1c80 lock_acquire+0xa2/0x1d0 __mutex_lock+0xa9/0xaf0 __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] btrfs_evict_inode+0x40d/0x560 [btrfs] evict+0xd9/0x1c0 dispose_list+0x48/0x70 prune_icache_sb+0x54/0x80 super_cache_scan+0x124/0x1a0 do_shrink_slab+0x176/0x440 shrink_slab+0x23a/0x2c0 shrink_node+0x188/0x6e0 balance_pgdat+0x31d/0x7f0 kswapd+0x238/0x550 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 This could be fixed by making btrfs pass GFP_NOFS instead of GFP_KERNEL to percpu_counter_init() in contextes where it is not reclaim safe, however that type of approach is discouraged since memalloc_[nofs|noio]_save() were introduced. Therefore this change makes pcpu_alloc() look up into an existing nofs/noio context before deciding whether it is in an atomic context or not. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Link: http://lkml.kernel.org/r/20200430164356.15543-1-fdmanana@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-05-07 18:36:10 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: make x86 addr <-> pcpu ptr conversion macros generic Impact: generic addr <-> pcpu ptr conversion macros There's nothing arch specific about x86 __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr(). With proper __per_cpu_load and __per_cpu_start defined, they'll do the right thing regardless of actual layout. Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c and allow archs to override it as necessary. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: Fix kdump failure if booted with percpu_alloc=page o kdump functionality reserves a per cpu area at boot time and exports the physical address of that area to user space through sys interface. This area stores some dump related information like cpu register states etc at the time of crash. o We were assuming that per cpu area always come from linearly mapped meory region and using __pa() to determine physical address. With percpu_alloc=page, per cpu area can come from vmalloc region also and __pa() breaks. o This patch implments a new function to convert per cpu address to physical address. Before the patch, crash_notes addresses looked as follows. cpu0 60fffff49800 cpu1 60fffff60800 cpu2 60fffff77800 These are bogus phsyical addresses. After the patch, address are following. cpu0 13eb44000 cpu1 13eb43000 cpu2 13eb42000 cpu3 13eb41000 These look fine. I got 4G of memory and /proc/iomem tell me following. 100000000-13fffffff : System RAM tj: * added missing asm/io.h include reported by Stephen Rothwell * repositioned per_cpu_ptr_phys() in percpu.c and added comment. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au>

2009-11-24 15:50:03 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: add tracepoint support for percpu memory Add support for tracepoints to the following events: chunk allocation, chunk free, area allocation, area free, and area allocation failure. This should let us replay percpu memory requests and evaluate corresponding decisions. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:32 -04:00

percpu: migrate percpu data structures to internal header Migrates pcpu_chunk definition and a few percpu static variables to an internal header file from mm/percpu.c. These will be used with debugfs to expose statistics about percpu memory improving visibility regarding allocations and fragmentation. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:30 -04:00

percpu: fix a comment about the chunks ordering Since the commit 3e54097beb22 ("percpu: manage chunks based on contig_bits instead of free_bytes") chunks are sorted based on the size of the biggest continuous free area instead of the total number of free bytes. Update the corresponding comment to reflect this. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:31 -07:00

2017-07-12 11:27:32 -07:00

percpu: relegate chunks unusable when failing small allocations In certain cases, requestors of percpu memory may want specific alignments. However, it is possible to end up in situations where the contig_hint matches, but the alignment does not. This causes excess scanning of chunks that will fail. To prevent this, if a small allocation fails (< 32B), the chunk is moved to the empty list. Once an allocation is freed from that chunk, it is placed back into rotation. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 09:03:50 -08:00

2017-07-12 11:27:32 -07:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: make x86 addr <-> pcpu ptr conversion macros generic Impact: generic addr <-> pcpu ptr conversion macros There's nothing arch specific about x86 __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr(). With proper __per_cpu_load and __per_cpu_start defined, they'll do the right thing regardless of actual layout. Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c and allow archs to override it as necessary. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: add __percpu sparse annotations to core kernel subsystems Add __percpu sparse annotations to core subsystems. These annotations are to make sparse consider percpu variables to be in a different address space and warn if accessed without going through percpu accessors. This patch doesn't affect normal builds. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-mm@kvack.org Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Eric Biederman <ebiederm@xmission.com>

2010-02-02 14:38:57 +09:00

percpu: make x86 addr <-> pcpu ptr conversion macros generic Impact: generic addr <-> pcpu ptr conversion macros There's nothing arch specific about x86 __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr(). With proper __per_cpu_load and __per_cpu_start defined, they'll do the right thing regardless of actual layout. Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c and allow archs to override it as necessary. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: add __percpu sparse annotations to core kernel subsystems Add __percpu sparse annotations to core subsystems. These annotations are to make sparse consider percpu variables to be in a different address space and warn if accessed without going through percpu accessors. This patch doesn't affect normal builds. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-mm@kvack.org Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Eric Biederman <ebiederm@xmission.com>

2010-02-02 14:38:57 +09:00

percpu: make x86 addr <-> pcpu ptr conversion macros generic Impact: generic addr <-> pcpu ptr conversion macros There's nothing arch specific about x86 __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr(). With proper __per_cpu_load and __per_cpu_start defined, they'll do the right thing regardless of actual layout. Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c and allow archs to override it as necessary. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: make x86 addr <-> pcpu ptr conversion macros generic Impact: generic addr <-> pcpu ptr conversion macros There's nothing arch specific about x86 __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr(). With proper __per_cpu_load and __per_cpu_start defined, they'll do the right thing regardless of actual layout. Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c and allow archs to override it as necessary. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

mark most percpu globals as __ro_after_init Moving pcpu_base_addr to this section comes from PaX where it's part of KERNEXEC. This extends it to the rest of the globals only written by the init code. Signed-off-by: Daniel Micay <danielmicay@gmail.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-05-10 13:36:37 -04:00

percpu: migrate percpu data structures to internal header Migrates pcpu_chunk definition and a few percpu static variables to an internal header file from mm/percpu.c. These will be used with debugfs to expose statistics about percpu memory improving visibility regarding allocations and fragmentation. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:30 -04:00

percpu: make symbol 'pcpu_free_slot' static The sparse tool complains as follows: mm/percpu.c:138:5: warning: symbol 'pcpu_free_slot' was not declared. Should it be static? This symbol is not used outside of percpu.c, so marks it static. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-05-14 06:39:52 +00:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

mark most percpu globals as __ro_after_init Moving pcpu_base_addr to this section comes from PaX where it's part of KERNEXEC. This extends it to the rest of the globals only written by the init code. Signed-off-by: Daniel Micay <danielmicay@gmail.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-05-10 13:36:37 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: fix chunk range calculation Percpu allocator recorded the cpus which map to the first and last units in pcpu_first/last_unit_cpu respectively and used them to determine the address range of a chunk - e.g. it assumed that the first unit has the lowest address in a chunk while the last unit has the highest address. This simply isn't true. Groups in a chunk can have arbitrary positive or negative offsets from the previous one and there is no guarantee that the first unit occupies the lowest offset while the last one the highest. Fix it by actually comparing unit offsets to determine cpus occupying the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu to pcpu_low/high_unit_cpu to avoid confusion. The chunk address range is used to flush cache on vmalloc area map/unmap and decide whether a given address is in the first chunk by per_cpu_ptr_to_phys() and the bug was discovered by invalid per_cpu_ptr_to_phys() translation for crash_note. Kudos to Dave Young for tracking down the problem. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: WANG Cong <xiyou.wangcong@gmail.com> Reported-by: Dave Young <dyoung@redhat.com> Tested-by: Dave Young <dyoung@redhat.com> LKML-Reference: <4EC21F67.10905@redhat.com> Cc: stable @kernel.org

2011-11-18 10:55:35 -08:00

mark most percpu globals as __ro_after_init Moving pcpu_base_addr to this section comes from PaX where it's part of KERNEXEC. This extends it to the rest of the globals only written by the init code. Signed-off-by: Daniel Micay <danielmicay@gmail.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-05-10 13:36:37 -04:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

mark most percpu globals as __ro_after_init Moving pcpu_base_addr to this section comes from PaX where it's part of KERNEXEC. This extends it to the rest of the globals only written by the init code. Signed-off-by: Daniel Micay <danielmicay@gmail.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-05-10 13:36:37 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

mark most percpu globals as __ro_after_init Moving pcpu_base_addr to this section comes from PaX where it's part of KERNEXEC. This extends it to the rest of the globals only written by the init code. Signed-off-by: Daniel Micay <danielmicay@gmail.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-05-10 13:36:37 -04:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: use group information to allocate vmap areas sparsely ai->groups[] contains which units need to be put consecutively and at what offset from the chunk base address. Compile this information into pcpu_group_offsets[] and pcpu_group_sizes[] in pcpu_setup_first_chunk() and use them to allocate sparse vm areas using pcpu_get_vm_areas(). This will be used to allow directly using sparse NUMA memories as percpu areas. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de>

2009-08-14 15:00:52 +09:00

mark most percpu globals as __ro_after_init Moving pcpu_base_addr to this section comes from PaX where it's part of KERNEXEC. This extends it to the rest of the globals only written by the init code. Signed-off-by: Daniel Micay <danielmicay@gmail.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-05-10 13:36:37 -04:00

percpu: use group information to allocate vmap areas sparsely ai->groups[] contains which units need to be put consecutively and at what offset from the chunk base address. Compile this information into pcpu_group_offsets[] and pcpu_group_sizes[] in pcpu_setup_first_chunk() and use them to allocate sparse vm areas using pcpu_get_vm_areas(). This will be used to allow directly using sparse NUMA memories as percpu areas. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de>

2009-08-14 15:00:52 +09:00

percpu: don't put the first chunk in reverse-map rbtree Impact: both first chunks don't use rbtree, no functional change There can be two first chunks - reserved and dynamic with the former one being optional. Dynamic first chunk was linked on reverse-mapping rbtree while the reserved one was mapped manually using the start address and reserved offset limit. This patch makes both first chunks to be looked up manually without using the rbtree. This is to help getting rid of the rbtree. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: rusty@rustcorp.com.au Cc: Paul Mundt <lethal@linux-sh.org> Cc: rmk@arm.linux.org.uk Cc: starvik@axis.com Cc: ralf@linux-mips.org Cc: davem@davemloft.net Cc: cooloney@kernel.org Cc: kyle@mcmartin.ca Cc: matthew@wil.cx Cc: grundler@parisc-linux.org Cc: takata@linux-m32r.org Cc: benh@kernel.crashing.org Cc: rth@twiddle.net Cc: ink@jurassic.park.msu.ru Cc: heiko.carstens@de.ibm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> Cc: Christoph Lameter <cl@linux.com> LKML-Reference: <49D43CEA.3040609@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>

2009-04-02 13:19:54 +09:00

percpu: migrate percpu data structures to internal header Migrates pcpu_chunk definition and a few percpu static variables to an internal header file from mm/percpu.c. These will be used with debugfs to expose statistics about percpu memory improving visibility regarding allocations and fragmentation. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:30 -04:00

percpu: don't put the first chunk in reverse-map rbtree Impact: both first chunks don't use rbtree, no functional change There can be two first chunks - reserved and dynamic with the former one being optional. Dynamic first chunk was linked on reverse-mapping rbtree while the reserved one was mapped manually using the start address and reserved offset limit. This patch makes both first chunks to be looked up manually without using the rbtree. This is to help getting rid of the rbtree. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: rusty@rustcorp.com.au Cc: Paul Mundt <lethal@linux-sh.org> Cc: rmk@arm.linux.org.uk Cc: starvik@axis.com Cc: ralf@linux-mips.org Cc: davem@davemloft.net Cc: cooloney@kernel.org Cc: kyle@mcmartin.ca Cc: matthew@wil.cx Cc: grundler@parisc-linux.org Cc: takata@linux-m32r.org Cc: benh@kernel.crashing.org Cc: rth@twiddle.net Cc: ink@jurassic.park.msu.ru Cc: heiko.carstens@de.ibm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> Cc: Christoph Lameter <cl@linux.com> LKML-Reference: <49D43CEA.3040609@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>

2009-04-02 13:19:54 +09:00

percpu: introduce start_offset to pcpu_chunk The reserved chunk arithmetic uses a global variable pcpu_reserved_chunk_limit that is set in the first chunk init code to hide a portion of the area map. The bitmap allocator to come will eventually move the base_addr up and require both the reserved chunk and static chunk to maintain this offset. pcpu_reserved_chunk_limit is removed and start_offset is added. The first chunk that is circulated and is pcpu_first_chunk serves the dynamic region, the region following the reserved region. The reserved chunk address check will temporarily use the first chunk to identify its address range. A following patch will increase the base_addr and remove this. If there is no reserved chunk, this will check the static region and return false because those values should never be passed into the allocator. Lastly, when linking in the first chunk, make sure to count the right free region for the number of empty populated pages. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:01:59 -04:00

percpu: don't put the first chunk in reverse-map rbtree Impact: both first chunks don't use rbtree, no functional change There can be two first chunks - reserved and dynamic with the former one being optional. Dynamic first chunk was linked on reverse-mapping rbtree while the reserved one was mapped manually using the start address and reserved offset limit. This patch makes both first chunks to be looked up manually without using the rbtree. This is to help getting rid of the rbtree. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: rusty@rustcorp.com.au Cc: Paul Mundt <lethal@linux-sh.org> Cc: rmk@arm.linux.org.uk Cc: starvik@axis.com Cc: ralf@linux-mips.org Cc: davem@davemloft.net Cc: cooloney@kernel.org Cc: kyle@mcmartin.ca Cc: matthew@wil.cx Cc: grundler@parisc-linux.org Cc: takata@linux-m32r.org Cc: benh@kernel.crashing.org Cc: rth@twiddle.net Cc: ink@jurassic.park.msu.ru Cc: heiko.carstens@de.ibm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> Cc: Christoph Lameter <cl@linux.com> LKML-Reference: <49D43CEA.3040609@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>

2009-04-02 13:19:54 +09:00

percpu: migrate percpu data structures to internal header Migrates pcpu_chunk definition and a few percpu static variables to an internal header file from mm/percpu.c. These will be used with debugfs to expose statistics about percpu memory improving visibility regarding allocations and fragmentation. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:30 -04:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: migrate percpu data structures to internal header Migrates pcpu_chunk definition and a few percpu static variables to an internal header file from mm/percpu.c. These will be used with debugfs to expose statistics about percpu memory improving visibility regarding allocations and fragmentation. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:30 -04:00

percpu: fix synchronization between synchronous map extension and chunk destruction For non-atomic allocations, pcpu_alloc() can try to extend the area map synchronously after dropping pcpu_lock; however, the extension wasn't synchronized against chunk destruction and the chunk might get freed while extension is in progress. This patch fixes the bug by putting most of non-atomic allocations under pcpu_alloc_mutex to synchronize against pcpu_balance_work which is responsible for async chunk management including destruction. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Reported-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: stable@vger.kernel.org # v3.18+ Fixes: 1a4d76076cda ("percpu: implement asynchronous chunk population")

2016-05-25 11:48:25 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: make pcpu_nr_empty_pop_pages per chunk type nr_empty_pop_pages is used to guarantee that there are some free populated pages to satisfy atomic allocations. Accounted and non-accounted allocations are using separate sets of chunks, so both need to have a surplus of empty pages. This commit makes pcpu_nr_empty_pop_pages and the corresponding logic per chunk type. [Dennis] This issue came up as I was reviewing [1] and realized I missed this. Simultaneously, it was reported btrfs was seeing failed atomic allocations in fsstress tests [2] and [3]. [1] https://lore.kernel.org/linux-mm/20210324190626.564297-1-guro@fb.com/ [2] https://lore.kernel.org/linux-mm/20210401185158.3275.409509F4@e16-tech.com/ [3] https://lore.kernel.org/linux-mm/CAL3q7H5RNBjCi708GH7jnczAOe0BLnacT9C+OBgA-Dx9jhB6SQ@mail.gmail.com/ Fixes: 3c7be18ac9a0 ("mm: memcg/percpu: account percpu memory to memory cgroups") Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Roman Gushchin <guro@fb.com> Tested-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:33 -07:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

/proc/meminfo: add percpu populated pages count Currently, percpu memory only exposes allocation and utilization information via debugfs. This more or less is only really useful for understanding the fragmentation and allocation information at a per-chunk level with a few global counters. This is also gated behind a config. BPF and cgroup, for example, have seen an increase in use causing increased use of percpu memory. Let's make it easier for someone to identify how much memory is being used. This patch adds the "Percpu" stat to meminfo to more easily look up how much percpu memory is in use. This number includes the cost for all allocated backing pages and not just insight at the per a unit, per chunk level. Metadata is excluded. I think excluding metadata is fair because the backing memory scales with the numbere of cpus and can quickly outweigh the metadata. It also makes this calculation light. Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2018-08-21 21:53:58 -07:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: rename pcpu_reclaim_work to pcpu_balance_work pcpu_reclaim_work will also be used to populate chunks asynchronously. Rename it to pcpu_balance_work in preparation. pcpu_reclaim() is renamed to pcpu_balance_workfn() and some of its local variables are renamed too. This is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: combine percpu address checks The percpu address checks for the reserved and dynamic region chunks are now specific to each region. The address checking logic can be combined taking advantage of the global references to the dynamic and static region chunks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:06 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: combine percpu address checks The percpu address checks for the reserved and dynamic region chunks are now specific to each region. The address checking logic can be combined taking advantage of the global references to the dynamic and static region chunks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:06 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: combine percpu address checks The percpu address checks for the reserved and dynamic region chunks are now specific to each region. The address checking logic can be combined taking advantage of the global references to the dynamic and static region chunks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:06 -04:00

percpu: factor out pcpu_addr_in_first/reserved_chunk() and update per_cpu_ptr_to_phys() Factor out pcpu_addr_in_first/reserved_chunk() from pcpu_chunk_addr_search() and use it to update per_cpu_ptr_to_phys() such that it handles first chunk differently from the rest. This patch doesn't cause any functional change and is to prepare for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:00 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: combine percpu address checks The percpu address checks for the reserved and dynamic region chunks are now specific to each region. The address checking logic can be combined taking advantage of the global references to the dynamic and static region chunks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:06 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: factor out pcpu_addr_in_first/reserved_chunk() and update per_cpu_ptr_to_phys() Factor out pcpu_addr_in_first/reserved_chunk() from pcpu_chunk_addr_search() and use it to update per_cpu_ptr_to_phys() such that it handles first chunk differently from the rest. This patch doesn't cause any functional change and is to prepare for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:00 +09:00

percpu: combine percpu address checks The percpu address checks for the reserved and dynamic region chunks are now specific to each region. The address checking logic can be combined taking advantage of the global references to the dynamic and static region chunks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:06 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: factor out pcpu_addr_in_first/reserved_chunk() and update per_cpu_ptr_to_phys() Factor out pcpu_addr_in_first/reserved_chunk() from pcpu_chunk_addr_search() and use it to update per_cpu_ptr_to_phys() such that it handles first chunk differently from the rest. This patch doesn't cause any functional change and is to prepare for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:00 +09:00

percpu: remove unit_size power-of-2 restriction Impact: allow unit_size to be arbitrary multiple of PAGE_SIZE In dynamic percpu allocator, there is no reason the unit size should be power of two. Remove the restriction. As non-power-of-two unit size means that empty chunks fall into the same slot index as lightly occupied chunks which is bad for reclaming. Reserve an extra slot for empty chunks. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: clean up size usage Andrew was concerned about the unit of variables named or have suffix size. Every usage in percpu allocator is in bytes but make it super clear by adding comments. While at it, make pcpu_depopulate_chunk() take int @off and @size like everyone else. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-21 16:56:23 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: remove unit_size power-of-2 restriction Impact: allow unit_size to be arbitrary multiple of PAGE_SIZE In dynamic percpu allocator, there is no reason the unit size should be power of two. Remove the restriction. As non-power-of-two unit size means that empty chunks fall into the same slot index as lightly occupied chunks which is bad for reclaming. Reserve an extra slot for empty chunks. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: use pcpu_free_slot instead of pcpu_nr_slots - 1 This prepares for adding a to_depopulate list and sidelined list after the free slot in the set of lists in pcpu_slot. Signed-off-by: Dennis Zhou <dennis@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-18 22:44:16 +00:00

percpu: remove unit_size power-of-2 restriction Impact: allow unit_size to be arbitrary multiple of PAGE_SIZE In dynamic percpu allocator, there is no reason the unit size should be power of two. Remove the restriction. As non-power-of-two unit size means that empty chunks fall into the same slot index as lightly occupied chunks which is bad for reclaming. Reserve an extra slot for empty chunks. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: misc preparations for nommu support Make the following misc preparations for percpu nommu support. * Remove refernces to vmalloc in common comments as nommu percpu won't use it. * Rename chunk->vms to chunk->data and make it void *. Its use is determined by chunk management implementation. * Relocate utility functions and add __maybe_unused to functions which might not be used by different chunk management implementations. This patch doesn't cause any functional change. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: fix first chunk match in per_cpu_ptr_to_phys() per_cpu_ptr_to_phys() determines whether the passed in @addr belongs to the first_chunk or not by just matching the address against the address range of the base unit (unit0, used by cpu0). When an adress from another cpu was passed in, it will always determine that the address doesn't belong to the first chunk even when it does. This makes the function return a bogus physical address which may lead to crash. This problem was discovered by Cliff Wickman while investigating a crash during kdump on a SGI UV system. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Cliff Wickman <cpw@sgi.com> Tested-by: Cliff Wickman <cpw@sgi.com> Cc: stable@kernel.org

2010-06-18 11:44:31 +02:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: factor out pcpu_check_block_hint() Factor out the pcpu_check_block_hint() helper, which will be useful in the future. The new function checks if the allocation can likely fit within the contig hint. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:35 -07:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: use metadata blocks to update the chunk contig hint The largest free region will either be a block level contig hint or an aggregate over the left_free and right_free areas of blocks. This is a much smaller set of free areas that need to be checked than a full traverse. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:18 -04:00

percpu: fix iteration to prevent skipping over block The iterator functions pcpu_next_md_free_region and pcpu_next_fit_region use the block offset to determine if they have checked the area in the prior iteration. However, this causes an issue when the block offset is greater than subsequent block contig hints. If within the iterator it moves to check subsequent blocks, it may fail in the second predicate due to the block offset not being cleared. Thus, this causes the allocator to skip over blocks leading to false failures when allocating from the reserved chunk. While this happens in the general case as well, it will only fail if it cannot allocate a new chunk. This patch resets the block offset to 0 to pass the second predicate when checking subseqent blocks within the iterator function. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reported-and-tested-by: Luis Henriques <lhenriques@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-09-27 16:35:00 -05:00

percpu: use metadata blocks to update the chunk contig hint The largest free region will either be a block level contig hint or an aggregate over the left_free and right_free areas of blocks. This is a much smaller set of free areas that need to be checked than a full traverse. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:18 -04:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

percpu: fix iteration to prevent skipping over block The iterator functions pcpu_next_md_free_region and pcpu_next_fit_region use the block offset to determine if they have checked the area in the prior iteration. However, this causes an issue when the block offset is greater than subsequent block contig hints. If within the iterator it moves to check subsequent blocks, it may fail in the second predicate due to the block offset not being cleared. Thus, this causes the allocator to skip over blocks leading to false failures when allocating from the reserved chunk. While this happens in the general case as well, it will only fail if it cannot allocate a new chunk. This patch resets the block offset to 0 to pass the second predicate when checking subseqent blocks within the iterator function. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reported-and-tested-by: Luis Henriques <lhenriques@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-09-27 16:35:00 -05:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

percpu: use metadata blocks to update the chunk contig hint The largest free region will either be a block level contig hint or an aggregate over the left_free and right_free areas of blocks. This is a much smaller set of free areas that need to be checked than a full traverse. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:18 -04:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

percpu: use metadata blocks to update the chunk contig hint The largest free region will either be a block level contig hint or an aggregate over the left_free and right_free areas of blocks. This is a much smaller set of free areas that need to be checked than a full traverse. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:18 -04:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: rename pcpu_mem_alloc to pcpu_mem_zalloc Currently pcpu_mem_alloc() is implemented always return zeroed memory. So rename it to make user like pcpu_get_pages_and_bitmap() know don't reinit it. Signed-off-by: Bob Liu <lliubbo@gmail.com> Reviewed-by: Pekka Enberg <penberg@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Tejun Heo <tj@kernel.org>

2011-08-04 11:02:33 +02:00

percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: allow limited allocation before slab is online This patch updates percpu allocator such that it can serve limited amount of allocation before slab comes online. This is primarily to allow slab to depend on working percpu allocator. Two parameters, PERCPU_DYNAMIC_EARLY_SIZE and SLOTS, determine how much memory space and allocation map slots are reserved. If this reserved area is exhausted, WARN_ON_ONCE() will trigger and allocation will fail till slab comes online. The following changes are made to implement early alloc. * pcpu_mem_alloc() now checks slab_is_available() * Chunks are allocated using pcpu_mem_alloc() * Init paths make sure ai->dyn_size is at least as large as PERCPU_DYNAMIC_EARLY_SIZE. * Initial alloc maps are allocated in __initdata and copied to kmalloc'd areas once slab is online. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux-foundation.org>

2010-06-27 18:50:00 +02:00

percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

percpu: allow select gfp to be passed to underlying allocators The prior patch added support for passing gfp flags through to the underlying allocators. This patch allows users to pass along gfp flags (currently only __GFP_NORETRY and __GFP_NOWARN) to the underlying allocators. This should allow users to decide if they are ok with failing allocations recovering in a more graceful way. Additionally, gfp passing was done as additional flags in the previous patch. Instead, change this to caller passed semantics. GFP_KERNEL is also removed as the default flag. It continues to be used for internally caused underlying percpu allocations. V2: Removed gfp_percpu_mask in favor of doing it inline. Removed GFP_KERNEL as a default flag for __alloc_percpu_gfp. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:09:58 -06:00

percpu: zero memory more efficiently in mm/percpu.c::pcpu_mem_alloc() Don't do vmalloc() + memset() when vzalloc() will do. tj: dropped unnecessary temp variable ptr. Signed-off-by: Jesper Juhl <jj@chaosbits.net> Signed-off-by: Tejun Heo <tj@kernel.org>

2010-10-30 15:56:54 +02:00

mm: remove the pgprot argument to __vmalloc The pgprot argument to __vmalloc is always PAGE_KERNEL now, so remove it. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Michael Kelley <mikelley@microsoft.com> [hyperv] Acked-by: Gao Xiang <xiang@kernel.org> [erofs] Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Wei Liu <wei.liu@kernel.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Laura Abbott <labbott@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Sakari Ailus <sakari.ailus@linux.intel.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Paul Mackerras <paulus@ozlabs.org> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Will Deacon <will@kernel.org> Link: http://lkml.kernel.org/r/20200414131348.444715-22-hch@lst.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-06-01 21:51:40 -07:00

percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

percpu: rename pcpu_mem_alloc to pcpu_mem_zalloc Currently pcpu_mem_alloc() is implemented always return zeroed memory. So rename it to make user like pcpu_get_pages_and_bitmap() know don't reinit it. Signed-off-by: Bob Liu <lliubbo@gmail.com> Reviewed-by: Pekka Enberg <penberg@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Tejun Heo <tj@kernel.org>

2011-08-04 11:02:33 +02:00

percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

tree wide: use kvfree() than conditional kfree()/vfree() There are many locations that do if (memory_was_allocated_by_vmalloc) vfree(ptr); else kfree(ptr); but kvfree() can handle both kmalloc()ed memory and vmalloc()ed memory using is_vmalloc_addr(). Unless callers have special reasons, we can replace this branch with kvfree(). Please check and reply if you found problems. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Jan Kara <jack@suse.com> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Reviewed-by: Andreas Dilger <andreas.dilger@intel.com> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: David Rientjes <rientjes@google.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Oleg Drokin <oleg.drokin@intel.com> Cc: Boris Petkov <bp@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-01-22 15:11:02 -08:00

percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

tree wide: use kvfree() than conditional kfree()/vfree() There are many locations that do if (memory_was_allocated_by_vmalloc) vfree(ptr); else kfree(ptr); but kvfree() can handle both kmalloc()ed memory and vmalloc()ed memory using is_vmalloc_addr(). Unless callers have special reasons, we can replace this branch with kvfree(). Please check and reply if you found problems. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Jan Kara <jack@suse.com> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Reviewed-by: Andreas Dilger <andreas.dilger@intel.com> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: David Rientjes <rientjes@google.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Oleg Drokin <oleg.drokin@intel.com> Cc: Boris Petkov <bp@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-01-22 15:11:02 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: relegate chunks unusable when failing small allocations In certain cases, requestors of percpu memory may want specific alignments. However, it is possible to end up in situations where the contig_hint matches, but the alignment does not. This causes excess scanning of chunks that will fail. To prevent this, if a small allocation fails (< 32B), the chunk is moved to the empty list. Once an allocation is freed from that chunk, it is placed back into rotation. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 09:03:50 -08:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: relegate chunks unusable when failing small allocations In certain cases, requestors of percpu memory may want specific alignments. However, it is possible to end up in situations where the contig_hint matches, but the alignment does not. This causes excess scanning of chunks that will fail. To prevent this, if a small allocation fails (< 32B), the chunk is moved to the empty list. Once an allocation is freed from that chunk, it is placed back into rotation. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 09:03:50 -08:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: relegate chunks unusable when failing small allocations In certain cases, requestors of percpu memory may want specific alignments. However, it is possible to end up in situations where the contig_hint matches, but the alignment does not. This causes excess scanning of chunks that will fail. To prevent this, if a small allocation fails (< 32B), the chunk is moved to the empty list. Once an allocation is freed from that chunk, it is placed back into rotation. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 09:03:50 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: relegate chunks unusable when failing small allocations In certain cases, requestors of percpu memory may want specific alignments. However, it is possible to end up in situations where the contig_hint matches, but the alignment does not. This causes excess scanning of chunks that will fail. To prevent this, if a small allocation fails (< 32B), the chunk is moved to the empty list. Once an allocation is freed from that chunk, it is placed back into rotation. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 09:03:50 -08:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

2017-07-12 11:27:32 -07:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

2017-07-12 11:27:32 -07:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

2017-07-12 11:27:32 -07:00

percpu: introduce helper to determine if two regions overlap While block hints were always accurate, it's possible when spanning across blocks that we miss updating the chunk's contig_hint. Rather than rely on correctness of the boundaries of hints, do a full overlap comparison. A future patch introduces the scan_hint which makes the contig_hint slightly fuzzy as they can at times be smaller than the actual hint. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-21 15:44:35 -08:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

percpu: introduce helper to determine if two regions overlap While block hints were always accurate, it's possible when spanning across blocks that we miss updating the chunk's contig_hint. Rather than rely on correctness of the boundaries of hints, do a full overlap comparison. A future patch introduces the scan_hint which makes the contig_hint slightly fuzzy as they can at times be smaller than the actual hint. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-21 15:44:35 -08:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

percpu: introduce helper to determine if two regions overlap While block hints were always accurate, it's possible when spanning across blocks that we miss updating the chunk's contig_hint. Rather than rely on correctness of the boundaries of hints, do a full overlap comparison. A future patch introduces the scan_hint which makes the contig_hint slightly fuzzy as they can at times be smaller than the actual hint. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-21 15:44:35 -08:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

percpu: introduce helper to determine if two regions overlap While block hints were always accurate, it's possible when spanning across blocks that we miss updating the chunk's contig_hint. Rather than rely on correctness of the boundaries of hints, do a full overlap comparison. A future patch introduces the scan_hint which makes the contig_hint slightly fuzzy as they can at times be smaller than the actual hint. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-21 15:44:35 -08:00

2017-07-12 11:27:32 -07:00

percpu: move chunk area map extension out of area allocation Impact: code reorganization for later changes Separate out chunk area map extension into a separate function - pcpu_extend_area_map() - and call it directly from pcpu_alloc() such that pcpu_alloc_area() is guaranteed to have enough area map slots on invocation. With this change, pcpu_alloc_area() does only area allocation and the only failure mode is when the chunk doens't have enough room, so there's no need to distinguish it from memory allocation failures. Make it return -1 on such cases instead of hacky -ENOSPC. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: keep track of the best offset for contig hints This patch makes the contig hint starting offset optimization from the previous patch as honest as it can be. For both chunk and block starting offsets, make sure it keeps the starting offset with the best alignment. The block skip optimization is added in a later patch when the pcpu_find_block_fit iterator is swapped in. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:15 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: make pcpu_block_md generic In reality, a chunk is just a block covering a larger number of bits. The hints themselves are one in the same. Rather than maintaining the hints separately, first introduce nr_bits to genericize pcpu_block_update() to correctly maintain block->right_free. The next patch will convert chunk hints to be managed as a pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 09:56:16 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: remember largest area skipped during allocation Percpu allocations attempt to do first fit by scanning forward from the first_free of a block. However, fragmentation from allocation requests can cause holes not seen by block hint update functions. To address this, create a local version of bitmap_find_next_zero_area_off() that remembers the largest area skipped over. The caveat is that it only sees regions skipped over due to not fitting, not regions skipped due to alignment. Prior to updating the scan_hint, a scan backwards is done to try and recover free bits skipped due to alignment. While this can cause scanning to miss earlier possible free areas, smaller allocations will eventually fill those holes due to first fit. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-22 09:03:16 -08:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: use chunk scan_hint to skip some scanning Just like blocks, chunks now maintain a scan_hint. This can be used to skip some scanning by promoting the scan_hint to be the contig_hint. The chunk's scan_hint is primarily updated on the backside and relies on full scanning when a block becomes free or the free region spans across blocks. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:46:48 -08:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: use chunk scan_hint to skip some scanning Just like blocks, chunks now maintain a scan_hint. This can be used to skip some scanning by promoting the scan_hint to be the contig_hint. The chunk's scan_hint is primarily updated on the backside and relies on full scanning when a block becomes free or the free region spans across blocks. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:46:48 -08:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: use chunk scan_hint to skip some scanning Just like blocks, chunks now maintain a scan_hint. This can be used to skip some scanning by promoting the scan_hint to be the contig_hint. The chunk's scan_hint is primarily updated on the backside and relies on full scanning when a block becomes free or the free region spans across blocks. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:46:48 -08:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: use chunk scan_hint to skip some scanning Just like blocks, chunks now maintain a scan_hint. This can be used to skip some scanning by promoting the scan_hint to be the contig_hint. The chunk's scan_hint is primarily updated on the backside and relies on full scanning when a block becomes free or the free region spans across blocks. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:46:48 -08:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

bitmap: genericize percpu bitmap region iterators Bitmaps are fairly popular for their space efficiency, but we don't have generic iterators available. Make percpu's bitmap region iterators available to everyone. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>

2019-12-13 16:22:10 -08:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

bitmap: unify find_bit operations bitmap_for_each_{set,clear}_region() are similar to for_each_bit() macros in include/linux/find.h, but interface and implementation of them are different. This patch adds for_each_bitrange() macros and drops unused bitmap_*_region() API in sake of unification. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC

2021-08-14 14:17:11 -07:00

percpu: use block scan_hint to only scan forward Blocks now remember the latest scan_hint. This can be used on the allocation path as when a contig_hint is broken, we can promote the scan_hint to the contig_hint and scan forward from there. This works because pcpu_block_refresh_hint() is only called on the allocation path while block free regions are updated manually in pcpu_block_update_hint_free(). Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-25 14:10:15 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: use block scan_hint to only scan forward Blocks now remember the latest scan_hint. This can be used on the allocation path as when a contig_hint is broken, we can promote the scan_hint to the contig_hint and scan forward from there. This works because pcpu_block_refresh_hint() is only called on the allocation path while block free regions are updated manually in pcpu_block_update_hint_free(). Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-25 14:10:15 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

bitmap: unify find_bit operations bitmap_for_each_{set,clear}_region() are similar to for_each_bit() macros in include/linux/find.h, but interface and implementation of them are different. This patch adds for_each_bitrange() macros and drops unused bitmap_*_region() API in sake of unification. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC

2021-08-14 14:17:11 -07:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: update alloc path to only scan if contig hints are broken Metadata is kept per block to keep track of where the contig hints are. Scanning can be avoided when the contig hints are not broken. In that case, left and right contigs have to be managed manually. This patch changes the allocation path hint updating to only scan when contig hints are broken. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:16 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

mm/percpu: add comment to state the empty populated pages accounting When allocating an area from a chunk, pcpu_block_update_hint_alloc() is called to update chunk metadata, including chunk's and global nr_empty_pop_pages. However, if the allocation is not atomic, some blocks may not be populated with pages yet, while we still subtract the number here. The number of pages will be added back with pcpu_chunk_populated() when populating pages. Adding code comment to make that more understandable. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2022-10-25 11:45:16 +08:00

percpu: update alloc path to only scan if contig hints are broken Metadata is kept per block to keep track of where the contig hints are. Scanning can be avoided when the contig hints are not broken. In that case, left and right contigs have to be managed manually. This patch changes the allocation path hint updating to only scan when contig hints are broken. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:16 -04:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: introduce helper to determine if two regions overlap While block hints were always accurate, it's possible when spanning across blocks that we miss updating the chunk's contig_hint. Rather than rely on correctness of the boundaries of hints, do a full overlap comparison. A future patch introduces the scan_hint which makes the contig_hint slightly fuzzy as they can at times be smaller than the actual hint. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-21 15:44:35 -08:00

percpu: update alloc path to only scan if contig hints are broken Metadata is kept per block to keep track of where the contig hints are. Scanning can be avoided when the contig hints are not broken. In that case, left and right contigs have to be managed manually. This patch changes the allocation path hint updating to only scan when contig hints are broken. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:16 -04:00

percpu: use block scan_hint to only scan forward Blocks now remember the latest scan_hint. This can be used on the allocation path as when a contig_hint is broken, we can promote the scan_hint to the contig_hint and scan forward from there. This works because pcpu_block_refresh_hint() is only called on the allocation path while block free regions are updated manually in pcpu_block_update_hint_free(). Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-25 14:10:15 -08:00

percpu: update alloc path to only scan if contig hints are broken Metadata is kept per block to keep track of where the contig hints are. Scanning can be avoided when the contig hints are not broken. In that case, left and right contigs have to be managed manually. This patch changes the allocation path hint updating to only scan when contig hints are broken. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:16 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: update alloc path to only scan if contig hints are broken Metadata is kept per block to keep track of where the contig hints are. Scanning can be avoided when the contig hints are not broken. In that case, left and right contigs have to be managed manually. This patch changes the allocation path hint updating to only scan when contig hints are broken. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:16 -04:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: use block scan_hint to only scan forward Blocks now remember the latest scan_hint. This can be used on the allocation path as when a contig_hint is broken, we can promote the scan_hint to the contig_hint and scan forward from there. This works because pcpu_block_refresh_hint() is only called on the allocation path while block free regions are updated manually in pcpu_block_update_hint_free(). Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-25 14:10:15 -08:00

percpu: update alloc path to only scan if contig hints are broken Metadata is kept per block to keep track of where the contig hints are. Scanning can be avoided when the contig hints are not broken. In that case, left and right contigs have to be managed manually. This patch changes the allocation path hint updating to only scan when contig hints are broken. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:16 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

mm/percpu: add comment to state the empty populated pages accounting When allocating an area from a chunk, pcpu_block_update_hint_alloc() is called to update chunk metadata, including chunk's and global nr_empty_pop_pages. However, if the allocation is not atomic, some blocks may not be populated with pages yet, while we still subtract the number here. The number of pages will be added back with pcpu_chunk_populated() when populating pages. Adding code comment to make that more understandable. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2022-10-25 11:45:16 +08:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: use chunk scan_hint to skip some scanning Just like blocks, chunks now maintain a scan_hint. This can be used to skip some scanning by promoting the scan_hint to be the contig_hint. The chunk's scan_hint is primarily updated on the backside and relies on full scanning when a block becomes free or the free region spans across blocks. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:46:48 -08:00

percpu: update alloc path to only scan if contig hints are broken Metadata is kept per block to keep track of where the contig hints are. Scanning can be avoided when the contig hints are not broken. In that case, left and right contigs have to be managed manually. This patch changes the allocation path hint updating to only scan when contig hints are broken. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:16 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: introduce helper to determine if two regions overlap While block hints were always accurate, it's possible when spanning across blocks that we miss updating the chunk's contig_hint. Rather than rely on correctness of the boundaries of hints, do a full overlap comparison. A future patch introduces the scan_hint which makes the contig_hint slightly fuzzy as they can at times be smaller than the actual hint. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-21 15:44:35 -08:00

percpu: use chunk scan_hint to skip some scanning Just like blocks, chunks now maintain a scan_hint. This can be used to skip some scanning by promoting the scan_hint to be the contig_hint. The chunk's scan_hint is primarily updated on the backside and relies on full scanning when a block becomes free or the free region spans across blocks. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:46:48 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: add block level scan_hint Fragmentation can cause both blocks and chunks to have an early first_firee bit available, but only able to satisfy allocations much later on. This patch introduces a scan_hint to help mitigate some unnecessary scanning. The scan_hint remembers the largest area prior to the contig_hint. If the contig_hint == scan_hint, then scan_hint_start > contig_hint_start. This is necessary for scan_hint discovery when refreshing a block. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 13:41:45 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: use chunk scan_hint to skip some scanning Just like blocks, chunks now maintain a scan_hint. This can be used to skip some scanning by promoting the scan_hint to be the contig_hint. The chunk's scan_hint is primarily updated on the backside and relies on full scanning when a block becomes free or the free region spans across blocks. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:46:48 -08:00

percpu: update free path to take advantage of contig hints The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:17 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

2017-07-12 11:27:32 -07:00

mm/percpu: micro-optimize pcpu_is_populated() bitmap_next_clear_region() calls find_next_zero_bit() and find_next_bit() sequentially to find a range of clear bits. In case of pcpu_is_populated() there's a chance to return earlier if bitmap has all bits set. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org>

2021-08-14 14:17:10 -07:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

mm/percpu: micro-optimize pcpu_is_populated() bitmap_next_clear_region() calls find_next_zero_bit() and find_next_bit() sequentially to find a range of clear bits. In case of pcpu_is_populated() there's a chance to return earlier if bitmap has all bits set. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org>

2021-08-14 14:17:10 -07:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

mm/percpu: micro-optimize pcpu_is_populated() bitmap_next_clear_region() calls find_next_zero_bit() and find_next_bit() sequentially to find a range of clear bits. In case of pcpu_is_populated() there's a chance to return earlier if bitmap has all bits set. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org>

2021-08-14 14:17:10 -07:00

2017-07-12 11:27:32 -07:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

mm/percpu: micro-optimize pcpu_is_populated() bitmap_next_clear_region() calls find_next_zero_bit() and find_next_bit() sequentially to find a range of clear bits. In case of pcpu_is_populated() there's a chance to return earlier if bitmap has all bits set. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org>

2021-08-14 14:17:10 -07:00

2017-07-12 11:27:32 -07:00

percpu: move chunk area map extension out of area allocation Impact: code reorganization for later changes Separate out chunk area map extension into a separate function - pcpu_extend_area_map() - and call it directly from pcpu_alloc() such that pcpu_alloc_area() is guaranteed to have enough area map slots on invocation. With this change, pcpu_alloc_area() does only area allocation and the only failure mode is when the chunk doens't have enough room, so there's no need to distinguish it from memory allocation failures. Make it return -1 on such cases instead of hacky -ENOSPC. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

percpu: make pcpu_alloc_area() capable of allocating only from populated areas Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state. @pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

2017-07-12 11:27:32 -07:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

2017-07-12 11:27:32 -07:00

percpu: make pcpu_alloc_area() capable of allocating only from populated areas Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state. @pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

2017-07-12 11:27:32 -07:00

percpu: make pcpu_alloc_area() capable of allocating only from populated areas Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state. @pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

percpu: make pcpu_alloc_area() capable of allocating only from populated areas Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state. @pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

percpu: skip chunks if the alloc does not fit in the contig hint This patch adds chunk->contig_bits_start to keep track of the contig hint's offset and the check to skip the chunk if it does not fit. If the chunk's contig hint starting offset cannot satisfy an allocation, the allocator assumes there is enough memory pressure in this chunk to either use a different chunk or create a new one. This accepts a less tight packing for a smoother latency curve. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:14 -04:00

percpu: factor out pcpu_check_block_hint() Factor out the pcpu_check_block_hint() helper, which will be useful in the future. The new function checks if the allocation can likely fit within the contig hint. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:35 -07:00

percpu: skip chunks if the alloc does not fit in the contig hint This patch adds chunk->contig_bits_start to keep track of the contig hint's offset and the check to skip the chunk if it does not fit. If the chunk's contig hint starting offset cannot satisfy an allocation, the allocator assumes there is enough memory pressure in this chunk to either use a different chunk or create a new one. This accepts a less tight packing for a smoother latency curve. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:14 -04:00

percpu: factor out pcpu_check_block_hint() Factor out the pcpu_check_block_hint() helper, which will be useful in the future. The new function checks if the allocation can likely fit within the contig hint. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:35 -07:00

percpu: skip chunks if the alloc does not fit in the contig hint This patch adds chunk->contig_bits_start to keep track of the contig hint's offset and the check to skip the chunk if it does not fit. If the chunk's contig hint starting offset cannot satisfy an allocation, the allocator assumes there is enough memory pressure in this chunk to either use a different chunk or create a new one. This accepts a less tight packing for a smoother latency curve. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:14 -04:00

percpu: use chunk scan_hint to skip some scanning Just like blocks, chunks now maintain a scan_hint. This can be used to skip some scanning by promoting the scan_hint to be the contig_hint. The chunk's scan_hint is primarily updated on the backside and relies on full scanning when a block becomes free or the free region spans across blocks. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:46:48 -08:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

2017-07-12 11:27:32 -07:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

2017-07-12 11:27:32 -07:00

percpu: make pcpu_alloc_area() capable of allocating only from populated areas Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state. @pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

2017-07-12 11:27:32 -07:00

percpu: make pcpu_alloc_area() capable of allocating only from populated areas Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state. @pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

2017-07-12 11:27:32 -07:00

percpu: make pcpu_alloc_area() capable of allocating only from populated areas Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state. @pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

percpu: remember largest area skipped during allocation Percpu allocations attempt to do first fit by scanning forward from the first_free of a block. However, fragmentation from allocation requests can cause holes not seen by block hint update functions. To address this, create a local version of bitmap_find_next_zero_area_off() that remembers the largest area skipped over. The caveat is that it only sees regions skipped over due to not fitting, not regions skipped due to alignment. Prior to updating the scan_hint, a scan backwards is done to try and recover free bits skipped due to alignment. While this can cause scanning to miss earlier possible free areas, smaller allocations will eventually fill those holes due to first fit. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-22 09:03:16 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: move chunk area map extension out of area allocation Impact: code reorganization for later changes Separate out chunk area map extension into a separate function - pcpu_extend_area_map() - and call it directly from pcpu_alloc() such that pcpu_alloc_area() is guaranteed to have enough area map slots on invocation. With this change, pcpu_alloc_area() does only area allocation and the only failure mode is when the chunk doens't have enough room, so there's no need to distinguish it from memory allocation failures. Make it return -1 on such cases instead of hacky -ENOSPC. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:09 +09:00

2017-07-12 11:27:32 -07:00

percpu: update pcpu_find_block_fit to use an iterator The simple, and expensive, way to find a free area is to iterate over the entire bitmap until an area is found that fits the allocation size and alignment. This patch makes use of an iterate that find an area to check by using the block level contig hints. It will only return an area that can fit the size and alignment request. If the request can fit inside a block, it returns the first_free bit to start checking from to see if it can be fulfilled prior to the contig hint. The pcpu_alloc_area check has a bound of a block size added in case it is wrong. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:19 -04:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

2017-07-12 11:27:32 -07:00

percpu: remember largest area skipped during allocation Percpu allocations attempt to do first fit by scanning forward from the first_free of a block. However, fragmentation from allocation requests can cause holes not seen by block hint update functions. To address this, create a local version of bitmap_find_next_zero_area_off() that remembers the largest area skipped over. The caveat is that it only sees regions skipped over due to not fitting, not regions skipped due to alignment. Prior to updating the scan_hint, a scan backwards is done to try and recover free bits skipped due to alignment. While this can cause scanning to miss earlier possible free areas, smaller allocations will eventually fill those holes due to first fit. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-22 09:03:16 -08:00

2017-07-12 11:27:32 -07:00

percpu: make pcpu_alloc_area() capable of allocating only from populated areas Update pcpu_alloc_area() so that it can skip unpopulated areas if the new parameter @pop_only is true. This is implemented by a new function, pcpu_fit_in_area(), which determines the amount of head padding considering the alignment and populated state. @pop_only is currently always false but this will be used to implement atomic allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: do not search past bitmap when allocating an area pcpu_find_block_fit() guarantees that a fit is found within PCPU_BITMAP_BLOCK_BITS. Iteration is used to determine the first fit as it compares against the block's contig_hint. This can lead to incorrectly scanning past the end of the bitmap. The behavior was okay given the check after for bit_off >= end and the correctness of the hints from pcpu_find_block_fit(). This patch fixes this by bounding the end offset by the number of bits in a chunk. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-21 15:54:11 -08:00

percpu: remember largest area skipped during allocation Percpu allocations attempt to do first fit by scanning forward from the first_free of a block. However, fragmentation from allocation requests can cause holes not seen by block hint update functions. To address this, create a local version of bitmap_find_next_zero_area_off() that remembers the largest area skipped over. The caveat is that it only sees regions skipped over due to not fitting, not regions skipped due to alignment. Prior to updating the scan_hint, a scan backwards is done to try and recover free bits skipped due to alignment. While this can cause scanning to miss earlier possible free areas, smaller allocations will eventually fill those holes due to first fit. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-22 09:03:16 -08:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: remember largest area skipped during allocation Percpu allocations attempt to do first fit by scanning forward from the first_free of a block. However, fragmentation from allocation requests can cause holes not seen by block hint update functions. To address this, create a local version of bitmap_find_next_zero_area_off() that remembers the largest area skipped over. The caveat is that it only sees regions skipped over due to not fitting, not regions skipped due to alignment. Prior to updating the scan_hint, a scan backwards is done to try and recover free bits skipped due to alignment. While this can cause scanning to miss earlier possible free areas, smaller allocations will eventually fill those holes due to first fit. Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-22 09:03:16 -08:00

2017-07-12 11:27:32 -07:00

percpu: speed alloc_pcpu_area() up If we know that first N areas are all in use, we can obviously skip them when searching for a free one. And that kind of hint is very easy to maintain. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tejun Heo <tj@kernel.org>

2014-03-06 20:52:32 -05:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: add first_bit to keep track of the first free in the bitmap This patch adds first_bit to keep track of the first free bit in the bitmap. This hint helps prevent scanning of fully allocated blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:13 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: add first_bit to keep track of the first free in the bitmap This patch adds first_bit to keep track of the first free bit in the bitmap. This hint helps prevent scanning of fully allocated blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:13 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

2017-07-12 11:27:32 -07:00

percpu: return number of released bytes from pcpu_free_area() Patch series "mm: memcg accounting of percpu memory", v3. This patchset adds percpu memory accounting to memory cgroups. It's based on the rework of the slab controller and reuses concepts and features introduced for the per-object slab accounting. Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. Percpu allocations by their nature are scattered over multiple pages, so they can't be tracked on the per-page basis. So the per-object tracking introduced by the new slab controller is reused. The patchset implements charging of percpu allocations, adds memcg-level statistics, enables accounting for percpu allocations made by memory cgroup internals and provides some basic tests. To implement the accounting of percpu memory without a significant memory and performance overhead the following approach is used: all accounted allocations are placed into a separate percpu chunk (or chunks). These chunks are similar to default chunks, except that they do have an attached vector of pointers to obj_cgroup objects, which is big enough to save a pointer for each allocated object. On the allocation, if the allocation has to be accounted (__GFP_ACCOUNT is passed, the allocating process belongs to a non-root memory cgroup, etc), the memory cgroup is getting charged and if the maximum limit is not exceeded the allocation is performed using a memcg-aware chunk. Otherwise -ENOMEM is returned or the allocation is forced over the limit, depending on gfp (as any other kernel memory allocation). The memory cgroup information is saved in the obj_cgroup vector at the corresponding offset. On the release time the memcg information is restored from the vector and the cgroup is getting uncharged. Unaccounted allocations (at this point the absolute majority of all percpu allocations) are performed in the old way, so no additional overhead is expected. To avoid pinning dying memory cgroups by outstanding allocations, obj_cgroup API is used instead of directly saving memory cgroup pointers. obj_cgroup is basically a pointer to a memory cgroup with a standalone reference counter. The trick is that it can be atomically swapped to point at the parent cgroup, so that the original memory cgroup can be released prior to all objects, which has been charged to it. Because all charges and statistics are fully recursive, it's perfectly correct to uncharge the parent cgroup instead. This scheme is used in the slab memory accounting, and percpu memory can just follow the scheme. This patch (of 5): To implement accounting of percpu memory we need the information about the size of freed object. Return it from pcpu_free_area(). Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> cC: Michal Koutnýutny@suse.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-2-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:14 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: return number of released bytes from pcpu_free_area() Patch series "mm: memcg accounting of percpu memory", v3. This patchset adds percpu memory accounting to memory cgroups. It's based on the rework of the slab controller and reuses concepts and features introduced for the per-object slab accounting. Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. Percpu allocations by their nature are scattered over multiple pages, so they can't be tracked on the per-page basis. So the per-object tracking introduced by the new slab controller is reused. The patchset implements charging of percpu allocations, adds memcg-level statistics, enables accounting for percpu allocations made by memory cgroup internals and provides some basic tests. To implement the accounting of percpu memory without a significant memory and performance overhead the following approach is used: all accounted allocations are placed into a separate percpu chunk (or chunks). These chunks are similar to default chunks, except that they do have an attached vector of pointers to obj_cgroup objects, which is big enough to save a pointer for each allocated object. On the allocation, if the allocation has to be accounted (__GFP_ACCOUNT is passed, the allocating process belongs to a non-root memory cgroup, etc), the memory cgroup is getting charged and if the maximum limit is not exceeded the allocation is performed using a memcg-aware chunk. Otherwise -ENOMEM is returned or the allocation is forced over the limit, depending on gfp (as any other kernel memory allocation). The memory cgroup information is saved in the obj_cgroup vector at the corresponding offset. On the release time the memcg information is restored from the vector and the cgroup is getting uncharged. Unaccounted allocations (at this point the absolute majority of all percpu allocations) are performed in the old way, so no additional overhead is expected. To avoid pinning dying memory cgroups by outstanding allocations, obj_cgroup API is used instead of directly saving memory cgroup pointers. obj_cgroup is basically a pointer to a memory cgroup with a standalone reference counter. The trick is that it can be atomically swapped to point at the parent cgroup, so that the original memory cgroup can be released prior to all objects, which has been charged to it. Because all charges and statistics are fully recursive, it's perfectly correct to uncharge the parent cgroup instead. This scheme is used in the slab memory accounting, and percpu memory can just follow the scheme. This patch (of 5): To implement accounting of percpu memory we need the information about the size of freed object. Return it from pcpu_free_area(). Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> cC: Michal Koutnýutny@suse.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-2-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:14 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: return number of released bytes from pcpu_free_area() Patch series "mm: memcg accounting of percpu memory", v3. This patchset adds percpu memory accounting to memory cgroups. It's based on the rework of the slab controller and reuses concepts and features introduced for the per-object slab accounting. Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. Percpu allocations by their nature are scattered over multiple pages, so they can't be tracked on the per-page basis. So the per-object tracking introduced by the new slab controller is reused. The patchset implements charging of percpu allocations, adds memcg-level statistics, enables accounting for percpu allocations made by memory cgroup internals and provides some basic tests. To implement the accounting of percpu memory without a significant memory and performance overhead the following approach is used: all accounted allocations are placed into a separate percpu chunk (or chunks). These chunks are similar to default chunks, except that they do have an attached vector of pointers to obj_cgroup objects, which is big enough to save a pointer for each allocated object. On the allocation, if the allocation has to be accounted (__GFP_ACCOUNT is passed, the allocating process belongs to a non-root memory cgroup, etc), the memory cgroup is getting charged and if the maximum limit is not exceeded the allocation is performed using a memcg-aware chunk. Otherwise -ENOMEM is returned or the allocation is forced over the limit, depending on gfp (as any other kernel memory allocation). The memory cgroup information is saved in the obj_cgroup vector at the corresponding offset. On the release time the memcg information is restored from the vector and the cgroup is getting uncharged. Unaccounted allocations (at this point the absolute majority of all percpu allocations) are performed in the old way, so no additional overhead is expected. To avoid pinning dying memory cgroups by outstanding allocations, obj_cgroup API is used instead of directly saving memory cgroup pointers. obj_cgroup is basically a pointer to a memory cgroup with a standalone reference counter. The trick is that it can be atomically swapped to point at the parent cgroup, so that the original memory cgroup can be released prior to all objects, which has been charged to it. Because all charges and statistics are fully recursive, it's perfectly correct to uncharge the parent cgroup instead. This scheme is used in the slab memory accounting, and percpu memory can just follow the scheme. This patch (of 5): To implement accounting of percpu memory we need the information about the size of freed object. Return it from pcpu_free_area(). Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> cC: Michal Koutnýutny@suse.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-2-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:14 -07:00

percpu: store offsets instead of lengths in ->map[] Current code keeps +-length for each area in chunk->map[]. It has several unpleasant consequences: * even if we know that first 50 areas are all in use, allocation still needs to go through all those areas just to sum their sizes, just to get the offset of free one. * freeing needs to find the array entry refering to the area in question; again, the need to sum the sizes until we reach the offset we are interested in. Note that offsets are monotonous, so simple binary search would do here. New data representation: array of <offset,in-use flag> pairs. Each pair is represented by one int - we use offset|1 for <offset, in use> and offset for <offset, free> (we make sure that all offsets are even). In the end we put a sentry entry - <total size, in use>. The first entry is <0, flag>; it would be possible to store together the flag for Nth area and offset for N+1st, but that leads to much hairier code. In other words, where the old variant would have 4, -8, -4, 4, -12, 100 (4 bytes free, 8 in use, 4 in use, 4 free, 12 in use, 100 free) we store <0,0>, <4,1>, <12,1>, <16,0>, <20,1>, <32,0>, <132,1> i.e. 0, 5, 13, 16, 21, 32, 133 This commit switches to new data representation and takes care of a couple of low-hanging fruits in free_pcpu_area() - one is the switch to binary search, another is not doing two memmove() when one would do. Speeding the alloc side up (by keeping track of how many areas in the beginning are known to be all in use) also becomes possible - that'll be done in the next commit. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tejun Heo <tj@kernel.org>

2014-03-06 21:13:18 -05:00

percpu: add missing lockdep_assert_held to func pcpu_free_area Add a missing lockdep_assert_held for pcpu_lock to improve consistency and safety throughout mm/percpu.c. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:29 -04:00

percpu: expose statistics about percpu memory via debugfs There is limited visibility into the use of percpu memory leaving us unable to reason about correctness of parameters and overall use of percpu memory. These counters and statistics aim to help understand basic statistics about percpu memory such as number of allocations over the lifetime, allocation sizes, and fragmentation. New Config: PERCPU_STATS Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:31 -04:00

percpu: add missing lockdep_assert_held to func pcpu_free_area Add a missing lockdep_assert_held for pcpu_lock to improve consistency and safety throughout mm/percpu.c. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:29 -04:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

2017-07-12 11:27:32 -07:00

percpu: speed alloc_pcpu_area() up If we know that first N areas are all in use, we can obviously skip them when searching for a free one. And that kind of hint is very easy to maintain. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tejun Heo <tj@kernel.org>

2014-03-06 20:52:32 -05:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: return number of released bytes from pcpu_free_area() Patch series "mm: memcg accounting of percpu memory", v3. This patchset adds percpu memory accounting to memory cgroups. It's based on the rework of the slab controller and reuses concepts and features introduced for the per-object slab accounting. Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. Percpu allocations by their nature are scattered over multiple pages, so they can't be tracked on the per-page basis. So the per-object tracking introduced by the new slab controller is reused. The patchset implements charging of percpu allocations, adds memcg-level statistics, enables accounting for percpu allocations made by memory cgroup internals and provides some basic tests. To implement the accounting of percpu memory without a significant memory and performance overhead the following approach is used: all accounted allocations are placed into a separate percpu chunk (or chunks). These chunks are similar to default chunks, except that they do have an attached vector of pointers to obj_cgroup objects, which is big enough to save a pointer for each allocated object. On the allocation, if the allocation has to be accounted (__GFP_ACCOUNT is passed, the allocating process belongs to a non-root memory cgroup, etc), the memory cgroup is getting charged and if the maximum limit is not exceeded the allocation is performed using a memcg-aware chunk. Otherwise -ENOMEM is returned or the allocation is forced over the limit, depending on gfp (as any other kernel memory allocation). The memory cgroup information is saved in the obj_cgroup vector at the corresponding offset. On the release time the memcg information is restored from the vector and the cgroup is getting uncharged. Unaccounted allocations (at this point the absolute majority of all percpu allocations) are performed in the old way, so no additional overhead is expected. To avoid pinning dying memory cgroups by outstanding allocations, obj_cgroup API is used instead of directly saving memory cgroup pointers. obj_cgroup is basically a pointer to a memory cgroup with a standalone reference counter. The trick is that it can be atomically swapped to point at the parent cgroup, so that the original memory cgroup can be released prior to all objects, which has been charged to it. Because all charges and statistics are fully recursive, it's perfectly correct to uncharge the parent cgroup instead. This scheme is used in the slab memory accounting, and percpu memory can just follow the scheme. This patch (of 5): To implement accounting of percpu memory we need the information about the size of freed object. Return it from pcpu_free_area(). Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> cC: Michal Koutnýutny@suse.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-2-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:14 -07:00

2017-07-12 11:27:32 -07:00

percpu: return number of released bytes from pcpu_free_area() Patch series "mm: memcg accounting of percpu memory", v3. This patchset adds percpu memory accounting to memory cgroups. It's based on the rework of the slab controller and reuses concepts and features introduced for the per-object slab accounting. Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. Percpu allocations by their nature are scattered over multiple pages, so they can't be tracked on the per-page basis. So the per-object tracking introduced by the new slab controller is reused. The patchset implements charging of percpu allocations, adds memcg-level statistics, enables accounting for percpu allocations made by memory cgroup internals and provides some basic tests. To implement the accounting of percpu memory without a significant memory and performance overhead the following approach is used: all accounted allocations are placed into a separate percpu chunk (or chunks). These chunks are similar to default chunks, except that they do have an attached vector of pointers to obj_cgroup objects, which is big enough to save a pointer for each allocated object. On the allocation, if the allocation has to be accounted (__GFP_ACCOUNT is passed, the allocating process belongs to a non-root memory cgroup, etc), the memory cgroup is getting charged and if the maximum limit is not exceeded the allocation is performed using a memcg-aware chunk. Otherwise -ENOMEM is returned or the allocation is forced over the limit, depending on gfp (as any other kernel memory allocation). The memory cgroup information is saved in the obj_cgroup vector at the corresponding offset. On the release time the memcg information is restored from the vector and the cgroup is getting uncharged. Unaccounted allocations (at this point the absolute majority of all percpu allocations) are performed in the old way, so no additional overhead is expected. To avoid pinning dying memory cgroups by outstanding allocations, obj_cgroup API is used instead of directly saving memory cgroup pointers. obj_cgroup is basically a pointer to a memory cgroup with a standalone reference counter. The trick is that it can be atomically swapped to point at the parent cgroup, so that the original memory cgroup can be released prior to all objects, which has been charged to it. Because all charges and statistics are fully recursive, it's perfectly correct to uncharge the parent cgroup instead. This scheme is used in the slab memory accounting, and percpu memory can just follow the scheme. This patch (of 5): To implement accounting of percpu memory we need the information about the size of freed object. Return it from pcpu_free_area(). Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> cC: Michal Koutnýutny@suse.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-2-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:14 -07:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: add first_bit to keep track of the first free in the bitmap This patch adds first_bit to keep track of the first free bit in the bitmap. This hint helps prevent scanning of fully allocated blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:13 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: add first_bit to keep track of the first free in the bitmap This patch adds first_bit to keep track of the first free bit in the bitmap. This hint helps prevent scanning of fully allocated blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:13 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: return number of released bytes from pcpu_free_area() Patch series "mm: memcg accounting of percpu memory", v3. This patchset adds percpu memory accounting to memory cgroups. It's based on the rework of the slab controller and reuses concepts and features introduced for the per-object slab accounting. Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. Percpu allocations by their nature are scattered over multiple pages, so they can't be tracked on the per-page basis. So the per-object tracking introduced by the new slab controller is reused. The patchset implements charging of percpu allocations, adds memcg-level statistics, enables accounting for percpu allocations made by memory cgroup internals and provides some basic tests. To implement the accounting of percpu memory without a significant memory and performance overhead the following approach is used: all accounted allocations are placed into a separate percpu chunk (or chunks). These chunks are similar to default chunks, except that they do have an attached vector of pointers to obj_cgroup objects, which is big enough to save a pointer for each allocated object. On the allocation, if the allocation has to be accounted (__GFP_ACCOUNT is passed, the allocating process belongs to a non-root memory cgroup, etc), the memory cgroup is getting charged and if the maximum limit is not exceeded the allocation is performed using a memcg-aware chunk. Otherwise -ENOMEM is returned or the allocation is forced over the limit, depending on gfp (as any other kernel memory allocation). The memory cgroup information is saved in the obj_cgroup vector at the corresponding offset. On the release time the memcg information is restored from the vector and the cgroup is getting uncharged. Unaccounted allocations (at this point the absolute majority of all percpu allocations) are performed in the old way, so no additional overhead is expected. To avoid pinning dying memory cgroups by outstanding allocations, obj_cgroup API is used instead of directly saving memory cgroup pointers. obj_cgroup is basically a pointer to a memory cgroup with a standalone reference counter. The trick is that it can be atomically swapped to point at the parent cgroup, so that the original memory cgroup can be released prior to all objects, which has been charged to it. Because all charges and statistics are fully recursive, it's perfectly correct to uncharge the parent cgroup instead. This scheme is used in the slab memory accounting, and percpu memory can just follow the scheme. This patch (of 5): To implement accounting of percpu memory we need the information about the size of freed object. Return it from pcpu_free_area(). Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> cC: Michal Koutnýutny@suse.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-1-guro@fb.com Link: http://lkml.kernel.org/r/20200608230819.832349-2-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:14 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: make pcpu_block_md generic In reality, a chunk is just a block covering a larger number of bits. The hints themselves are one in the same. Rather than maintaining the hints separately, first introduce nr_bits to genericize pcpu_block_update() to correctly maintain block->right_free. The next patch will convert chunk hints to be managed as a pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 09:56:16 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: make pcpu_block_md generic In reality, a chunk is just a block covering a larger number of bits. The hints themselves are one in the same. Rather than maintaining the hints separately, first introduce nr_bits to genericize pcpu_block_update() to correctly maintain block->right_free. The next patch will convert chunk hints to be managed as a pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 09:56:16 -08:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

2017-07-12 11:27:32 -07:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

2017-07-12 11:27:32 -07:00

percpu: unify allocation of schunk and dchunk Create a common allocator for first chunk initialization, pcpu_alloc_first_chunk. Comments for this function will be added in a later patch once the bitmap allocator is added. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:02 -04:00

mm/percpu.c: remove the lcm code since block size is fixed at page size Since commit b239f7daf553 ("percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE"), the PCPU_BITMAP_BLOCK_SIZE has been set to page size fixedly. So the lcm code in pcpu_alloc_first_chunk() doesn't make sense any more, clean it up. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2022-10-24 16:14:33 +08:00

2017-07-12 11:27:32 -07:00

mm/percpu: add checks for the return value of memblock_alloc*() Add panic() calls if memblock_alloc() returns NULL. The panic() format duplicates the one used by memblock itself and in order to avoid explosion with long parameters list replace open coded allocation size calculations with a local variable. Link: http://lkml.kernel.org/r/1548057848-15136-17-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:15 -07:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

mm/percpu.c: remove the lcm code since block size is fixed at page size Since commit b239f7daf553 ("percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE"), the PCPU_BITMAP_BLOCK_SIZE has been set to page size fixedly. So the lcm code in pcpu_alloc_first_chunk() doesn't make sense any more, clean it up. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2022-10-24 16:14:33 +08:00

percpu: unify allocation of schunk and dchunk Create a common allocator for first chunk initialization, pcpu_alloc_first_chunk. Comments for this function will be added in a later patch once the bitmap allocator is added. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:02 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: convert flexible array initializers to use struct_size() Use the safer macro as sparked by the long discussion in [1]. [1] https://lore.kernel.org/lkml/20200917204514.GA2880159@google.com/ Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2020-10-30 20:40:21 +00:00

mm/percpu: add checks for the return value of memblock_alloc*() Add panic() calls if memblock_alloc() returns NULL. The panic() format duplicates the one used by memblock itself and in order to avoid explosion with long parameters list replace open coded allocation size calculations with a local variable. Link: http://lkml.kernel.org/r/1548057848-15136-17-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:15 -07:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: unify allocation of schunk and dchunk Create a common allocator for first chunk initialization, pcpu_alloc_first_chunk. Comments for this function will be added in a later patch once the bitmap allocator is added. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:02 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: unify allocation of schunk and dchunk Create a common allocator for first chunk initialization, pcpu_alloc_first_chunk. Comments for this function will be added in a later patch once the bitmap allocator is added. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:02 -04:00

percpu: end chunk area maps page aligned for the populated bitmap The area map allocator manages the first chunk area by hiding all but the region it is responsible for serving in the area map. To align this with the populated page bitmap, end_offset is introduced to keep track of the delta to end page aligned. The area map is appended with the page aligned end when necessary to be in line with how the bitmap allocator requires the ending to be aligned with the LCM of PAGE_SIZE and the size of each bitmap block. percpu_stats is updated to ignore this region when present. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:03 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: change the number of pages marked in the first_chunk pop bitmap The populated bitmap represents the state of the pages the chunk serves. Prior, the bitmap was marked completely used as the first chunk was allocated and immutable. This is misleading because the first chunk may not be completely filled. Additionally, with moving the base_addr up in the previous patch, the population check no longer corresponds to what was being checked. This patch modifies the population map to be only the number of pages the region serves and to make what it was checking correspond correctly again. The change is to remove any misunderstanding between the size of the populated bitmap and the actual size of it. The work function page iterators now use nr_pages for the check rather than pcpu_unit_pages because nr_populated is now chunk specific. Without this, the work function would try to populate the remainder of these chunks despite it not serving any more than nr_pages when nr_pages is set less than pcpu_unit_pages. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:07 -04:00

2017-07-12 11:27:32 -07:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

mm/percpu: add checks for the return value of memblock_alloc*() Add panic() calls if memblock_alloc() returns NULL. The panic() format duplicates the one used by memblock itself and in order to avoid explosion with long parameters list replace open coded allocation size calculations with a local variable. Link: http://lkml.kernel.org/r/1548057848-15136-17-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:15 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: unify allocation of schunk and dchunk Create a common allocator for first chunk initialization, pcpu_alloc_first_chunk. Comments for this function will be added in a later patch once the bitmap allocator is added. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:02 -04:00

percpu: change the number of pages marked in the first_chunk pop bitmap The populated bitmap represents the state of the pages the chunk serves. Prior, the bitmap was marked completely used as the first chunk was allocated and immutable. This is misleading because the first chunk may not be completely filled. Additionally, with moving the base_addr up in the previous patch, the population check no longer corresponds to what was being checked. This patch modifies the population map to be only the number of pages the region serves and to make what it was checking correspond correctly again. The change is to remove any misunderstanding between the size of the populated bitmap and the actual size of it. The work function page iterators now use nr_pages for the check rather than pcpu_unit_pages because nr_populated is now chunk specific. Without this, the work function would try to populate the remainder of these chunks despite it not serving any more than nr_pages when nr_pages is set less than pcpu_unit_pages. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:07 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: unify allocation of schunk and dchunk Create a common allocator for first chunk initialization, pcpu_alloc_first_chunk. Comments for this function will be added in a later patch once the bitmap allocator is added. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:02 -04:00

2017-07-12 11:27:32 -07:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

2017-07-12 11:27:32 -07:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: convert chunk hints to be based on pcpu_block_md As mentioned in the last patch, a chunk's hints are no different than a block just responsible for more bits. This converts chunk level hints to use a pcpu_block_md to maintain them. This lets us reuse the same hint helper functions as a block. The left_free and right_free are unused by the chunk's pcpu_block_md. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-26 10:00:08 -08:00

percpu: add first_bit to keep track of the first free in the bitmap This patch adds first_bit to keep track of the first free bit in the bitmap. This hint helps prevent scanning of fully allocated blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:13 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: end chunk area maps page aligned for the populated bitmap The area map allocator manages the first chunk area by hiding all but the region it is responsible for serving in the area map. To align this with the populated page bitmap, end_offset is introduced to keep track of the delta to end page aligned. The area map is appended with the page aligned end when necessary to be in line with how the bitmap allocator requires the ending to be aligned with the LCM of PAGE_SIZE and the size of each bitmap block. percpu_stats is updated to ignore this region when present. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:03 -04:00

2017-07-12 11:27:32 -07:00

percpu: end chunk area maps page aligned for the populated bitmap The area map allocator manages the first chunk area by hiding all but the region it is responsible for serving in the area map. To align this with the populated page bitmap, end_offset is introduced to keep track of the delta to end page aligned. The area map is appended with the page aligned end when necessary to be in line with how the bitmap allocator requires the ending to be aligned with the LCM of PAGE_SIZE and the size of each bitmap block. percpu_stats is updated to ignore this region when present. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:03 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

2017-07-12 11:27:32 -07:00

percpu: unify allocation of schunk and dchunk Create a common allocator for first chunk initialization, pcpu_alloc_first_chunk. Comments for this function will be added in a later patch once the bitmap allocator is added. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:02 -04:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

2017-07-12 11:27:32 -07:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

2017-07-12 11:27:32 -07:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

2017-07-12 11:27:32 -07:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

2017-07-12 11:27:32 -07:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

2017-07-12 11:27:32 -07:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

2017-07-12 11:27:32 -07:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

2017-07-12 11:27:32 -07:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

2017-07-12 11:27:32 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

2017-07-12 11:27:32 -07:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: stop leaking bitmap metadata blocks The commit ca460b3c9627 ("percpu: introduce bitmap metadata blocks") introduced bitmap metadata blocks. These metadata blocks are allocated whenever a new chunk is created, but they are never freed. Fix it. Fixes: ca460b3c9627 ("percpu: introduce bitmap metadata blocks") Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: stable@vger.kernel.org Signed-off-by: Dennis Zhou <dennis@kernel.org>

2018-10-07 11:31:51 +03:00

2017-07-12 11:27:32 -07:00

tree wide: use kvfree() than conditional kfree()/vfree() There are many locations that do if (memory_was_allocated_by_vmalloc) vfree(ptr); else kfree(ptr); but kvfree() can handle both kmalloc()ed memory and vmalloc()ed memory using is_vmalloc_addr(). Unless callers have special reasons, we can replace this branch with kvfree(). Please check and reply if you found problems. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Jan Kara <jack@suse.com> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Reviewed-by: Andreas Dilger <andreas.dilger@intel.com> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: David Rientjes <rientjes@google.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Oleg Drokin <oleg.drokin@intel.com> Cc: Boris Petkov <bp@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-01-22 15:11:02 -08:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

2017-07-12 11:27:32 -07:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

/proc/meminfo: add percpu populated pages count Currently, percpu memory only exposes allocation and utilization information via debugfs. This more or less is only really useful for understanding the fragmentation and allocation information at a per-chunk level with a few global counters. This is also gated behind a config. BPF and cgroup, for example, have seen an increase in use causing increased use of percpu memory. Let's make it easier for someone to identify how much memory is being used. This patch adds the "Percpu" stat to meminfo to more easily look up how much percpu memory is in use. This number includes the cost for all allocated backing pages and not just insight at the per a unit, per chunk level. Metadata is excluded. I think excluding metadata is fair because the backing memory scales with the numbere of cpus and can quickly outweigh the metadata. It also makes this calculation light. Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2018-08-21 21:53:58 -07:00

2017-07-12 11:27:32 -07:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

/proc/meminfo: add percpu populated pages count Currently, percpu memory only exposes allocation and utilization information via debugfs. This more or less is only really useful for understanding the fragmentation and allocation information at a per-chunk level with a few global counters. This is also gated behind a config. BPF and cgroup, for example, have seen an increase in use causing increased use of percpu memory. Let's make it easier for someone to identify how much memory is being used. This patch adds the "Percpu" stat to meminfo to more easily look up how much percpu memory is in use. This number includes the cost for all allocated backing pages and not just insight at the per a unit, per chunk level. Metadata is excluded. I think excluding metadata is fair because the backing memory scales with the numbere of cpus and can quickly outweigh the metadata. It also makes this calculation light. Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2018-08-21 21:53:58 -07:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: move vmalloc based chunk management into percpu-vm.c Separate out and move chunk management (creation/desctruction and [de]population) code into percpu-vm.c which is included by percpu.c and compiled together. The interface for chunk management is defined as follows. * pcpu_populate_chunk - populate the specified range of a chunk * pcpu_depopulate_chunk - depopulate the specified range of a chunk * pcpu_create_chunk - create a new chunk * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop * pcpu_addr_to_page - translate address to physical address * pcpu_verify_alloc_info - check alloc_info is acceptable during init Other than wrapping vmalloc_to_page() inside pcpu_addr_to_page() and dummy pcpu_verify_alloc_info() implementation, this patch only moves code around. This separation is to allow alternate chunk management implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

percpu: move vmalloc based chunk management into percpu-vm.c Separate out and move chunk management (creation/desctruction and [de]population) code into percpu-vm.c which is included by percpu.c and compiled together. The interface for chunk management is defined as follows. * pcpu_populate_chunk - populate the specified range of a chunk * pcpu_depopulate_chunk - depopulate the specified range of a chunk * pcpu_create_chunk - create a new chunk * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop * pcpu_addr_to_page - translate address to physical address * pcpu_verify_alloc_info - check alloc_info is acceptable during init Other than wrapping vmalloc_to_page() inside pcpu_addr_to_page() and dummy pcpu_verify_alloc_info() implementation, this patch only moves code around. This separation is to allow alternate chunk management implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: match chunk allocator declarations with definitions At some point the function declaration parameters got out of sync with the function definitions in percpu-vm.c and percpu-km.c. This patch makes them match again. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-15 10:08:14 -06:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

percpu: match chunk allocator declarations with definitions At some point the function declaration parameters got out of sync with the function definitions in percpu-vm.c and percpu-km.c. This patch makes them match again. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-15 10:08:14 -06:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: move vmalloc based chunk management into percpu-vm.c Separate out and move chunk management (creation/desctruction and [de]population) code into percpu-vm.c which is included by percpu.c and compiled together. The interface for chunk management is defined as follows. * pcpu_populate_chunk - populate the specified range of a chunk * pcpu_depopulate_chunk - depopulate the specified range of a chunk * pcpu_create_chunk - create a new chunk * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop * pcpu_addr_to_page - translate address to physical address * pcpu_verify_alloc_info - check alloc_info is acceptable during init Other than wrapping vmalloc_to_page() inside pcpu_addr_to_page() and dummy pcpu_verify_alloc_info() implementation, this patch only moves code around. This separation is to allow alternate chunk management implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implement kernel memory based chunk allocation Implement an alternate percpu chunk management based on kernel memeory for nommu SMP architectures. Instead of mapping into vmalloc area, chunks are allocated as a contiguous kernel memory using alloc_pages(). As such, percpu allocator on nommu will have the following restrictions. * It can't fill chunks on-demand page-by-page. It has to allocate each chunk fully upfront. * It can't support sparse chunk for NUMA configurations. SMP w/o mmu is crazy enough. Let's hope no one does NUMA w/o mmu. :-P * If chunk size isn't power-of-two multiple of PAGE_SIZE, the unaligned amount will be wasted on each chunk. So, archs which use this better align chunk size. For instructions on how to use this, read the comment on top of mm/percpu-km.c. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: move vmalloc based chunk management into percpu-vm.c Separate out and move chunk management (creation/desctruction and [de]population) code into percpu-vm.c which is included by percpu.c and compiled together. The interface for chunk management is defined as follows. * pcpu_populate_chunk - populate the specified range of a chunk * pcpu_depopulate_chunk - depopulate the specified range of a chunk * pcpu_create_chunk - create a new chunk * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop * pcpu_addr_to_page - translate address to physical address * pcpu_verify_alloc_info - check alloc_info is acceptable during init Other than wrapping vmalloc_to_page() inside pcpu_addr_to_page() and dummy pcpu_verify_alloc_info() implementation, this patch only moves code around. This separation is to allow alternate chunk management implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: implement kernel memory based chunk allocation Implement an alternate percpu chunk management based on kernel memeory for nommu SMP architectures. Instead of mapping into vmalloc area, chunks are allocated as a contiguous kernel memory using alloc_pages(). As such, percpu allocator on nommu will have the following restrictions. * It can't fill chunks on-demand page-by-page. It has to allocate each chunk fully upfront. * It can't support sparse chunk for NUMA configurations. SMP w/o mmu is crazy enough. Let's hope no one does NUMA w/o mmu. :-P * If chunk size isn't power-of-two multiple of PAGE_SIZE, the unaligned amount will be wasted on each chunk. So, archs which use this better align chunk size. For instructions on how to use this, read the comment on top of mm/percpu-km.c. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: misc preparations for nommu support Make the following misc preparations for percpu nommu support. * Remove refernces to vmalloc in common comments as nommu percpu won't use it. * Rename chunk->vms to chunk->data and make it void *. Its use is determined by chunk management implementation. * Relocate utility functions and add __maybe_unused to functions which might not be used by different chunk management implementations. This patch doesn't cause any functional change. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: misc preparations for nommu support Make the following misc preparations for percpu nommu support. * Remove refernces to vmalloc in common comments as nommu percpu won't use it. * Rename chunk->vms to chunk->data and make it void *. Its use is determined by chunk management implementation. * Relocate utility functions and add __maybe_unused to functions which might not be used by different chunk management implementations. This patch doesn't cause any functional change. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: combine percpu address checks The percpu address checks for the reserved and dynamic region chunks are now specific to each region. The address checking logic can be combined taking advantage of the global references to the dynamic and static region chunks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:06 -04:00

percpu: misc preparations for nommu support Make the following misc preparations for percpu nommu support. * Remove refernces to vmalloc in common comments as nommu percpu won't use it. * Rename chunk->vms to chunk->data and make it void *. Its use is determined by chunk management implementation. * Relocate utility functions and add __maybe_unused to functions which might not be used by different chunk management implementations. This patch doesn't cause any functional change. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: combine percpu address checks The percpu address checks for the reserved and dynamic region chunks are now specific to each region. The address checking logic can be combined taking advantage of the global references to the dynamic and static region chunks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:06 -04:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: misc preparations for nommu support Make the following misc preparations for percpu nommu support. * Remove refernces to vmalloc in common comments as nommu percpu won't use it. * Rename chunk->vms to chunk->data and make it void *. Its use is determined by chunk management implementation. * Relocate utility functions and add __maybe_unused to functions which might not be used by different chunk management implementations. This patch doesn't cause any functional change. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: move vmalloc based chunk management into percpu-vm.c Separate out and move chunk management (creation/desctruction and [de]population) code into percpu-vm.c which is included by percpu.c and compiled together. The interface for chunk management is defined as follows. * pcpu_populate_chunk - populate the specified range of a chunk * pcpu_depopulate_chunk - depopulate the specified range of a chunk * pcpu_create_chunk - create a new chunk * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop * pcpu_addr_to_page - translate address to physical address * pcpu_verify_alloc_info - check alloc_info is acceptable during init Other than wrapping vmalloc_to_page() inside pcpu_addr_to_page() and dummy pcpu_verify_alloc_info() implementation, this patch only moves code around. This separation is to allow alternate chunk management implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: misc preparations for nommu support Make the following misc preparations for percpu nommu support. * Remove refernces to vmalloc in common comments as nommu percpu won't use it. * Rename chunk->vms to chunk->data and make it void *. Its use is determined by chunk management implementation. * Relocate utility functions and add __maybe_unused to functions which might not be used by different chunk management implementations. This patch doesn't cause any functional change. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: memcontrol: rename memcg_kmem_enabled() Currently there are two kmem-related helper functions with a confusing semantics: memcg_kmem_enabled() and mem_cgroup_kmem_disabled(). The problem is that an obvious expectation memcg_kmem_enabled() == !mem_cgroup_kmem_disabled(), can be false. mem_cgroup_kmem_disabled() is similar to mem_cgroup_disabled(): it returns true only if CONFIG_MEMCG_KMEM is not set or the kmem accounting is disabled using a boot time kernel option "cgroup.memory=nokmem". It never changes the value dynamically. memcg_kmem_enabled() is different: it always returns false until the first non-root memory cgroup will get online (assuming the kernel memory accounting is enabled). It's goal is to improve the performance on systems without the cgroupfs mounted/memory controller enabled or on the systems with only the root memory cgroup. To make things more obvious and avoid potential bugs, let's rename memcg_kmem_enabled() to memcg_kmem_online(). Link: https://lkml.kernel.org/r/20230213192922.1146370-1-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Dennis Zhou <dennis@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2023-02-13 11:29:22 -08:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: scoped objcg protection Similar to slab and kmem, switch to a scope-based protection of the objcg pointer to avoid. Link: https://lkml.kernel.org/r/20231019225346.1822282-6-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Acked-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2023-10-19 15:53:45 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: scoped objcg protection Similar to slab and kmem, switch to a scope-based protection of the objcg pointer to avoid. Link: https://lkml.kernel.org/r/20231019225346.1822282-6-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Acked-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2023-10-19 15:53:45 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: scoped objcg protection Similar to slab and kmem, switch to a scope-based protection of the objcg pointer to avoid. Link: https://lkml.kernel.org/r/20231019225346.1822282-6-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Acked-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2023-10-19 15:53:45 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: memcg/percpu: per-memcg percpu memory statistics Percpu memory can represent a noticeable chunk of the total memory consumption, especially on big machines with many CPUs. Let's track percpu memory usage for each memcg and display it in memory.stat. A percpu allocation is usually scattered over multiple pages (and nodes), and can be significantly smaller than a page. So let's add a byte-sized counter on the memcg level: MEMCG_PERCPU_B. Byte-sized vmstat infra created for slabs can be perfectly reused for percpu case. [guro@fb.com: v3] Link: http://lkml.kernel.org/r/20200623184515.4132564-4-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200608230819.832349-4-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:21 -07:00

mm: memcg/percpu: account extra objcg space to memory cgroups Similar to slab memory allocator, for each accounted percpu object there is an extra space which is used to store obj_cgroup membership. Charge it too. [akpm@linux-foundation.org: fix layout] Link: https://lkml.kernel.org/r/20211126040606.97836-1-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-14 14:09:12 -08:00

mm: memcg/percpu: per-memcg percpu memory statistics Percpu memory can represent a noticeable chunk of the total memory consumption, especially on big machines with many CPUs. Let's track percpu memory usage for each memcg and display it in memory.stat. A percpu allocation is usually scattered over multiple pages (and nodes), and can be significantly smaller than a page. So let's add a byte-sized counter on the memcg level: MEMCG_PERCPU_B. Byte-sized vmstat infra created for slabs can be perfectly reused for percpu case. [guro@fb.com: v3] Link: http://lkml.kernel.org/r/20200623184515.4132564-4-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200608230819.832349-4-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:21 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: memcg/percpu: account extra objcg space to memory cgroups Similar to slab memory allocator, for each accounted percpu object there is an extra space which is used to store obj_cgroup membership. Charge it too. [akpm@linux-foundation.org: fix layout] Link: https://lkml.kernel.org/r/20211126040606.97836-1-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-14 14:09:12 -08:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: memcg/percpu: account extra objcg space to memory cgroups Similar to slab memory allocator, for each accounted percpu object there is an extra space which is used to store obj_cgroup membership. Charge it too. [akpm@linux-foundation.org: fix layout] Link: https://lkml.kernel.org/r/20211126040606.97836-1-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-14 14:09:12 -08:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: memcg/percpu: per-memcg percpu memory statistics Percpu memory can represent a noticeable chunk of the total memory consumption, especially on big machines with many CPUs. Let's track percpu memory usage for each memcg and display it in memory.stat. A percpu allocation is usually scattered over multiple pages (and nodes), and can be significantly smaller than a page. So let's add a byte-sized counter on the memcg level: MEMCG_PERCPU_B. Byte-sized vmstat infra created for slabs can be perfectly reused for percpu case. [guro@fb.com: v3] Link: http://lkml.kernel.org/r/20200623184515.4132564-4-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200608230819.832349-4-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:21 -07:00

mm: memcg/percpu: account extra objcg space to memory cgroups Similar to slab memory allocator, for each accounted percpu object there is an extra space which is used to store obj_cgroup membership. Charge it too. [akpm@linux-foundation.org: fix layout] Link: https://lkml.kernel.org/r/20211126040606.97836-1-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-14 14:09:12 -08:00

mm: memcg/percpu: per-memcg percpu memory statistics Percpu memory can represent a noticeable chunk of the total memory consumption, especially on big machines with many CPUs. Let's track percpu memory usage for each memcg and display it in memory.stat. A percpu allocation is usually scattered over multiple pages (and nodes), and can be significantly smaller than a page. So let's add a byte-sized counter on the memcg level: MEMCG_PERCPU_B. Byte-sized vmstat infra created for slabs can be perfectly reused for percpu case. [guro@fb.com: v3] Link: http://lkml.kernel.org/r/20200623184515.4132564-4-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200608230819.832349-4-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:21 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: clean up size usage Andrew was concerned about the unit of variables named or have suffix size. Every usage in percpu allocator is in bytes but make it super clear by adding comments. While at it, make pcpu_depopulate_chunk() take int @off and @size like everyone else. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-21 16:56:23 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

mm, percpu: add support for __GFP_NOWARN flag Add an option for pcpu_alloc() to support __GFP_NOWARN flag. Currently, we always throw a warning when size or alignment is unsupported (and also dump stack on failed allocation requests). The warning itself is harmless since we return NULL anyway for any failed request, which callers are required to handle anyway. However, it becomes harmful when panic_on_warn is set. The rationale for the WARN() in pcpu_alloc() is that it can be tracked when larger than supported allocation requests are made such that allocations limits can be tweaked if warranted. This makes sense for in-kernel users, however, there are users of pcpu allocator where allocation size is derived from user space requests, e.g. when creating BPF maps. In these cases, the requests should fail gracefully without throwing a splat. The current work-around was to check allocation size against the upper limit of PCPU_MIN_UNIT_SIZE from call-sites for bailing out prior to a call to pcpu_alloc() in order to avoid throwing the WARN(). This is bad in multiple ways since PCPU_MIN_UNIT_SIZE is an implementation detail, and having the checks on call-sites only complicates the code for no good reason. Thus, lets fix it generically by supporting the __GFP_NOWARN flag that users can then use with calling the __alloc_percpu_gfp() helper instead. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>

2017-10-17 16:55:52 +02:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: make pcpu_alloc() aware of current gfp context Since 5.7-rc1, on btrfs we have a percpu counter initialization for which we always pass a GFP_KERNEL gfp_t argument (this happens since commit 2992df73268f78 ("btrfs: Implement DREW lock")). That is safe in some contextes but not on others where allowing fs reclaim could lead to a deadlock because we are either holding some btrfs lock needed for a transaction commit or holding a btrfs transaction handle open. Because of that we surround the call to the function that initializes the percpu counter with a NOFS context using memalloc_nofs_save() (this is done at btrfs_init_fs_root()). However it turns out that this is not enough to prevent a possible deadlock because percpu_alloc() determines if it is in an atomic context by looking exclusively at the gfp flags passed to it (GFP_KERNEL in this case) and it is not aware that a NOFS context is set. Because percpu_alloc() thinks it is in a non atomic context it locks the pcpu_alloc_mutex. This can result in a btrfs deadlock when pcpu_balance_workfn() is running, has acquired that mutex and is waiting for reclaim, while the btrfs task that called percpu_counter_init() (and therefore percpu_alloc()) is holding either the btrfs commit_root semaphore or a transaction handle (done fs/btrfs/backref.c: iterate_extent_inodes()), which prevents reclaim from finishing as an attempt to commit the current btrfs transaction will deadlock. Lockdep reports this issue with the following trace: ====================================================== WARNING: possible circular locking dependency detected 5.6.0-rc7-btrfs-next-77 #1 Not tainted ------------------------------------------------------ kswapd0/91 is trying to acquire lock: ffff8938a3b3fdc8 (&delayed_node->mutex){+.+.}, at: __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] but task is already holding lock: ffffffffb4f0dbc0 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (fs_reclaim){+.+.}: fs_reclaim_acquire.part.0+0x25/0x30 __kmalloc+0x5f/0x3a0 pcpu_create_chunk+0x19/0x230 pcpu_balance_workfn+0x56a/0x680 process_one_work+0x235/0x5f0 worker_thread+0x50/0x3b0 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 -> #3 (pcpu_alloc_mutex){+.+.}: __mutex_lock+0xa9/0xaf0 pcpu_alloc+0x480/0x7c0 __percpu_counter_init+0x50/0xd0 btrfs_drew_lock_init+0x22/0x70 [btrfs] btrfs_get_fs_root+0x29c/0x5c0 [btrfs] resolve_indirect_refs+0x120/0xa30 [btrfs] find_parent_nodes+0x50b/0xf30 [btrfs] btrfs_find_all_leafs+0x60/0xb0 [btrfs] iterate_extent_inodes+0x139/0x2f0 [btrfs] iterate_inodes_from_logical+0xa1/0xe0 [btrfs] btrfs_ioctl_logical_to_ino+0xb4/0x190 [btrfs] btrfs_ioctl+0x165a/0x3130 [btrfs] ksys_ioctl+0x87/0xc0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x5c/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&fs_info->commit_root_sem){++++}: down_write+0x38/0x70 btrfs_cache_block_group+0x2ec/0x500 [btrfs] find_free_extent+0xc6a/0x1600 [btrfs] btrfs_reserve_extent+0x9b/0x180 [btrfs] btrfs_alloc_tree_block+0xc1/0x350 [btrfs] alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs] __btrfs_cow_block+0x122/0x5a0 [btrfs] btrfs_cow_block+0x106/0x240 [btrfs] commit_cowonly_roots+0x55/0x310 [btrfs] btrfs_commit_transaction+0x509/0xb20 [btrfs] sync_filesystem+0x74/0x90 generic_shutdown_super+0x22/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 [btrfs] deactivate_locked_super+0x31/0x70 cleanup_mnt+0x100/0x160 task_work_run+0x93/0xc0 exit_to_usermode_loop+0xf9/0x100 do_syscall_64+0x20d/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&space_info->groups_sem){++++}: down_read+0x3c/0x140 find_free_extent+0xef6/0x1600 [btrfs] btrfs_reserve_extent+0x9b/0x180 [btrfs] btrfs_alloc_tree_block+0xc1/0x350 [btrfs] alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs] __btrfs_cow_block+0x122/0x5a0 [btrfs] btrfs_cow_block+0x106/0x240 [btrfs] btrfs_search_slot+0x50c/0xd60 [btrfs] btrfs_lookup_inode+0x3a/0xc0 [btrfs] __btrfs_update_delayed_inode+0x90/0x280 [btrfs] __btrfs_commit_inode_delayed_items+0x81f/0x870 [btrfs] __btrfs_run_delayed_items+0x8e/0x180 [btrfs] btrfs_commit_transaction+0x31b/0xb20 [btrfs] iterate_supers+0x87/0xf0 ksys_sync+0x60/0xb0 __ia32_sys_sync+0xa/0x10 do_syscall_64+0x5c/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&delayed_node->mutex){+.+.}: __lock_acquire+0xef0/0x1c80 lock_acquire+0xa2/0x1d0 __mutex_lock+0xa9/0xaf0 __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] btrfs_evict_inode+0x40d/0x560 [btrfs] evict+0xd9/0x1c0 dispose_list+0x48/0x70 prune_icache_sb+0x54/0x80 super_cache_scan+0x124/0x1a0 do_shrink_slab+0x176/0x440 shrink_slab+0x23a/0x2c0 shrink_node+0x188/0x6e0 balance_pgdat+0x31d/0x7f0 kswapd+0x238/0x550 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 other info that might help us debug this: Chain exists of: &delayed_node->mutex --> pcpu_alloc_mutex --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(pcpu_alloc_mutex); lock(fs_reclaim); lock(&delayed_node->mutex); *** DEADLOCK *** 3 locks held by kswapd0/91: #0: (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 #1: (shrinker_rwsem){++++}, at: shrink_slab+0x12f/0x2c0 #2: (&type->s_umount_key#43){++++}, at: trylock_super+0x16/0x50 stack backtrace: CPU: 1 PID: 91 Comm: kswapd0 Not tainted 5.6.0-rc7-btrfs-next-77 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0x8f/0xd0 check_noncircular+0x170/0x190 __lock_acquire+0xef0/0x1c80 lock_acquire+0xa2/0x1d0 __mutex_lock+0xa9/0xaf0 __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] btrfs_evict_inode+0x40d/0x560 [btrfs] evict+0xd9/0x1c0 dispose_list+0x48/0x70 prune_icache_sb+0x54/0x80 super_cache_scan+0x124/0x1a0 do_shrink_slab+0x176/0x440 shrink_slab+0x23a/0x2c0 shrink_node+0x188/0x6e0 balance_pgdat+0x31d/0x7f0 kswapd+0x238/0x550 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 This could be fixed by making btrfs pass GFP_NOFS instead of GFP_KERNEL to percpu_counter_init() in contextes where it is not reclaim safe, however that type of approach is discouraged since memalloc_[nofs|noio]_save() were introduced. Therefore this change makes pcpu_alloc() look up into an existing nofs/noio context before deciding whether it is in an atomic context or not. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Link: http://lkml.kernel.org/r/20200430164356.15543-1-fdmanana@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-05-07 18:36:10 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: make allocation failures more verbose Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-29 09:17:58 +09:00

percpu: relegate chunks unusable when failing small allocations In certain cases, requestors of percpu memory may want specific alignments. However, it is possible to end up in situations where the contig_hint matches, but the alignment does not. This causes excess scanning of chunks that will fail. To prevent this, if a small allocation fails (< 32B), the chunk is moved to the empty list. Once an allocation is freed from that chunk, it is placed back into rotation. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 09:03:50 -08:00

percpu: make allocation failures more verbose Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-29 09:17:58 +09:00

2017-07-12 11:27:32 -07:00

percpu: allow pcpu_alloc() to be called with IRQs off pcpu_alloc() and pcpu_extend_area_map() perform a series of spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe with respect to being called from contexts which have IRQs off. This patch converts the code to perform save/restore of flags instead, making pcpu_alloc() (or __alloc_percpu() respectively) to be called from early kernel startup stage, where IRQs are off. This is needed for proper initialization of per-cpu rq_weight data from sched_init(). tj: added comment explaining why irqsave/restore is used in alloc path. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Tejun Heo <tj@kernel.org>

2009-10-29 00:25:59 +09:00

kmemleak: Handle percpu memory allocation This patch adds kmemleak callbacks from the percpu allocator, reducing a number of false positives caused by kmemleak not scanning such memory blocks. The percpu chunks are never reported as leaks because of current kmemleak limitations with the __percpu pointer not pointing directly to the actual chunks. Reported-by: Huajun Li <huajun.li.lee@gmail.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2011-09-26 17:12:53 +01:00

2017-07-12 11:27:32 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: make pcpu_alloc() aware of current gfp context Since 5.7-rc1, on btrfs we have a percpu counter initialization for which we always pass a GFP_KERNEL gfp_t argument (this happens since commit 2992df73268f78 ("btrfs: Implement DREW lock")). That is safe in some contextes but not on others where allowing fs reclaim could lead to a deadlock because we are either holding some btrfs lock needed for a transaction commit or holding a btrfs transaction handle open. Because of that we surround the call to the function that initializes the percpu counter with a NOFS context using memalloc_nofs_save() (this is done at btrfs_init_fs_root()). However it turns out that this is not enough to prevent a possible deadlock because percpu_alloc() determines if it is in an atomic context by looking exclusively at the gfp flags passed to it (GFP_KERNEL in this case) and it is not aware that a NOFS context is set. Because percpu_alloc() thinks it is in a non atomic context it locks the pcpu_alloc_mutex. This can result in a btrfs deadlock when pcpu_balance_workfn() is running, has acquired that mutex and is waiting for reclaim, while the btrfs task that called percpu_counter_init() (and therefore percpu_alloc()) is holding either the btrfs commit_root semaphore or a transaction handle (done fs/btrfs/backref.c: iterate_extent_inodes()), which prevents reclaim from finishing as an attempt to commit the current btrfs transaction will deadlock. Lockdep reports this issue with the following trace: ====================================================== WARNING: possible circular locking dependency detected 5.6.0-rc7-btrfs-next-77 #1 Not tainted ------------------------------------------------------ kswapd0/91 is trying to acquire lock: ffff8938a3b3fdc8 (&delayed_node->mutex){+.+.}, at: __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] but task is already holding lock: ffffffffb4f0dbc0 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (fs_reclaim){+.+.}: fs_reclaim_acquire.part.0+0x25/0x30 __kmalloc+0x5f/0x3a0 pcpu_create_chunk+0x19/0x230 pcpu_balance_workfn+0x56a/0x680 process_one_work+0x235/0x5f0 worker_thread+0x50/0x3b0 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 -> #3 (pcpu_alloc_mutex){+.+.}: __mutex_lock+0xa9/0xaf0 pcpu_alloc+0x480/0x7c0 __percpu_counter_init+0x50/0xd0 btrfs_drew_lock_init+0x22/0x70 [btrfs] btrfs_get_fs_root+0x29c/0x5c0 [btrfs] resolve_indirect_refs+0x120/0xa30 [btrfs] find_parent_nodes+0x50b/0xf30 [btrfs] btrfs_find_all_leafs+0x60/0xb0 [btrfs] iterate_extent_inodes+0x139/0x2f0 [btrfs] iterate_inodes_from_logical+0xa1/0xe0 [btrfs] btrfs_ioctl_logical_to_ino+0xb4/0x190 [btrfs] btrfs_ioctl+0x165a/0x3130 [btrfs] ksys_ioctl+0x87/0xc0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x5c/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&fs_info->commit_root_sem){++++}: down_write+0x38/0x70 btrfs_cache_block_group+0x2ec/0x500 [btrfs] find_free_extent+0xc6a/0x1600 [btrfs] btrfs_reserve_extent+0x9b/0x180 [btrfs] btrfs_alloc_tree_block+0xc1/0x350 [btrfs] alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs] __btrfs_cow_block+0x122/0x5a0 [btrfs] btrfs_cow_block+0x106/0x240 [btrfs] commit_cowonly_roots+0x55/0x310 [btrfs] btrfs_commit_transaction+0x509/0xb20 [btrfs] sync_filesystem+0x74/0x90 generic_shutdown_super+0x22/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 [btrfs] deactivate_locked_super+0x31/0x70 cleanup_mnt+0x100/0x160 task_work_run+0x93/0xc0 exit_to_usermode_loop+0xf9/0x100 do_syscall_64+0x20d/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&space_info->groups_sem){++++}: down_read+0x3c/0x140 find_free_extent+0xef6/0x1600 [btrfs] btrfs_reserve_extent+0x9b/0x180 [btrfs] btrfs_alloc_tree_block+0xc1/0x350 [btrfs] alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs] __btrfs_cow_block+0x122/0x5a0 [btrfs] btrfs_cow_block+0x106/0x240 [btrfs] btrfs_search_slot+0x50c/0xd60 [btrfs] btrfs_lookup_inode+0x3a/0xc0 [btrfs] __btrfs_update_delayed_inode+0x90/0x280 [btrfs] __btrfs_commit_inode_delayed_items+0x81f/0x870 [btrfs] __btrfs_run_delayed_items+0x8e/0x180 [btrfs] btrfs_commit_transaction+0x31b/0xb20 [btrfs] iterate_supers+0x87/0xf0 ksys_sync+0x60/0xb0 __ia32_sys_sync+0xa/0x10 do_syscall_64+0x5c/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&delayed_node->mutex){+.+.}: __lock_acquire+0xef0/0x1c80 lock_acquire+0xa2/0x1d0 __mutex_lock+0xa9/0xaf0 __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] btrfs_evict_inode+0x40d/0x560 [btrfs] evict+0xd9/0x1c0 dispose_list+0x48/0x70 prune_icache_sb+0x54/0x80 super_cache_scan+0x124/0x1a0 do_shrink_slab+0x176/0x440 shrink_slab+0x23a/0x2c0 shrink_node+0x188/0x6e0 balance_pgdat+0x31d/0x7f0 kswapd+0x238/0x550 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 other info that might help us debug this: Chain exists of: &delayed_node->mutex --> pcpu_alloc_mutex --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(pcpu_alloc_mutex); lock(fs_reclaim); lock(&delayed_node->mutex); *** DEADLOCK *** 3 locks held by kswapd0/91: #0: (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 #1: (shrinker_rwsem){++++}, at: shrink_slab+0x12f/0x2c0 #2: (&type->s_umount_key#43){++++}, at: trylock_super+0x16/0x50 stack backtrace: CPU: 1 PID: 91 Comm: kswapd0 Not tainted 5.6.0-rc7-btrfs-next-77 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0x8f/0xd0 check_noncircular+0x170/0x190 __lock_acquire+0xef0/0x1c80 lock_acquire+0xa2/0x1d0 __mutex_lock+0xa9/0xaf0 __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs] btrfs_evict_inode+0x40d/0x560 [btrfs] evict+0xd9/0x1c0 dispose_list+0x48/0x70 prune_icache_sb+0x54/0x80 super_cache_scan+0x124/0x1a0 do_shrink_slab+0x176/0x440 shrink_slab+0x23a/0x2c0 shrink_node+0x188/0x6e0 balance_pgdat+0x31d/0x7f0 kswapd+0x238/0x550 kthread+0x120/0x140 ret_from_fork+0x3a/0x50 This could be fixed by making btrfs pass GFP_NOFS instead of GFP_KERNEL to percpu_counter_init() in contextes where it is not reclaim safe, however that type of approach is discouraged since memalloc_[nofs|noio]_save() were introduced. Therefore this change makes pcpu_alloc() look up into an existing nofs/noio context before deciding whether it is in an atomic context or not. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Link: http://lkml.kernel.org/r/20200430164356.15543-1-fdmanana@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-05-07 18:36:10 -07:00

percpu: store offsets instead of lengths in ->map[] Current code keeps +-length for each area in chunk->map[]. It has several unpleasant consequences: * even if we know that first 50 areas are all in use, allocation still needs to go through all those areas just to sum their sizes, just to get the offset of free one. * freeing needs to find the array entry refering to the area in question; again, the need to sum the sizes until we reach the offset we are interested in. Note that offsets are monotonous, so simple binary search would do here. New data representation: array of <offset,in-use flag> pairs. Each pair is represented by one int - we use offset|1 for <offset, in use> and offset for <offset, free> (we make sure that all offsets are even). In the end we put a sentry entry - <total size, in use>. The first entry is <0, flag>; it would be possible to store together the flag for Nth area and offset for N+1st, but that leads to much hairier code. In other words, where the old variant would have 4, -8, -4, 4, -12, 100 (4 bytes free, 8 in use, 4 in use, 4 free, 12 in use, 100 free) we store <0,0>, <4,1>, <12,1>, <16,0>, <20,1>, <32,0>, <132,1> i.e. 0, 5, 13, 16, 21, 32, 133 This commit switches to new data representation and takes care of a couple of low-hanging fruits in free_pcpu_area() - one is the switch to binary search, another is not doing two memmove() when one would do. Speeding the alloc side up (by keeping track of how many areas in the beginning are known to be all in use) also becomes possible - that'll be done in the next commit. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tejun Heo <tj@kernel.org>

2014-03-06 21:13:18 -05:00

2017-07-12 11:27:32 -07:00

percpu: store offsets instead of lengths in ->map[] Current code keeps +-length for each area in chunk->map[]. It has several unpleasant consequences: * even if we know that first 50 areas are all in use, allocation still needs to go through all those areas just to sum their sizes, just to get the offset of free one. * freeing needs to find the array entry refering to the area in question; again, the need to sum the sizes until we reach the offset we are interested in. Note that offsets are monotonous, so simple binary search would do here. New data representation: array of <offset,in-use flag> pairs. Each pair is represented by one int - we use offset|1 for <offset, in use> and offset for <offset, free> (we make sure that all offsets are even). In the end we put a sentry entry - <total size, in use>. The first entry is <0, flag>; it would be possible to store together the flag for Nth area and offset for N+1st, but that leads to much hairier code. In other words, where the old variant would have 4, -8, -4, 4, -12, 100 (4 bytes free, 8 in use, 4 in use, 4 free, 12 in use, 100 free) we store <0,0>, <4,1>, <12,1>, <16,0>, <20,1>, <32,0>, <132,1> i.e. 0, 5, 13, 16, 21, 32, 133 This commit switches to new data representation and takes care of a couple of low-hanging fruits in free_pcpu_area() - one is the switch to binary search, another is not doing two memmove() when one would do. Speeding the alloc side up (by keeping track of how many areas in the beginning are known to be all in use) also becomes possible - that'll be done in the next commit. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tejun Heo <tj@kernel.org>

2014-03-06 21:13:18 -05:00

percpu: increase minimum percpu allocation size and align first regions This patch increases the minimum allocation size of percpu memory to 4-bytes. This change will help minimize the metadata overhead associated with the bitmap allocator. The assumption is that most allocations will be of objects or structs greater than 2 bytes with integers or longs being used rather than shorts. The first chunk regions are now aligned with the minimum allocation size. The reserved region is expected to be set as a multiple of the minimum allocation size. The static region is aligned up and the delta is removed from the dynamic size. This works because the dynamic size is increased to be page aligned. If the static size is not minimum allocation size aligned, then there must be a gap that is added to the dynamic size. The dynamic size will never be smaller than the set value. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:09 -04:00

percpu: store offsets instead of lengths in ->map[] Current code keeps +-length for each area in chunk->map[]. It has several unpleasant consequences: * even if we know that first 50 areas are all in use, allocation still needs to go through all those areas just to sum their sizes, just to get the offset of free one. * freeing needs to find the array entry refering to the area in question; again, the need to sum the sizes until we reach the offset we are interested in. Note that offsets are monotonous, so simple binary search would do here. New data representation: array of <offset,in-use flag> pairs. Each pair is represented by one int - we use offset|1 for <offset, in use> and offset for <offset, free> (we make sure that all offsets are even). In the end we put a sentry entry - <total size, in use>. The first entry is <0, flag>; it would be possible to store together the flag for Nth area and offset for N+1st, but that leads to much hairier code. In other words, where the old variant would have 4, -8, -4, 4, -12, 100 (4 bytes free, 8 in use, 4 in use, 4 free, 12 in use, 100 free) we store <0,0>, <4,1>, <12,1>, <16,0>, <20,1>, <32,0>, <132,1> i.e. 0, 5, 13, 16, 21, 32, 133 This commit switches to new data representation and takes care of a couple of low-hanging fruits in free_pcpu_area() - one is the switch to binary search, another is not doing two memmove() when one would do. Speeding the alloc side up (by keeping track of how many areas in the beginning are known to be all in use) also becomes possible - that'll be done in the next commit. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tejun Heo <tj@kernel.org>

2014-03-06 21:13:18 -05:00

percpu: increase minimum percpu allocation size and align first regions This patch increases the minimum allocation size of percpu memory to 4-bytes. This change will help minimize the metadata overhead associated with the bitmap allocator. The assumption is that most allocations will be of objects or structs greater than 2 bytes with integers or longs being used rather than shorts. The first chunk regions are now aligned with the minimum allocation size. The reserved region is expected to be set as a multiple of the minimum allocation size. The static region is aligned up and the delta is removed from the dynamic size. This works because the dynamic size is increased to be page aligned. If the static size is not minimum allocation size aligned, then there must be a gap that is added to the dynamic size. The dynamic size will never be smaller than the set value. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:09 -04:00

2017-07-12 11:27:32 -07:00

percpu: allocation size should be even 723ad1d90b56 ("percpu: store offsets instead of lengths in ->map[]") updated percpu area allocator to use the lowest bit, instead of sign, to signify whether the area is occupied and forced min align to 2; unfortunately, it forgot to force the allocation size to be even causing malfunctions for the very rare odd-sized allocations. Always force the allocations to be even sized. tj: Wrote patch description. Original-patch-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tejun Heo <tj@kernel.org>

2014-03-17 16:01:27 -04:00

percpu: ensure the requested alignment is power of two The percpu allocator expectedly assumes that the requested alignment is power of two but hasn't been veryfing the input. If the specified alignment isn't power of two, the allocator can malfunction. Add the sanity check. The following is detailed analysis of the effects of alignments which aren't power of two. The alignment must be a even at least since the LSB of a chunk->map element is used as free/in-use flag of a area; besides, the alignment must be a power of 2 too since ALIGN() doesn't work well for other alignment always but is adopted by pcpu_fit_in_area(). IOW, the current allocator only works well for a power of 2 aligned area allocation. See below opposite example for why an odd alignment doesn't work. Let's assume area [16, 36) is free but its previous one is in-use, we want to allocate a @size == 8 and @align == 7 area. The larger area [16, 36) is split to three areas [16, 21), [21, 29), [29, 36) eventually. However, due to the usage for a chunk->map element, the actual offset of the aim area [21, 29) is 21 but is recorded in relevant element as 20; moreover, the residual tail free area [29, 36) is mistook as in-use and is lost silently Unlike macro roundup(), ALIGN(x, a) doesn't work if @a isn't a power of 2 for example, roundup(10, 6) == 12 but ALIGN(10, 6) == 10, and the latter result isn't desired obviously. tj: Code style and patch description updates. Signed-off-by: zijun_hu <zijun_hu@htc.com> Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org>

2016-10-14 15:12:54 +08:00

mm, percpu: add support for __GFP_NOWARN flag Add an option for pcpu_alloc() to support __GFP_NOWARN flag. Currently, we always throw a warning when size or alignment is unsupported (and also dump stack on failed allocation requests). The warning itself is harmless since we return NULL anyway for any failed request, which callers are required to handle anyway. However, it becomes harmful when panic_on_warn is set. The rationale for the WARN() in pcpu_alloc() is that it can be tracked when larger than supported allocation requests are made such that allocations limits can be tweaked if warranted. This makes sense for in-kernel users, however, there are users of pcpu allocator where allocation size is derived from user space requests, e.g. when creating BPF maps. In these cases, the requests should fail gracefully without throwing a splat. The current work-around was to check allocation size against the upper limit of PCPU_MIN_UNIT_SIZE from call-sites for bailing out prior to a call to pcpu_alloc() in order to avoid throwing the WARN(). This is bad in multiple ways since PCPU_MIN_UNIT_SIZE is an implementation detail, and having the checks on call-sites only complicates the code for no good reason. Thus, lets fix it generically by supporting the __GFP_NOWARN flag that users can then use with calling the __alloc_percpu_gfp() helper instead. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>

2017-10-17 16:55:52 +02:00

mm: coalesce split strings Kernel style prefers a single string over split strings when the string is 'user-visible'. Miscellanea: - Add a missing newline - Realign arguments Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> [percpu] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:47 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: Allow to kill tasks doing pcpu_alloc() and waiting for pcpu_balance_workfn() In case of memory deficit and low percpu memory pages, pcpu_balance_workfn() takes pcpu_alloc_mutex for a long time (as it makes memory allocations itself and waits for memory reclaim). If tasks doing pcpu_alloc() are choosen by OOM killer, they can't exit, because they are waiting for the mutex. The patch makes pcpu_alloc() to care about killing signal and use mutex_lock_killable(), when it's allowed by GFP flags. This guarantees, a task does not miss SIGKILL from OOM killer. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-03-19 18:32:10 +03:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: Allow to kill tasks doing pcpu_alloc() and waiting for pcpu_balance_workfn() In case of memory deficit and low percpu memory pages, pcpu_balance_workfn() takes pcpu_alloc_mutex for a long time (as it makes memory allocations itself and waits for memory reclaim). If tasks doing pcpu_alloc() are choosen by OOM killer, they can't exit, because they are waiting for the mutex. The patch makes pcpu_alloc() to care about killing signal and use mutex_lock_killable(), when it's allowed by GFP flags. This guarantees, a task does not miss SIGKILL from OOM killer. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-03-19 18:32:10 +03:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: Allow to kill tasks doing pcpu_alloc() and waiting for pcpu_balance_workfn() In case of memory deficit and low percpu memory pages, pcpu_balance_workfn() takes pcpu_alloc_mutex for a long time (as it makes memory allocations itself and waits for memory reclaim). If tasks doing pcpu_alloc() are choosen by OOM killer, they can't exit, because they are waiting for the mutex. The patch makes pcpu_alloc() to care about killing signal and use mutex_lock_killable(), when it's allowed by GFP flags. This guarantees, a task does not miss SIGKILL from OOM killer. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-03-19 18:32:10 +03:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm: Allow to kill tasks doing pcpu_alloc() and waiting for pcpu_balance_workfn() In case of memory deficit and low percpu memory pages, pcpu_balance_workfn() takes pcpu_alloc_mutex for a long time (as it makes memory allocations itself and waits for memory reclaim). If tasks doing pcpu_alloc() are choosen by OOM killer, they can't exit, because they are waiting for the mutex. The patch makes pcpu_alloc() to care about killing signal and use mutex_lock_killable(), when it's allowed by GFP flags. This guarantees, a task does not miss SIGKILL from OOM killer. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-03-19 18:32:10 +03:00

percpu: fix synchronization between synchronous map extension and chunk destruction For non-atomic allocations, pcpu_alloc() can try to extend the area map synchronously after dropping pcpu_lock; however, the extension wasn't synchronized against chunk destruction and the chunk might get freed while extension is in progress. This patch fixes the bug by putting most of non-atomic allocations under pcpu_alloc_mutex to synchronize against pcpu_balance_work which is responsible for async chunk management including destruction. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Reported-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: stable@vger.kernel.org # v3.18+ Fixes: 1a4d76076cda ("percpu: implement asynchronous chunk population")

2016-05-25 11:48:25 -04:00

percpu: allow pcpu_alloc() to be called with IRQs off pcpu_alloc() and pcpu_extend_area_map() perform a series of spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe with respect to being called from contexts which have IRQs off. This patch converts the code to perform save/restore of flags instead, making pcpu_alloc() (or __alloc_percpu() respectively) to be called from early kernel startup stage, where IRQs are off. This is needed for proper initialization of per-cpu rq_weight data from sched_init(). tj: added comment explaining why irqsave/restore is used in alloc path. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Tejun Heo <tj@kernel.org>

2009-10-29 00:25:59 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

2017-07-12 11:27:32 -07:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: make allocation failures more verbose Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-29 09:17:58 +09:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

2017-07-12 11:27:32 -07:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability pcpu_extend_area_map() had the following two bugs. * It should return 1 if pcpu_lock was dropped and reacquired but it returned 0. This could lead to oops if free_percpu() races with area map extension. * pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might end up calling vfree() which isn't IRQ safe. This could lead to deadlock through lock order inversion via IRQ. In addition, Linus pointed out that the temporary lock dropping and subtle three-way return value of pcpu_extend_area_map() was very ugly and suggested to split the function into two - pcpu_need_to_extend() and pcpu_extend_area_map(). This patch restructures pcpu_extend_area_map() as suggested and fixes the two bugs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-11-11 15:35:18 +09:00

percpu: make allocation failures more verbose Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-29 09:17:58 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

2017-07-12 11:27:32 -07:00

percpu: relegate chunks unusable when failing small allocations In certain cases, requestors of percpu memory may want specific alignments. However, it is possible to end up in situations where the contig_hint matches, but the alignment does not. This causes excess scanning of chunks that will fail. To prevent this, if a small allocation fails (< 32B), the chunk is moved to the empty list. Once an allocation is freed from that chunk, it is placed back into rotation. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 09:03:50 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: relegate chunks unusable when failing small allocations In certain cases, requestors of percpu memory may want specific alignments. However, it is possible to end up in situations where the contig_hint matches, but the alignment does not. This causes excess scanning of chunks that will fail. To prevent this, if a small allocation fails (< 32B), the chunk is moved to the empty list. Once an allocation is freed from that chunk, it is placed back into rotation. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-25 09:03:50 -08:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

2017-07-12 11:27:32 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: allow pcpu_alloc() to be called with IRQs off pcpu_alloc() and pcpu_extend_area_map() perform a series of spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe with respect to being called from contexts which have IRQs off. This patch converts the code to perform save/restore of flags instead, making pcpu_alloc() (or __alloc_percpu() respectively) to be called from early kernel startup stage, where IRQs are off. This is needed for proper initialization of per-cpu rq_weight data from sched_init(). tj: added comment explaining why irqsave/restore is used in alloc path. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Tejun Heo <tj@kernel.org>

2009-10-29 00:25:59 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: resolve err may not be initialized in pcpu_alloc From 4a42ecc735cff0015cc73c3d87edede631f4b885 Mon Sep 17 00:00:00 2001 From: Dennis Zhou <dennisz@fb.com> Date: Wed, 21 Jun 2017 08:07:15 -0700 Add error message to out of space failure for atomic allocations in percpu allocation path to fix -Wmaybe-uninitialized. Signed-off-by: Dennis Zhou <dennisz@fb.com> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-21 11:51:09 -04:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: resolve err may not be initialized in pcpu_alloc From 4a42ecc735cff0015cc73c3d87edede631f4b885 Mon Sep 17 00:00:00 2001 From: Dennis Zhou <dennisz@fb.com> Date: Wed, 21 Jun 2017 08:07:15 -0700 Add error message to out of space failure for atomic allocations in percpu allocation path to fix -Wmaybe-uninitialized. Signed-off-by: Dennis Zhou <dennisz@fb.com> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-21 11:51:09 -04:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

mm/percpu: Update the code comment when creating new chunk The lock pcpu_alloc_mutex taking code has been moved to the beginning of pcpu_allo() if it's non atomic allocation. So the code comment above above pcpu_create_chunk() callsite need be updated. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2022-10-24 16:14:30 +08:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: restructure locking At first, the percpu allocator required a sleepable context for both alloc and free paths and used pcpu_alloc_mutex to protect everything. Later, pcpu_lock was introduced to protect the index data structure so that the free path can be invoked from atomic contexts. The conversion only updated what's necessary and left most of the allocation path under pcpu_alloc_mutex. The percpu allocator is planned to add support for atomic allocation and this patch restructures locking so that the coverage of pcpu_alloc_mutex is further reduced. * pcpu_alloc() now grab pcpu_alloc_mutex only while creating a new chunk and populating the allocated area. Everything else is now protected soley by pcpu_lock. After this change, multiple instances of pcpu_extend_area_map() may race but the function already implements sufficient synchronization using pcpu_lock. This also allows multiple allocators to arrive at new chunk creation. To avoid creating multiple empty chunks back-to-back, a new chunk is created iff there is no other empty chunk after grabbing pcpu_alloc_mutex. * pcpu_lock is now held while modifying chunk->populated bitmap. After this, all data structures are protected by pcpu_lock. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

percpu: make allocation failures more verbose Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-29 09:17:58 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: expose statistics about percpu memory via debugfs There is limited visibility into the use of percpu memory leaving us unable to reason about correctness of parameters and overall use of percpu memory. These counters and statistics aim to help understand basic statistics about percpu memory such as number of allocations over the lifetime, allocation sizes, and fragmentation. New Config: PERCPU_STATS Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:31 -04:00

percpu: allow pcpu_alloc() to be called with IRQs off pcpu_alloc() and pcpu_extend_area_map() perform a series of spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe with respect to being called from contexts which have IRQs off. This patch converts the code to perform save/restore of flags instead, making pcpu_alloc() (or __alloc_percpu() respectively) to be called from early kernel startup stage, where IRQs are off. This is needed for proper initialization of per-cpu rq_weight data from sched_init(). tj: added comment explaining why irqsave/restore is used in alloc path. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Tejun Heo <tj@kernel.org>

2009-10-29 00:25:59 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: move common parts out of pcpu_[de]populate_chunk() percpu-vm and percpu-km implement separate versions of pcpu_[de]populate_chunk() and some part which is or should be common are currently in the specific implementations. Make the following changes. * Allocate area clearing is moved from the pcpu_populate_chunk() implementations to pcpu_alloc(). This makes percpu-km's version noop. * Quick exit tests in pcpu_[de]populate_chunk() of percpu-vm are moved to their respective callers so that they are applied to percpu-km too. This doesn't make any meaningful difference as both functions are noop for percpu-km; however, this is more consistent and will help implementing atomic allocation support. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:01 -04:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

bitmap: unify find_bit operations bitmap_for_each_{set,clear}_region() are similar to for_each_bit() macros in include/linux/find.h, but interface and implementation of them are different. This patch adds for_each_bitrange() macros and drops unused bitmap_*_region() API in sake of unification. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC

2021-08-14 14:17:11 -07:00

percpu: move common parts out of pcpu_[de]populate_chunk() percpu-vm and percpu-km implement separate versions of pcpu_[de]populate_chunk() and some part which is or should be common are currently in the specific implementations. Make the following changes. * Allocate area clearing is moved from the pcpu_populate_chunk() implementations to pcpu_alloc(). This makes percpu-km's version noop. * Quick exit tests in pcpu_[de]populate_chunk() of percpu-vm are moved to their respective callers so that they are applied to percpu-km too. This doesn't make any meaningful difference as both functions are noop for percpu-km; however, this is more consistent and will help implementing atomic allocation support. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:01 -04:00

bitmap: unify find_bit operations bitmap_for_each_{set,clear}_region() are similar to for_each_bit() macros in include/linux/find.h, but interface and implementation of them are different. This patch adds for_each_bitrange() macros and drops unused bitmap_*_region() API in sake of unification. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC

2021-08-14 14:17:11 -07:00

percpu: indent the population block in pcpu_alloc() The next patch will conditionalize the population block in pcpu_alloc() which will end up making a rather large indentation change obfuscating the actual logic change. This patch puts the block under "if (true)" so that the next patch can avoid indentation changes. The defintions of the local variables which are used only in the block are moved into the block. This patch is purely cosmetic. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: restructure locking At first, the percpu allocator required a sleepable context for both alloc and free paths and used pcpu_alloc_mutex to protect everything. Later, pcpu_lock was introduced to protect the index data structure so that the free path can be invoked from atomic contexts. The conversion only updated what's necessary and left most of the allocation path under pcpu_alloc_mutex. The percpu allocator is planned to add support for atomic allocation and this patch restructures locking so that the coverage of pcpu_alloc_mutex is further reduced. * pcpu_alloc() now grab pcpu_alloc_mutex only while creating a new chunk and populating the allocated area. Everything else is now protected soley by pcpu_lock. After this change, multiple instances of pcpu_extend_area_map() may race but the function already implements sufficient synchronization using pcpu_lock. This also allows multiple allocators to arrive at new chunk creation. To avoid creating multiple empty chunks back-to-back, a new chunk is created iff there is no other empty chunk after grabbing pcpu_alloc_mutex. * pcpu_lock is now held while modifying chunk->populated bitmap. After this, all data structures are protected by pcpu_lock. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

bitmap: unify find_bit operations bitmap_for_each_{set,clear}_region() are similar to for_each_bit() macros in include/linux/find.h, but interface and implementation of them are different. This patch adds for_each_bitrange() macros and drops unused bitmap_*_region() API in sake of unification. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC

2021-08-14 14:17:11 -07:00

percpu: indent the population block in pcpu_alloc() The next patch will conditionalize the population block in pcpu_alloc() which will end up making a rather large indentation change obfuscating the actual logic change. This patch puts the block under "if (true)" so that the next patch can avoid indentation changes. The defintions of the local variables which are used only in the block are moved into the block. This patch is purely cosmetic. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: allow select gfp to be passed to underlying allocators The prior patch added support for passing gfp flags through to the underlying allocators. This patch allows users to pass along gfp flags (currently only __GFP_NORETRY and __GFP_NOWARN) to the underlying allocators. This should allow users to decide if they are ok with failing allocations recovering in a more graceful way. Additionally, gfp passing was done as additional flags in the previous patch. Instead, change this to caller passed semantics. GFP_KERNEL is also removed as the default flag. It continues to be used for internally caused underlying percpu allocations. V2: Removed gfp_percpu_mask in favor of doing it inline. Removed GFP_KERNEL as a default flag for __alloc_percpu_gfp. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:09:58 -06:00

percpu: indent the population block in pcpu_alloc() The next patch will conditionalize the population block in pcpu_alloc() which will end up making a rather large indentation change obfuscating the actual logic change. This patch puts the block under "if (true)" so that the next patch can avoid indentation changes. The defintions of the local variables which are used only in the block are moved into the block. This patch is purely cosmetic. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

2017-07-12 11:27:32 -07:00

percpu: indent the population block in pcpu_alloc() The next patch will conditionalize the population block in pcpu_alloc() which will end up making a rather large indentation change obfuscating the actual logic change. This patch puts the block under "if (true)" so that the next patch can avoid indentation changes. The defintions of the local variables which are used only in the block are moved into the block. This patch is purely cosmetic. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: indent the population block in pcpu_alloc() The next patch will conditionalize the population block in pcpu_alloc() which will end up making a rather large indentation change obfuscating the actual logic change. This patch puts the block under "if (true)" so that the next patch can avoid indentation changes. The defintions of the local variables which are used only in the block are moved into the block. This patch is purely cosmetic. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: move common parts out of pcpu_[de]populate_chunk() percpu-vm and percpu-km implement separate versions of pcpu_[de]populate_chunk() and some part which is or should be common are currently in the specific implementations. Make the following changes. * Allocate area clearing is moved from the pcpu_populate_chunk() implementations to pcpu_alloc(). This makes percpu-km's version noop. * Quick exit tests in pcpu_[de]populate_chunk() of percpu-vm are moved to their respective callers so that they are applied to percpu-km too. This doesn't make any meaningful difference as both functions are noop for percpu-km; however, this is more consistent and will help implementing atomic allocation support. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:01 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: indent the population block in pcpu_alloc() The next patch will conditionalize the population block in pcpu_alloc() which will end up making a rather large indentation change obfuscating the actual logic change. This patch puts the block under "if (true)" so that the next patch can avoid indentation changes. The defintions of the local variables which are used only in the block are moved into the block. This patch is purely cosmetic. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: move common parts out of pcpu_[de]populate_chunk() percpu-vm and percpu-km implement separate versions of pcpu_[de]populate_chunk() and some part which is or should be common are currently in the specific implementations. Make the following changes. * Allocate area clearing is moved from the pcpu_populate_chunk() implementations to pcpu_alloc(). This makes percpu-km's version noop. * Quick exit tests in pcpu_[de]populate_chunk() of percpu-vm are moved to their respective callers so that they are applied to percpu-km too. This doesn't make any meaningful difference as both functions are noop for percpu-km; however, this is more consistent and will help implementing atomic allocation support. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:01 -04:00

kmemleak: Handle percpu memory allocation This patch adds kmemleak callbacks from the percpu allocator, reducing a number of false positives caused by kmemleak not scanning such memory blocks. The percpu chunks are never reported as leaks because of current kmemleak limitations with the __percpu pointer not pointing directly to the actual chunks. Reported-by: Huajun Li <huajun.li.lee@gmail.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2011-09-26 17:12:53 +01:00

mm: kmemleak_alloc_percpu() should follow the gfp from per_alloc() Beginning at commit d52d3997f843 ("ipv6: Create percpu rt6_info"), the following INFO splat is logged: =============================== [ INFO: suspicious RCU usage. ] 4.1.0-rc7-next-20150612 #1 Not tainted ------------------------------- kernel/sched/core.c:7318 Illegal context switch in RCU-bh read-side critical section! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 3 locks held by systemd/1: #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff815f0c8f>] rtnetlink_rcv+0x1f/0x40 #1: (rcu_read_lock_bh){......}, at: [<ffffffff816a34e2>] ipv6_add_addr+0x62/0x540 #2: (addrconf_hash_lock){+...+.}, at: [<ffffffff816a3604>] ipv6_add_addr+0x184/0x540 stack backtrace: CPU: 0 PID: 1 Comm: systemd Not tainted 4.1.0-rc7-next-20150612 #1 Hardware name: TOSHIBA TECRA A50-A/TECRA A50-A, BIOS Version 4.20 04/17/2014 Call Trace: dump_stack+0x4c/0x6e lockdep_rcu_suspicious+0xe7/0x120 ___might_sleep+0x1d5/0x1f0 __might_sleep+0x4d/0x90 kmem_cache_alloc+0x47/0x250 create_object+0x39/0x2e0 kmemleak_alloc_percpu+0x61/0xe0 pcpu_alloc+0x370/0x630 Additional backtrace lines are truncated. In addition, the above splat is followed by several "BUG: sleeping function called from invalid context at mm/slub.c:1268" outputs. As suggested by Martin KaFai Lau, these are the clue to the fix. Routine kmemleak_alloc_percpu() always uses GFP_KERNEL for its allocations, whereas it should follow the gfp from its callers. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: <stable@vger.kernel.org> [3.18+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2015-06-24 16:58:51 -07:00

percpu: add tracepoint support for percpu memory Add support for tracepoints to the following events: chunk allocation, chunk free, area allocation, area free, and area allocation failure. This should let us replay percpu memory requests and evaluate corresponding decisions. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:32 -04:00

percpu: improve percpu_alloc_percpu event trace Add call_site, bytes_alloc and gfp_flags fields to the output of the percpu_alloc_percpu ftrace event: mkdir-4393 [001] 169.334788: percpu_alloc_percpu: call_site=mem_cgroup_css_alloc+0xa6 reserved=0 is_atomic=0 size=2408 align=8 base_addr=0xffffc7117fc00000 off=402176 ptr=0x3dc867a62300 bytes_alloc=14448 gfp_flags=GFP_KERNEL_ACCOUNT This is required to track memcg-accounted percpu allocations. Link: https://lkml.kernel.org/r/a07be858-c8a3-7851-9086-e3262cbcf707@openvz.org Signed-off-by: Vasily Averin <vvs@openvz.org> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2022-05-12 20:23:07 -07:00

percpu: add tracepoint support for percpu memory Add support for tracepoints to the following events: chunk allocation, chunk free, area allocation, area free, and area allocation failure. This should let us replay percpu memory requests and evaluate corresponding decisions. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:32 -04:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

kmemleak: Handle percpu memory allocation This patch adds kmemleak callbacks from the percpu allocator, reducing a number of false positives caused by kmemleak not scanning such memory blocks. The percpu chunks are never reported as leaks because of current kmemleak limitations with the __percpu pointer not pointing directly to the actual chunks. Reported-by: Huajun Li <huajun.li.lee@gmail.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2011-09-26 17:12:53 +01:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: allow pcpu_alloc() to be called with IRQs off pcpu_alloc() and pcpu_extend_area_map() perform a series of spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe with respect to being called from contexts which have IRQs off. This patch converts the code to perform save/restore of flags instead, making pcpu_alloc() (or __alloc_percpu() respectively) to be called from early kernel startup stage, where IRQs are off. This is needed for proper initialization of per-cpu rq_weight data from sched_init(). tj: added comment explaining why irqsave/restore is used in alloc path. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Tejun Heo <tj@kernel.org>

2009-10-29 00:25:59 +09:00

percpu: restructure locking At first, the percpu allocator required a sleepable context for both alloc and free paths and used pcpu_alloc_mutex to protect everything. Later, pcpu_lock was introduced to protect the index data structure so that the free path can be invoked from atomic contexts. The conversion only updated what's necessary and left most of the allocation path under pcpu_alloc_mutex. The percpu allocator is planned to add support for atomic allocation and this patch restructures locking so that the coverage of pcpu_alloc_mutex is further reduced. * pcpu_alloc() now grab pcpu_alloc_mutex only while creating a new chunk and populating the allocated area. Everything else is now protected soley by pcpu_lock. After this change, multiple instances of pcpu_extend_area_map() may race but the function already implements sufficient synchronization using pcpu_lock. This also allows multiple allocators to arrive at new chunk creation. To avoid creating multiple empty chunks back-to-back, a new chunk is created iff there is no other empty chunk after grabbing pcpu_alloc_mutex. * pcpu_lock is now held while modifying chunk->populated bitmap. After this, all data structures are protected by pcpu_lock. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

percpu: add tracepoint support for percpu memory Add support for tracepoints to the following events: chunk allocation, chunk free, area allocation, area free, and area allocation failure. This should let us replay percpu memory requests and evaluate corresponding decisions. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:32 -04:00

mm/percpu.c: print error message too if atomic alloc failed The variable 'err' is assgigned to an error message if atomic alloc failed, while it has no chance to be printed if is_atomic is true. Here change to print error message too if atomic alloc failed, while avoid to call dump_stack() if that case. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-28 11:02:55 +08:00

mm: percpu: use pr_fmt to prefix output Use the normal mechanism to make the logging output consistently "percpu:" instead of a mix of "PERCPU:" and "percpu:" Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:53 -07:00

mm: convert pr_warning to pr_warn There are a mixture of pr_warning and pr_warn uses in mm. Use pr_warn consistently. Miscellanea: - Coalesce formats - Realign arguments Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> [percpu] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:44 -07:00

mm/percpu.c: print error message too if atomic alloc failed The variable 'err' is assgigned to an error message if atomic alloc failed, while it has no chance to be printed if is_atomic is true. Here change to print error message too if atomic alloc failed, while avoid to call dump_stack() if that case. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-28 11:02:55 +08:00

percpu: make allocation failures more verbose Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-29 09:17:58 +09:00

mm: percpu: use pr_fmt to prefix output Use the normal mechanism to make the logging output consistently "percpu:" instead of a mix of "PERCPU:" and "percpu:" Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:53 -07:00

percpu: make allocation failures more verbose Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-29 09:17:58 +09:00

mm/percpu.c: print error message too if atomic alloc failed The variable 'err' is assgigned to an error message if atomic alloc failed, while it has no chance to be printed if is_atomic is true. Here change to print error message too if atomic alloc failed, while avoid to call dump_stack() if that case. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-28 11:02:55 +08:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

mm: fix typos in comments Fix ~94 single-word typos in locking code comments, plus a few very obvious grammar mistakes. Link: https://lkml.kernel.org/r/20210322212624.GA1963421@gmail.com Link: https://lore.kernel.org/r/20210322205203.GB1959563@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2021-05-06 18:06:47 -07:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: fix synchronization between synchronous map extension and chunk destruction For non-atomic allocations, pcpu_alloc() can try to extend the area map synchronously after dropping pcpu_lock; however, the extension wasn't synchronized against chunk destruction and the chunk might get freed while extension is in progress. This patch fixes the bug by putting most of non-atomic allocations under pcpu_alloc_mutex to synchronize against pcpu_balance_work which is responsible for async chunk management including destruction. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Reported-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: stable@vger.kernel.org # v3.18+ Fixes: 1a4d76076cda ("percpu: implement asynchronous chunk population")

2016-05-25 11:48:25 -04:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

mm, percpu: add support for __GFP_NOWARN flag Add an option for pcpu_alloc() to support __GFP_NOWARN flag. Currently, we always throw a warning when size or alignment is unsupported (and also dump stack on failed allocation requests). The warning itself is harmless since we return NULL anyway for any failed request, which callers are required to handle anyway. However, it becomes harmful when panic_on_warn is set. The rationale for the WARN() in pcpu_alloc() is that it can be tracked when larger than supported allocation requests are made such that allocations limits can be tweaked if warranted. This makes sense for in-kernel users, however, there are users of pcpu allocator where allocation size is derived from user space requests, e.g. when creating BPF maps. In these cases, the requests should fail gracefully without throwing a splat. The current work-around was to check allocation size against the upper limit of PCPU_MIN_UNIT_SIZE from call-sites for bailing out prior to a call to pcpu_alloc() in order to avoid throwing the WARN(). This is bad in multiple ways since PCPU_MIN_UNIT_SIZE is an implementation detail, and having the checks on call-sites only complicates the code for no good reason. Thus, lets fix it generically by supporting the __GFP_NOWARN flag that users can then use with calling the __alloc_percpu_gfp() helper instead. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>

2017-10-17 16:55:52 +02:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu: add __percpu sparse annotations to core kernel subsystems Add __percpu sparse annotations to core subsystems. These annotations are to make sparse consider percpu variables to be in a different address space and warn if accessed without going through percpu accessors. This patch doesn't affect normal builds. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-mm@kvack.org Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Eric Biederman <ebiederm@xmission.com>

2010-02-02 14:38:57 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: update comments to reflect that percpu allocations are always zero-filled Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Stephane Eranian <eranian@google.com>

2010-09-10 11:01:56 +02:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: add __percpu sparse annotations to core kernel subsystems Add __percpu sparse annotations to core subsystems. These annotations are to make sparse consider percpu variables to be in a different address space and warn if accessed without going through percpu accessors. This patch doesn't affect normal builds. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-mm@kvack.org Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Eric Biederman <ebiederm@xmission.com>

2010-02-02 14:38:57 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: implement [__]alloc_percpu_gfp() Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:04 -04:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: split __pcpu_balance_workfn() __pcpu_balance_workfn() became fairly big and hard to follow, but in fact it consists of two fully independent parts, responsible for the destruction of excessive free chunks and population of necessarily amount of free pages. In order to simplify the code and prepare for adding of a new functionality, split it in two functions: 1) pcpu_balance_free, 2) pcpu_balance_populated. Move the taking/releasing of the pcpu_alloc_mutex to an upper level to keep the current synchronization in place. Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:32 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: rename pcpu_reclaim_work to pcpu_balance_work pcpu_reclaim_work will also be used to populate chunks asynchronously. Rename it to pcpu_balance_work in preparation. pcpu_reclaim() is renamed to pcpu_balance_workfn() and some of its local variables are renamed too. This is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: rename pcpu_reclaim_work to pcpu_balance_work pcpu_reclaim_work will also be used to populate chunks asynchronously. Rename it to pcpu_balance_work in preparation. pcpu_reclaim() is renamed to pcpu_balance_workfn() and some of its local variables are renamed too. This is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: rename pcpu_reclaim_work to pcpu_balance_work pcpu_reclaim_work will also be used to populate chunks asynchronously. Rename it to pcpu_balance_work in preparation. pcpu_reclaim() is renamed to pcpu_balance_workfn() and some of its local variables are renamed too. This is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: rename pcpu_reclaim_work to pcpu_balance_work pcpu_reclaim_work will also be used to populate chunks asynchronously. Rename it to pcpu_balance_work in preparation. pcpu_reclaim() is renamed to pcpu_balance_workfn() and some of its local variables are renamed too. This is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

bitmap: genericize percpu bitmap region iterators Bitmaps are fairly popular for their space efficiency, but we don't have generic iterators available. Make percpu's bitmap region iterators available to everyone. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>

2019-12-13 16:22:10 -08:00

percpu: move common parts out of pcpu_[de]populate_chunk() percpu-vm and percpu-km implement separate versions of pcpu_[de]populate_chunk() and some part which is or should be common are currently in the specific implementations. Make the following changes. * Allocate area clearing is moved from the pcpu_populate_chunk() implementations to pcpu_alloc(). This makes percpu-km's version noop. * Quick exit tests in pcpu_[de]populate_chunk() of percpu-vm are moved to their respective callers so that they are applied to percpu-km too. This doesn't make any meaningful difference as both functions are noop for percpu-km; however, this is more consistent and will help implementing atomic allocation support. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:01 -04:00

bitmap: unify find_bit operations bitmap_for_each_{set,clear}_region() are similar to for_each_bit() macros in include/linux/find.h, but interface and implementation of them are different. This patch adds for_each_bitrange() macros and drops unused bitmap_*_region() API in sake of unification. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC

2021-08-14 14:17:11 -07:00

percpu: move region iterations out of pcpu_[de]populate_chunk() Previously, pcpu_[de]populate_chunk() were called with the range which may contain multiple target regions in it and pcpu_[de]populate_chunk() iterated over the regions. This has the benefit of batching up cache flushes for all the regions; however, we're planning to add more bookkeeping logic around [de]population to support atomic allocations and this delegation of iterations gets in the way. This patch moves the region iterations out of pcpu_[de]populate_chunk() into its callers - pcpu_alloc() and pcpu_reclaim() - so that we can later add logic to track more states around them. This change may make cache and tlb flushes more frequent but multi-region [de]populations are rare anyway and if this actually becomes a problem, it's not difficult to factor out cache flushes as separate callbacks which are directly invoked from percpu.c. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated pcpu_nr_empty_pop_pages counts the number of empty populated pages across all chunks and chunk->nr_populated counts the number of populated pages in a chunk. Both will be used to implement pre/async population for atomic allocations. pcpu_chunk_[de]populated() are added to update chunk->populated, chunk->nr_populated and pcpu_nr_empty_pop_pages together. All successful chunk [de]populations should be followed by the corresponding pcpu_chunk_[de]populated() calls. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: move region iterations out of pcpu_[de]populate_chunk() Previously, pcpu_[de]populate_chunk() were called with the range which may contain multiple target regions in it and pcpu_[de]populate_chunk() iterated over the regions. This has the benefit of batching up cache flushes for all the regions; however, we're planning to add more bookkeeping logic around [de]population to support atomic allocations and this delegation of iterations gets in the way. This patch moves the region iterations out of pcpu_[de]populate_chunk() into its callers - pcpu_alloc() and pcpu_reclaim() - so that we can later add logic to track more states around them. This change may make cache and tlb flushes more frequent but multi-region [de]populations are rare anyway and if this actually becomes a problem, it's not difficult to factor out cache flushes as separate callbacks which are directly invoked from percpu.c. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:02 -04:00

percpu: reorganize chunk creation and destruction Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free live in pcpu_alloc/free_chunk() and the rest in pcpu_create/destroy_chunk(). While at it, add missing error handling for chunk->map allocation failure. This is to allow alternate chunk management implementation for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: add a schedule point in pcpu_balance_workfn() When a large BPF percpu map is destroyed, I have seen pcpu_balance_workfn() holding cpu for hundreds of milliseconds. On KASAN config and 112 hyperthreads, average time to destroy a chunk is ~4 ms. [ 2489.841376] destroy chunk 1 in 4148689 ns ... [ 2490.093428] destroy chunk 32 in 4072718 ns Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-23 08:12:42 -08:00

percpu: move fully free chunk reclamation into a work Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-07 00:44:11 +09:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: split __pcpu_balance_workfn() __pcpu_balance_workfn() became fairly big and hard to follow, but in fact it consists of two fully independent parts, responsible for the destruction of excessive free chunks and population of necessarily amount of free pages. In order to simplify the code and prepare for adding of a new functionality, split it in two functions: 1) pcpu_balance_free, 2) pcpu_balance_populated. Move the taking/releasing of the pcpu_alloc_mutex to an upper level to keep the current synchronization in place. Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:32 -07:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: split __pcpu_balance_workfn() __pcpu_balance_workfn() became fairly big and hard to follow, but in fact it consists of two fully independent parts, responsible for the destruction of excessive free chunks and population of necessarily amount of free pages. In order to simplify the code and prepare for adding of a new functionality, split it in two functions: 1) pcpu_balance_free, 2) pcpu_balance_populated. Move the taking/releasing of the pcpu_alloc_mutex to an upper level to keep the current synchronization in place. Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:32 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: split __pcpu_balance_workfn() __pcpu_balance_workfn() became fairly big and hard to follow, but in fact it consists of two fully independent parts, responsible for the destruction of excessive free chunks and population of necessarily amount of free pages. In order to simplify the code and prepare for adding of a new functionality, split it in two functions: 1) pcpu_balance_free, 2) pcpu_balance_populated. Move the taking/releasing of the pcpu_alloc_mutex to an upper level to keep the current synchronization in place. Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:32 -07:00

percpu: fix pcpu_reclaim() locking pcpu_reclaim() calls pcpu_depopulate_chunk() which makes use of pages array and bitmap returned by pcpu_get_pages_and_bitmap() and thus should be called under pcpu_alloc_mutex. pcpu_reclaim() released the mutex before calling depopulate leading to double free and other strange problems caused by the unexpected concurrent usages of pages array and bitmap. Fix it. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org>

2009-08-14 15:00:49 +09:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: fix pcpu_reclaim() locking pcpu_reclaim() calls pcpu_depopulate_chunk() which makes use of pages array and bitmap returned by pcpu_get_pages_and_bitmap() and thus should be called under pcpu_alloc_mutex. pcpu_reclaim() released the mutex before calling depopulate leading to double free and other strange problems caused by the unexpected concurrent usages of pages array and bitmap. Fix it. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org>

2009-08-14 15:00:49 +09:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: use pcpu_free_slot instead of pcpu_nr_slots - 1 This prepares for adding a to_depopulate list and sidelined list after the free slot in the set of lists in pcpu_slot. Signed-off-by: Dennis Zhou <dennis@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-18 22:44:16 +00:00

bitmap: genericize percpu bitmap region iterators Bitmaps are fairly popular for their space efficiency, but we don't have generic iterators available. Make percpu's bitmap region iterators available to everyone. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>

2019-12-13 16:22:10 -08:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: change the number of pages marked in the first_chunk pop bitmap The populated bitmap represents the state of the pages the chunk serves. Prior, the bitmap was marked completely used as the first chunk was allocated and immutable. This is misleading because the first chunk may not be completely filled. Additionally, with moving the base_addr up in the previous patch, the population check no longer corresponds to what was being checked. This patch modifies the population map to be only the number of pages the region serves and to make what it was checking correspond correctly again. The change is to remove any misunderstanding between the size of the populated bitmap and the actual size of it. The work function page iterators now use nr_pages for the check rather than pcpu_unit_pages because nr_populated is now chunk specific. Without this, the work function would try to populate the remainder of these chunks despite it not serving any more than nr_pages when nr_pages is set less than pcpu_unit_pages. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:07 -04:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

bitmap: unify find_bit operations bitmap_for_each_{set,clear}_region() are similar to for_each_bit() macros in include/linux/find.h, but interface and implementation of them are different. This patch adds for_each_bitrange() macros and drops unused bitmap_*_region() API in sake of unification. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Acked-by: Dennis Zhou <dennis@kernel.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC

2021-08-14 14:17:11 -07:00

bitmap: genericize percpu bitmap region iterators Bitmaps are fairly popular for their space efficiency, but we don't have generic iterators available. Make percpu's bitmap region iterators available to everyone. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>

2019-12-13 16:22:10 -08:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: add __GFP_NORETRY semantics to the percpu balancing path Percpu memory using the vmalloc area based chunk allocator lazily populates chunks by first requesting the full virtual address space required for the chunk and subsequently adding pages as allocations come through. To ensure atomic allocations can succeed, a workqueue item is used to maintain a minimum number of empty pages. In certain scenarios, such as reported in [1], it is possible that physical memory becomes quite scarce which can result in either a rather long time spent trying to find free pages or worse, a kernel panic. This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them through to the underlying allocators. This should prevent any unnecessary panics potentially caused by the workqueue item. The passing of gfp around is as additional flags rather than a full set of flags. The next patch will change these to caller passed semantics. V2: Added const modifier to gfp flags in the balance path. Removed an extra whitespace. [1] https://lkml.org/lkml/2018/2/12/551 Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2018-02-16 12:07:19 -06:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>

2019-02-13 11:10:30 -08:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

mm/percpu: use list_first_entry_or_null in pcpu_reclaim_populated() To replace list_empty()/list_first_entry() pair to simplify code. Signed-off-by: Baoquan He <bhe@redhat.com> Acked-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2022-10-25 11:11:45 +08:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

mm/percpu: replace the goto with break In function pcpu_reclaim_populated(), the line of goto jumping is unnecessary since the label 'end_chunk' is near the end of the for loop, use break instead. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2022-10-24 16:14:32 +08:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: flush tlb in pcpu_reclaim_populated() Prior to "percpu: implement partial chunk depopulation", pcpu_depopulate_chunk() was called only on the destruction path. This meant the virtual address range was on its way back to vmalloc which will handle flushing the tlbs for us. However, with pcpu_reclaim_populated(), we are now calling pcpu_depopulate_chunk() during the active lifecycle of a chunk. Therefore, we need to flush the tlb as well otherwise we can end up accessing the wrong page through an invalid tlb mapping as reported in [1]. [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/ Fixes: f183324133ea ("percpu: implement partial chunk depopulation") Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-07-03 03:49:57 +00:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: optimize locking in pcpu_balance_workfn() pcpu_balance_workfn() unconditionally calls pcpu_balance_free(), pcpu_reclaim_populated(), pcpu_balance_populated() and pcpu_balance_free() again. Each call to pcpu_balance_free() and pcpu_reclaim_populated() will cause at least one acquisition of the pcpu_lock. So even if the balancing was scheduled because of a failed atomic allocation, pcpu_lock will be acquired at least 4 times. This obviously increases the contention on the pcpu_lock. To optimize the scheme let's grab the pcpu_lock on the upper level (in pcpu_balance_workfn()) and keep it generally locked for the whole duration of the scheduled work, but release conditionally to perform any slow operations like chunk (de)population and creation of new chunks. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-17 12:03:22 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm/percpu.c: introduce pcpu_alloc_size() Introduce pcpu_alloc_size() to get the size of the dynamic per-cpu area. It will be used by bpf memory allocator in the following patches. BPF memory allocator maintains per-cpu area caches for multiple area sizes and its free API only has the to-be-freed per-cpu pointer, so it needs the size of dynamic per-cpu area to select the corresponding cache when bpf program frees the dynamic per-cpu pointer. Acked-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231020133202.4043247-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2023-10-20 21:31:57 +08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: add __percpu sparse annotations to core kernel subsystems Add __percpu sparse annotations to core subsystems. These annotations are to make sparse consider percpu variables to be in a different address space and warn if accessed without going through percpu accessors. This patch doesn't affect normal builds. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-mm@kvack.org Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Eric Biederman <ebiederm@xmission.com>

2010-02-02 14:38:57 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: avoid calling __pcpu_ptr_to_addr(NULL) __pcpu_ptr_to_addr() can be overridden by the architecture and might not behave well if passed a NULL pointer. So avoid calling it until we have verified that its arg is not NULL. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2010-01-08 14:42:39 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: remove spurious lock dependency between percpu and sched In free_percpu() we sometimes call pcpu_schedule_balance_work() to queue a work item (which does a wakeup) while holding pcpu_lock. This creates an unnecessary lock dependency between pcpu_lock and the scheduler's pi_lock. There are other places where we call pcpu_schedule_balance_work() without hold pcpu_lock, and this case doesn't need to be different. Moving the call outside the lock prevents the following lockdep splat when running tools/testing/selftests/bpf/{test_maps,test_progs} in sequence with lockdep enabled: ====================================================== WARNING: possible circular locking dependency detected 5.1.0-dbg-DEV #1 Not tainted ------------------------------------------------------ kworker/23:255/18872 is trying to acquire lock: 000000000bc79290 (&(&pool->lock)->rlock){-.-.}, at: __queue_work+0xb2/0x520 but task is already holding lock: 00000000e3e7a6aa (pcpu_lock){..-.}, at: free_percpu+0x36/0x260 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (pcpu_lock){..-.}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 pcpu_alloc+0xfa/0x780 __alloc_percpu_gfp+0x12/0x20 alloc_htab_elem+0x184/0x2b0 __htab_percpu_map_update_elem+0x252/0x290 bpf_percpu_hash_update+0x7c/0x130 __do_sys_bpf+0x1912/0x1be0 __x64_sys_bpf+0x1a/0x20 do_syscall_64+0x59/0x400 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&htab->buckets[i].lock){....}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 htab_map_update_elem+0x1af/0x3a0 -> #2 (&rq->lock){-.-.}: lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 task_fork_fair+0x37/0x160 sched_fork+0x211/0x310 copy_process.part.43+0x7b1/0x2160 _do_fork+0xda/0x6b0 kernel_thread+0x29/0x30 rest_init+0x22/0x260 arch_call_rest_init+0xe/0x10 start_kernel+0x4fd/0x520 x86_64_start_reservations+0x24/0x26 x86_64_start_kernel+0x6f/0x72 secondary_startup_64+0xa4/0xb0 -> #1 (&p->pi_lock){-.-.}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 try_to_wake_up+0x41/0x600 wake_up_process+0x15/0x20 create_worker+0x16b/0x1e0 workqueue_init+0x279/0x2ee kernel_init_freeable+0xf7/0x288 kernel_init+0xf/0x180 ret_from_fork+0x24/0x30 -> #0 (&(&pool->lock)->rlock){-.-.}: __lock_acquire+0x101f/0x12a0 lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 __queue_work+0xb2/0x520 queue_work_on+0x38/0x80 free_percpu+0x221/0x260 pcpu_freelist_destroy+0x11/0x20 stack_map_free+0x2a/0x40 bpf_map_free_deferred+0x3c/0x50 process_one_work+0x1f7/0x580 worker_thread+0x54/0x410 kthread+0x10f/0x150 ret_from_fork+0x24/0x30 other info that might help us debug this: Chain exists of: &(&pool->lock)->rlock --> &htab->buckets[i].lock --> pcpu_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(pcpu_lock); lock(&htab->buckets[i].lock); lock(pcpu_lock); lock(&(&pool->lock)->rlock); *** DEADLOCK *** 3 locks held by kworker/23:255/18872: #0: 00000000b36a6e16 ((wq_completion)events){+.+.}, at: process_one_work+0x17a/0x580 #1: 00000000dfd966f0 ((work_completion)(&map->work)){+.+.}, at: process_one_work+0x17a/0x580 #2: 00000000e3e7a6aa (pcpu_lock){..-.}, at: free_percpu+0x36/0x260 stack backtrace: CPU: 23 PID: 18872 Comm: kworker/23:255 Not tainted 5.1.0-dbg-DEV #1 Hardware name: ... Workqueue: events bpf_map_free_deferred Call Trace: dump_stack+0x67/0x95 print_circular_bug.isra.38+0x1c6/0x220 check_prev_add.constprop.50+0x9f6/0xd20 __lock_acquire+0x101f/0x12a0 lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 __queue_work+0xb2/0x520 queue_work_on+0x38/0x80 free_percpu+0x221/0x260 pcpu_freelist_destroy+0x11/0x20 stack_map_free+0x2a/0x40 bpf_map_free_deferred+0x3c/0x50 process_one_work+0x1f7/0x580 worker_thread+0x54/0x410 kthread+0x10f/0x150 ret_from_fork+0x24/0x30 Signed-off-by: John Sperbeck <jsperbeck@google.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-05-07 18:43:20 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

kmemleak: Handle percpu memory allocation This patch adds kmemleak callbacks from the percpu allocator, reducing a number of false positives caused by kmemleak not scanning such memory blocks. The percpu chunks are never reported as leaks because of current kmemleak limitations with the __percpu pointer not pointing directly to the actual chunks. Reported-by: Huajun Li <huajun.li.lee@gmail.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2011-09-26 17:12:53 +01:00

percpu: avoid calling __pcpu_ptr_to_addr(NULL) __pcpu_ptr_to_addr() can be overridden by the architecture and might not behave well if passed a NULL pointer. So avoid calling it until we have verified that its arg is not NULL. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2010-01-08 14:42:39 -08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: add chunk->base_addr The only thing percpu allocator wants to know about a vmalloc area is the base address. Instead of requiring chunk->vm, add chunk->base_addr which contains the necessary value. This simplifies the code a bit and makes the dummy first_vm unnecessary. This change will ease allowing a chunk to be mapped by multiple vms. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

mm/percpu.c: don't acquire pcpu_lock for pcpu_chunk_addr_search() There is no need to acquire pcpu_lock for pcpu_chunk_addr_search(): 1) both pcpu_first_chunk & pcpu_reserved_chunk must have been initialized before the invocation of free_percpu(). 2) The dynamically-created chunk must be valid before the per-cpu pointers allocated from it are freed. So acquire pcpu_lock() after the invocation of pcpu_chunk_addr_search(). Acked-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231020133202.4043247-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2023-10-20 21:31:56 +08:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: remove spurious lock dependency between percpu and sched In free_percpu() we sometimes call pcpu_schedule_balance_work() to queue a work item (which does a wakeup) while holding pcpu_lock. This creates an unnecessary lock dependency between pcpu_lock and the scheduler's pi_lock. There are other places where we call pcpu_schedule_balance_work() without hold pcpu_lock, and this case doesn't need to be different. Moving the call outside the lock prevents the following lockdep splat when running tools/testing/selftests/bpf/{test_maps,test_progs} in sequence with lockdep enabled: ====================================================== WARNING: possible circular locking dependency detected 5.1.0-dbg-DEV #1 Not tainted ------------------------------------------------------ kworker/23:255/18872 is trying to acquire lock: 000000000bc79290 (&(&pool->lock)->rlock){-.-.}, at: __queue_work+0xb2/0x520 but task is already holding lock: 00000000e3e7a6aa (pcpu_lock){..-.}, at: free_percpu+0x36/0x260 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (pcpu_lock){..-.}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 pcpu_alloc+0xfa/0x780 __alloc_percpu_gfp+0x12/0x20 alloc_htab_elem+0x184/0x2b0 __htab_percpu_map_update_elem+0x252/0x290 bpf_percpu_hash_update+0x7c/0x130 __do_sys_bpf+0x1912/0x1be0 __x64_sys_bpf+0x1a/0x20 do_syscall_64+0x59/0x400 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&htab->buckets[i].lock){....}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 htab_map_update_elem+0x1af/0x3a0 -> #2 (&rq->lock){-.-.}: lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 task_fork_fair+0x37/0x160 sched_fork+0x211/0x310 copy_process.part.43+0x7b1/0x2160 _do_fork+0xda/0x6b0 kernel_thread+0x29/0x30 rest_init+0x22/0x260 arch_call_rest_init+0xe/0x10 start_kernel+0x4fd/0x520 x86_64_start_reservations+0x24/0x26 x86_64_start_kernel+0x6f/0x72 secondary_startup_64+0xa4/0xb0 -> #1 (&p->pi_lock){-.-.}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 try_to_wake_up+0x41/0x600 wake_up_process+0x15/0x20 create_worker+0x16b/0x1e0 workqueue_init+0x279/0x2ee kernel_init_freeable+0xf7/0x288 kernel_init+0xf/0x180 ret_from_fork+0x24/0x30 -> #0 (&(&pool->lock)->rlock){-.-.}: __lock_acquire+0x101f/0x12a0 lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 __queue_work+0xb2/0x520 queue_work_on+0x38/0x80 free_percpu+0x221/0x260 pcpu_freelist_destroy+0x11/0x20 stack_map_free+0x2a/0x40 bpf_map_free_deferred+0x3c/0x50 process_one_work+0x1f7/0x580 worker_thread+0x54/0x410 kthread+0x10f/0x150 ret_from_fork+0x24/0x30 other info that might help us debug this: Chain exists of: &(&pool->lock)->rlock --> &htab->buckets[i].lock --> pcpu_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(pcpu_lock); lock(&htab->buckets[i].lock); lock(pcpu_lock); lock(&(&pool->lock)->rlock); *** DEADLOCK *** 3 locks held by kworker/23:255/18872: #0: 00000000b36a6e16 ((wq_completion)events){+.+.}, at: process_one_work+0x17a/0x580 #1: 00000000dfd966f0 ((work_completion)(&map->work)){+.+.}, at: process_one_work+0x17a/0x580 #2: 00000000e3e7a6aa (pcpu_lock){..-.}, at: free_percpu+0x36/0x260 stack backtrace: CPU: 23 PID: 18872 Comm: kworker/23:255 Not tainted 5.1.0-dbg-DEV #1 Hardware name: ... Workqueue: events bpf_map_free_deferred Call Trace: dump_stack+0x67/0x95 print_circular_bug.isra.38+0x1c6/0x220 check_prev_add.constprop.50+0x9f6/0xd20 __lock_acquire+0x101f/0x12a0 lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 __queue_work+0xb2/0x520 queue_work_on+0x38/0x80 free_percpu+0x221/0x260 pcpu_freelist_destroy+0x11/0x20 stack_map_free+0x2a/0x40 bpf_map_free_deferred+0x3c/0x50 process_one_work+0x1f7/0x580 worker_thread+0x54/0x410 kthread+0x10f/0x150 ret_from_fork+0x24/0x30 Signed-off-by: John Sperbeck <jsperbeck@google.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-05-07 18:43:20 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: add tracepoint support for percpu memory Add support for tracepoints to the following events: chunk allocation, chunk free, area allocation, area free, and area allocation failure. This should let us replay percpu memory requests and evaluate corresponding decisions. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:32 -04:00

percpu: finer grained locking to break deadlock and allow atomic free Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>

2009-03-07 00:44:13 +09:00

percpu: remove spurious lock dependency between percpu and sched In free_percpu() we sometimes call pcpu_schedule_balance_work() to queue a work item (which does a wakeup) while holding pcpu_lock. This creates an unnecessary lock dependency between pcpu_lock and the scheduler's pi_lock. There are other places where we call pcpu_schedule_balance_work() without hold pcpu_lock, and this case doesn't need to be different. Moving the call outside the lock prevents the following lockdep splat when running tools/testing/selftests/bpf/{test_maps,test_progs} in sequence with lockdep enabled: ====================================================== WARNING: possible circular locking dependency detected 5.1.0-dbg-DEV #1 Not tainted ------------------------------------------------------ kworker/23:255/18872 is trying to acquire lock: 000000000bc79290 (&(&pool->lock)->rlock){-.-.}, at: __queue_work+0xb2/0x520 but task is already holding lock: 00000000e3e7a6aa (pcpu_lock){..-.}, at: free_percpu+0x36/0x260 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (pcpu_lock){..-.}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 pcpu_alloc+0xfa/0x780 __alloc_percpu_gfp+0x12/0x20 alloc_htab_elem+0x184/0x2b0 __htab_percpu_map_update_elem+0x252/0x290 bpf_percpu_hash_update+0x7c/0x130 __do_sys_bpf+0x1912/0x1be0 __x64_sys_bpf+0x1a/0x20 do_syscall_64+0x59/0x400 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&htab->buckets[i].lock){....}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 htab_map_update_elem+0x1af/0x3a0 -> #2 (&rq->lock){-.-.}: lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 task_fork_fair+0x37/0x160 sched_fork+0x211/0x310 copy_process.part.43+0x7b1/0x2160 _do_fork+0xda/0x6b0 kernel_thread+0x29/0x30 rest_init+0x22/0x260 arch_call_rest_init+0xe/0x10 start_kernel+0x4fd/0x520 x86_64_start_reservations+0x24/0x26 x86_64_start_kernel+0x6f/0x72 secondary_startup_64+0xa4/0xb0 -> #1 (&p->pi_lock){-.-.}: lock_acquire+0x9e/0x180 _raw_spin_lock_irqsave+0x3a/0x50 try_to_wake_up+0x41/0x600 wake_up_process+0x15/0x20 create_worker+0x16b/0x1e0 workqueue_init+0x279/0x2ee kernel_init_freeable+0xf7/0x288 kernel_init+0xf/0x180 ret_from_fork+0x24/0x30 -> #0 (&(&pool->lock)->rlock){-.-.}: __lock_acquire+0x101f/0x12a0 lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 __queue_work+0xb2/0x520 queue_work_on+0x38/0x80 free_percpu+0x221/0x260 pcpu_freelist_destroy+0x11/0x20 stack_map_free+0x2a/0x40 bpf_map_free_deferred+0x3c/0x50 process_one_work+0x1f7/0x580 worker_thread+0x54/0x410 kthread+0x10f/0x150 ret_from_fork+0x24/0x30 other info that might help us debug this: Chain exists of: &(&pool->lock)->rlock --> &htab->buckets[i].lock --> pcpu_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(pcpu_lock); lock(&htab->buckets[i].lock); lock(pcpu_lock); lock(&(&pool->lock)->rlock); *** DEADLOCK *** 3 locks held by kworker/23:255/18872: #0: 00000000b36a6e16 ((wq_completion)events){+.+.}, at: process_one_work+0x17a/0x580 #1: 00000000dfd966f0 ((work_completion)(&map->work)){+.+.}, at: process_one_work+0x17a/0x580 #2: 00000000e3e7a6aa (pcpu_lock){..-.}, at: free_percpu+0x36/0x260 stack backtrace: CPU: 23 PID: 18872 Comm: kworker/23:255 Not tainted 5.1.0-dbg-DEV #1 Hardware name: ... Workqueue: events bpf_map_free_deferred Call Trace: dump_stack+0x67/0x95 print_circular_bug.isra.38+0x1c6/0x220 check_prev_add.constprop.50+0x9f6/0xd20 __lock_acquire+0x101f/0x12a0 lock_acquire+0x9e/0x180 _raw_spin_lock+0x2f/0x40 __queue_work+0xb2/0x520 queue_work_on+0x38/0x80 free_percpu+0x221/0x260 pcpu_freelist_destroy+0x11/0x20 stack_map_free+0x2a/0x40 bpf_map_free_deferred+0x3c/0x50 process_one_work+0x1f7/0x580 worker_thread+0x54/0x410 kthread+0x10f/0x150 ret_from_fork+0x24/0x30 Signed-off-by: John Sperbeck <jsperbeck@google.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-05-07 18:43:20 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

locking/lockdep: Handle statically initialized PER_CPU locks properly If a PER_CPU struct which contains a spin_lock is statically initialized via: DEFINE_PER_CPU(struct foo, bla) = { .lock = __SPIN_LOCK_UNLOCKED(bla.lock) }; then lockdep assigns a seperate key to each lock because the logic for assigning a key to statically initialized locks is to use the address as the key. With per CPU locks the address is obvioulsy different on each CPU. That's wrong, because all locks should have the same key. To solve this the following modifications are required: 1) Extend the is_kernel/module_percpu_addr() functions to hand back the canonical address of the per CPU address, i.e. the per CPU address minus the per CPU offset. 2) Check the lock address with these functions and if the per CPU check matches use the returned canonical address as the lock key, so all per CPU locks have the same key. 3) Move the static_obj(key) check into look_up_lock_class() so this check can be avoided for statically initialized per CPU locks. That's required because the canonical address fails the static_obj(key) check for obvious reasons. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Merged Dan's fixups for !MODULES and !SMP into this patch. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Murphy <dmurphy@ti.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>

2017-02-27 15:37:36 +01:00

percpu, module: implement and use is_kernel/module_percpu_address() lockdep has custom code to check whether a pointer belongs to static percpu area which is somewhat broken. Implement proper is_kernel/module_percpu_address() and replace the custom code. On UP, percpu variables are regular static variables and can't be distinguished from them. Always return %false on UP. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@redhat.com>

2010-03-10 18:57:54 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu, module: implement and use is_kernel/module_percpu_address() lockdep has custom code to check whether a pointer belongs to static percpu area which is somewhat broken. Implement proper is_kernel/module_percpu_address() and replace the custom code. On UP, percpu variables are regular static variables and can't be distinguished from them. Always return %false on UP. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@redhat.com>

2010-03-10 18:57:54 +09:00

locking/lockdep: Handle statically initialized PER_CPU locks properly If a PER_CPU struct which contains a spin_lock is statically initialized via: DEFINE_PER_CPU(struct foo, bla) = { .lock = __SPIN_LOCK_UNLOCKED(bla.lock) }; then lockdep assigns a seperate key to each lock because the logic for assigning a key to statically initialized locks is to use the address as the key. With per CPU locks the address is obvioulsy different on each CPU. That's wrong, because all locks should have the same key. To solve this the following modifications are required: 1) Extend the is_kernel/module_percpu_addr() functions to hand back the canonical address of the per CPU address, i.e. the per CPU address minus the per CPU offset. 2) Check the lock address with these functions and if the per CPU check matches use the returned canonical address as the lock key, so all per CPU locks have the same key. 3) Move the static_obj(key) check into look_up_lock_class() so this check can be avoided for statically initialized per CPU locks. That's required because the canonical address fails the static_obj(key) check for obvious reasons. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Merged Dan's fixups for !MODULES and !SMP into this patch. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Murphy <dmurphy@ti.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>

2017-02-27 15:37:36 +01:00

percpu, module: implement and use is_kernel/module_percpu_address() lockdep has custom code to check whether a pointer belongs to static percpu area which is somewhat broken. Implement proper is_kernel/module_percpu_address() and replace the custom code. On UP, percpu variables are regular static variables and can't be distinguished from them. Always return %false on UP. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@redhat.com>

2010-03-10 18:57:54 +09:00

locking/lockdep: Handle statically initialized PER_CPU locks properly If a PER_CPU struct which contains a spin_lock is statically initialized via: DEFINE_PER_CPU(struct foo, bla) = { .lock = __SPIN_LOCK_UNLOCKED(bla.lock) }; then lockdep assigns a seperate key to each lock because the logic for assigning a key to statically initialized locks is to use the address as the key. With per CPU locks the address is obvioulsy different on each CPU. That's wrong, because all locks should have the same key. To solve this the following modifications are required: 1) Extend the is_kernel/module_percpu_addr() functions to hand back the canonical address of the per CPU address, i.e. the per CPU address minus the per CPU offset. 2) Check the lock address with these functions and if the per CPU check matches use the returned canonical address as the lock key, so all per CPU locks have the same key. 3) Move the static_obj(key) check into look_up_lock_class() so this check can be avoided for statically initialized per CPU locks. That's required because the canonical address fails the static_obj(key) check for obvious reasons. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Merged Dan's fixups for !MODULES and !SMP into this patch. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Murphy <dmurphy@ti.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>

2017-02-27 15:37:36 +01:00

lockdep: Fix per-cpu static objects Since commit 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly") we try to collapse per-cpu locks into a single class by giving them all the same key. For this key we choose the canonical address of the per-cpu object, which would be the offset into the per-cpu area. This has two problems: - there is a case where we run !0 lock->key through static_obj() and expect this to pass; it doesn't for canonical pointers. - 0 is a valid canonical address. Cure both issues by redefining the canonical address as the address of the per-cpu variable on the boot CPU. Since I didn't want to rely on CPU0 being the boot-cpu, or even existing at all, track the boot CPU in a variable. Fixes: 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly") Reported-by: kernel test robot <fengguang.wu@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Borislav Petkov <bp@suse.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: linux-mm@kvack.org Cc: wfg@linux.intel.com Cc: kernel test robot <fengguang.wu@intel.com> Cc: LKP <lkp@01.org> Link: http://lkml.kernel.org/r/20170320114108.kbvcsuepem45j5cr@hirez.programming.kicks-ass.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2017-03-20 12:26:55 +01:00

locking/lockdep: Handle statically initialized PER_CPU locks properly If a PER_CPU struct which contains a spin_lock is statically initialized via: DEFINE_PER_CPU(struct foo, bla) = { .lock = __SPIN_LOCK_UNLOCKED(bla.lock) }; then lockdep assigns a seperate key to each lock because the logic for assigning a key to statically initialized locks is to use the address as the key. With per CPU locks the address is obvioulsy different on each CPU. That's wrong, because all locks should have the same key. To solve this the following modifications are required: 1) Extend the is_kernel/module_percpu_addr() functions to hand back the canonical address of the per CPU address, i.e. the per CPU address minus the per CPU offset. 2) Check the lock address with these functions and if the per CPU check matches use the returned canonical address as the lock key, so all per CPU locks have the same key. 3) Move the static_obj(key) check into look_up_lock_class() so this check can be avoided for statically initialized per CPU locks. That's required because the canonical address fails the static_obj(key) check for obvious reasons. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Merged Dan's fixups for !MODULES and !SMP into this patch. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Murphy <dmurphy@ti.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>

2017-02-27 15:37:36 +01:00

lockdep: Fix per-cpu static objects Since commit 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly") we try to collapse per-cpu locks into a single class by giving them all the same key. For this key we choose the canonical address of the per-cpu object, which would be the offset into the per-cpu area. This has two problems: - there is a case where we run !0 lock->key through static_obj() and expect this to pass; it doesn't for canonical pointers. - 0 is a valid canonical address. Cure both issues by redefining the canonical address as the address of the per-cpu variable on the boot CPU. Since I didn't want to rely on CPU0 being the boot-cpu, or even existing at all, track the boot CPU in a variable. Fixes: 383776fa7527 ("locking/lockdep: Handle statically initialized PER_CPU locks properly") Reported-by: kernel test robot <fengguang.wu@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Borislav Petkov <bp@suse.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: linux-mm@kvack.org Cc: wfg@linux.intel.com Cc: kernel test robot <fengguang.wu@intel.com> Cc: LKP <lkp@01.org> Link: http://lkml.kernel.org/r/20170320114108.kbvcsuepem45j5cr@hirez.programming.kicks-ass.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2017-03-20 12:26:55 +01:00

percpu, module: implement and use is_kernel/module_percpu_address() lockdep has custom code to check whether a pointer belongs to static percpu area which is somewhat broken. Implement proper is_kernel/module_percpu_address() and replace the custom code. On UP, percpu variables are regular static variables and can't be distinguished from them. Always return %false on UP. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@redhat.com>

2010-03-10 18:57:54 +09:00

locking/lockdep: Handle statically initialized PER_CPU locks properly If a PER_CPU struct which contains a spin_lock is statically initialized via: DEFINE_PER_CPU(struct foo, bla) = { .lock = __SPIN_LOCK_UNLOCKED(bla.lock) }; then lockdep assigns a seperate key to each lock because the logic for assigning a key to statically initialized locks is to use the address as the key. With per CPU locks the address is obvioulsy different on each CPU. That's wrong, because all locks should have the same key. To solve this the following modifications are required: 1) Extend the is_kernel/module_percpu_addr() functions to hand back the canonical address of the per CPU address, i.e. the per CPU address minus the per CPU offset. 2) Check the lock address with these functions and if the per CPU check matches use the returned canonical address as the lock key, so all per CPU locks have the same key. 3) Move the static_obj(key) check into look_up_lock_class() so this check can be avoided for statically initialized per CPU locks. That's required because the canonical address fails the static_obj(key) check for obvious reasons. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Merged Dan's fixups for !MODULES and !SMP into this patch. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Murphy <dmurphy@ti.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>

2017-02-27 15:37:36 +01:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu, module: implement and use is_kernel/module_percpu_address() lockdep has custom code to check whether a pointer belongs to static percpu area which is somewhat broken. Implement proper is_kernel/module_percpu_address() and replace the custom code. On UP, percpu variables are regular static variables and can't be distinguished from them. Always return %false on UP. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@redhat.com>

2010-03-10 18:57:54 +09:00

locking/lockdep: Handle statically initialized PER_CPU locks properly If a PER_CPU struct which contains a spin_lock is statically initialized via: DEFINE_PER_CPU(struct foo, bla) = { .lock = __SPIN_LOCK_UNLOCKED(bla.lock) }; then lockdep assigns a seperate key to each lock because the logic for assigning a key to statically initialized locks is to use the address as the key. With per CPU locks the address is obvioulsy different on each CPU. That's wrong, because all locks should have the same key. To solve this the following modifications are required: 1) Extend the is_kernel/module_percpu_addr() functions to hand back the canonical address of the per CPU address, i.e. the per CPU address minus the per CPU offset. 2) Check the lock address with these functions and if the per CPU check matches use the returned canonical address as the lock key, so all per CPU locks have the same key. 3) Move the static_obj(key) check into look_up_lock_class() so this check can be avoided for statically initialized per CPU locks. That's required because the canonical address fails the static_obj(key) check for obvious reasons. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Merged Dan's fixups for !MODULES and !SMP into this patch. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Murphy <dmurphy@ti.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>

2017-02-27 15:37:36 +01:00

percpu: Fix kdump failure if booted with percpu_alloc=page o kdump functionality reserves a per cpu area at boot time and exports the physical address of that area to user space through sys interface. This area stores some dump related information like cpu register states etc at the time of crash. o We were assuming that per cpu area always come from linearly mapped meory region and using __pa() to determine physical address. With percpu_alloc=page, per cpu area can come from vmalloc region also and __pa() breaks. o This patch implments a new function to convert per cpu address to physical address. Before the patch, crash_notes addresses looked as follows. cpu0 60fffff49800 cpu1 60fffff60800 cpu2 60fffff77800 These are bogus phsyical addresses. After the patch, address are following. cpu0 13eb44000 cpu1 13eb43000 cpu2 13eb42000 cpu3 13eb41000 These look fine. I got 4G of memory and /proc/iomem tell me following. 100000000-13fffffff : System RAM tj: * added missing asm/io.h include reported by Stephen Rothwell * repositioned per_cpu_ptr_phys() in percpu.c and added comment. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au>

2009-11-24 15:50:03 +09:00

percpu: explain why per_cpu_ptr_to_phys() is more complicated than necessary Add comments about current per_cpu_ptr_to_phys implementation to explain why the logic is more complicated than necessary. -tj: relocated comment into kerneldoc comment Signed-off-by: Dave Young <dyoung@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2011-11-23 08:20:53 -08:00

percpu: Fix trivial typos in comments Change 'tranlated' to 'translated' Change 'mutliples' to 'multiples' Signed-off-by: Yannick Guerrini <yguerrini@tomshardware.fr> Signed-off-by: Tejun Heo <tj@kernel.org>

2015-03-06 23:30:42 +01:00

percpu: explain why per_cpu_ptr_to_phys() is more complicated than necessary Add comments about current per_cpu_ptr_to_phys implementation to explain why the logic is more complicated than necessary. -tj: relocated comment into kerneldoc comment Signed-off-by: Dave Young <dyoung@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2011-11-23 08:20:53 -08:00

percpu: Fix kdump failure if booted with percpu_alloc=page o kdump functionality reserves a per cpu area at boot time and exports the physical address of that area to user space through sys interface. This area stores some dump related information like cpu register states etc at the time of crash. o We were assuming that per cpu area always come from linearly mapped meory region and using __pa() to determine physical address. With percpu_alloc=page, per cpu area can come from vmalloc region also and __pa() breaks. o This patch implments a new function to convert per cpu address to physical address. Before the patch, crash_notes addresses looked as follows. cpu0 60fffff49800 cpu1 60fffff60800 cpu2 60fffff77800 These are bogus phsyical addresses. After the patch, address are following. cpu0 13eb44000 cpu1 13eb43000 cpu2 13eb42000 cpu3 13eb41000 These look fine. I got 4G of memory and /proc/iomem tell me following. 100000000-13fffffff : System RAM tj: * added missing asm/io.h include reported by Stephen Rothwell * repositioned per_cpu_ptr_phys() in percpu.c and added comment. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au>

2009-11-24 15:50:03 +09:00

percpu: fix first chunk match in per_cpu_ptr_to_phys() per_cpu_ptr_to_phys() determines whether the passed in @addr belongs to the first_chunk or not by just matching the address against the address range of the base unit (unit0, used by cpu0). When an adress from another cpu was passed in, it will always determine that the address doesn't belong to the first chunk even when it does. This makes the function return a bogus physical address which may lead to crash. This problem was discovered by Cliff Wickman while investigating a crash during kdump on a SGI UV system. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Cliff Wickman <cpw@sgi.com> Tested-by: Cliff Wickman <cpw@sgi.com> Cc: stable@kernel.org

2010-06-18 11:44:31 +02:00

percpu: fix chunk range calculation Percpu allocator recorded the cpus which map to the first and last units in pcpu_first/last_unit_cpu respectively and used them to determine the address range of a chunk - e.g. it assumed that the first unit has the lowest address in a chunk while the last unit has the highest address. This simply isn't true. Groups in a chunk can have arbitrary positive or negative offsets from the previous one and there is no guarantee that the first unit occupies the lowest offset while the last one the highest. Fix it by actually comparing unit offsets to determine cpus occupying the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu to pcpu_low/high_unit_cpu to avoid confusion. The chunk address range is used to flush cache on vmalloc area map/unmap and decide whether a given address is in the first chunk by per_cpu_ptr_to_phys() and the bug was discovered by invalid per_cpu_ptr_to_phys() translation for crash_note. Kudos to Dave Young for tracking down the problem. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: WANG Cong <xiyou.wangcong@gmail.com> Reported-by: Dave Young <dyoung@redhat.com> Tested-by: Dave Young <dyoung@redhat.com> LKML-Reference: <4EC21F67.10905@redhat.com> Cc: stable @kernel.org

2011-11-18 10:55:35 -08:00

percpu: fix first chunk match in per_cpu_ptr_to_phys() per_cpu_ptr_to_phys() determines whether the passed in @addr belongs to the first_chunk or not by just matching the address against the address range of the base unit (unit0, used by cpu0). When an adress from another cpu was passed in, it will always determine that the address doesn't belong to the first chunk even when it does. This makes the function return a bogus physical address which may lead to crash. This problem was discovered by Cliff Wickman while investigating a crash during kdump on a SGI UV system. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Cliff Wickman <cpw@sgi.com> Tested-by: Cliff Wickman <cpw@sgi.com> Cc: stable@kernel.org

2010-06-18 11:44:31 +02:00

percpu: fix chunk range calculation Percpu allocator recorded the cpus which map to the first and last units in pcpu_first/last_unit_cpu respectively and used them to determine the address range of a chunk - e.g. it assumed that the first unit has the lowest address in a chunk while the last unit has the highest address. This simply isn't true. Groups in a chunk can have arbitrary positive or negative offsets from the previous one and there is no guarantee that the first unit occupies the lowest offset while the last one the highest. Fix it by actually comparing unit offsets to determine cpus occupying the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu to pcpu_low/high_unit_cpu to avoid confusion. The chunk address range is used to flush cache on vmalloc area map/unmap and decide whether a given address is in the first chunk by per_cpu_ptr_to_phys() and the bug was discovered by invalid per_cpu_ptr_to_phys() translation for crash_note. Kudos to Dave Young for tracking down the problem. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: WANG Cong <xiyou.wangcong@gmail.com> Reported-by: Dave Young <dyoung@redhat.com> Tested-by: Dave Young <dyoung@redhat.com> LKML-Reference: <4EC21F67.10905@redhat.com> Cc: stable @kernel.org

2011-11-18 10:55:35 -08:00

percpu: fix first chunk match in per_cpu_ptr_to_phys() per_cpu_ptr_to_phys() determines whether the passed in @addr belongs to the first_chunk or not by just matching the address against the address range of the base unit (unit0, used by cpu0). When an adress from another cpu was passed in, it will always determine that the address doesn't belong to the first chunk even when it does. This makes the function return a bogus physical address which may lead to crash. This problem was discovered by Cliff Wickman while investigating a crash during kdump on a SGI UV system. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Cliff Wickman <cpw@sgi.com> Tested-by: Cliff Wickman <cpw@sgi.com> Cc: stable@kernel.org

2010-06-18 11:44:31 +02:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: fix first chunk match in per_cpu_ptr_to_phys() per_cpu_ptr_to_phys() determines whether the passed in @addr belongs to the first_chunk or not by just matching the address against the address range of the base unit (unit0, used by cpu0). When an adress from another cpu was passed in, it will always determine that the address doesn't belong to the first chunk even when it does. This makes the function return a bogus physical address which may lead to crash. This problem was discovered by Cliff Wickman while investigating a crash during kdump on a SGI UV system. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Cliff Wickman <cpw@sgi.com> Tested-by: Cliff Wickman <cpw@sgi.com> Cc: stable@kernel.org

2010-06-18 11:44:31 +02:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: fix chunk range calculation Percpu allocator recorded the cpus which map to the first and last units in pcpu_first/last_unit_cpu respectively and used them to determine the address range of a chunk - e.g. it assumed that the first unit has the lowest address in a chunk while the last unit has the highest address. This simply isn't true. Groups in a chunk can have arbitrary positive or negative offsets from the previous one and there is no guarantee that the first unit occupies the lowest offset while the last one the highest. Fix it by actually comparing unit offsets to determine cpus occupying the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu to pcpu_low/high_unit_cpu to avoid confusion. The chunk address range is used to flush cache on vmalloc area map/unmap and decide whether a given address is in the first chunk by per_cpu_ptr_to_phys() and the bug was discovered by invalid per_cpu_ptr_to_phys() translation for crash_note. Kudos to Dave Young for tracking down the problem. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: WANG Cong <xiyou.wangcong@gmail.com> Reported-by: Dave Young <dyoung@redhat.com> Tested-by: Dave Young <dyoung@redhat.com> LKML-Reference: <4EC21F67.10905@redhat.com> Cc: stable @kernel.org

2011-11-18 10:55:35 -08:00

percpu: fix first chunk match in per_cpu_ptr_to_phys() per_cpu_ptr_to_phys() determines whether the passed in @addr belongs to the first_chunk or not by just matching the address against the address range of the base unit (unit0, used by cpu0). When an adress from another cpu was passed in, it will always determine that the address doesn't belong to the first chunk even when it does. This makes the function return a bogus physical address which may lead to crash. This problem was discovered by Cliff Wickman while investigating a crash during kdump on a SGI UV system. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Cliff Wickman <cpw@sgi.com> Tested-by: Cliff Wickman <cpw@sgi.com> Cc: stable@kernel.org

2010-06-18 11:44:31 +02:00

NOMMU: percpu should use is_vmalloc_addr(). per_cpu_ptr_to_phys() uses VMALLOC_START and VMALLOC_END to determine if an address is in the vmalloc() region or not. This is incorrect on NOMMU as there is no real vmalloc() capability (vmalloc() is emulated by kmalloc()). The correct way to do this is to use is_vmalloc_addr(). This encapsulates the vmalloc() region test in MMU mode and just returns 0 in NOMMU mode. On FRV in NOMMU mode, the percpu compilation fails without this patch: mm/percpu.c: In function 'per_cpu_ptr_to_phys': mm/percpu.c:1011: error: 'VMALLOC_START' undeclared (first use in this function) mm/percpu.c:1011: error: (Each undeclared identifier is reported only once mm/percpu.c:1011: error: for each function it appears in.) mm/percpu.c:1012: error: 'VMALLOC_END' undeclared (first use in this function) mm/percpu.c:1018: warning: control reaches end of non-void function Signed-off-by: David Howells <dhowells@redhat.com>

2011-03-28 12:53:29 +01:00

percpu: factor out pcpu_addr_in_first/reserved_chunk() and update per_cpu_ptr_to_phys() Factor out pcpu_addr_in_first/reserved_chunk() from pcpu_chunk_addr_search() and use it to update per_cpu_ptr_to_phys() such that it handles first chunk differently from the rest. This patch doesn't cause any functional change and is to prepare for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:00 +09:00

percpu: fix per_cpu_ptr_to_phys() handling of non-page-aligned addresses per_cpu_ptr_to_phys() incorrectly rounds up its result for non-kmalloc case to the page boundary, which is bogus for any non-page-aligned address. This affects the only in-tree user of this function - sysfs handler for per-cpu 'crash_notes' physical address. The trouble is that the crash_notes per-cpu variable is not page-aligned: crash_notes = 0xc08e8ed4 PER-CPU OFFSET VALUES: CPU 0: 3711f000 CPU 1: 37129000 CPU 2: 37133000 CPU 3: 3713d000 So, the per-cpu addresses are: crash_notes on CPU 0: f7a07ed4 => phys 36b57ed4 crash_notes on CPU 1: f7a11ed4 => phys 36b4ded4 crash_notes on CPU 2: f7a1bed4 => phys 36b43ed4 crash_notes on CPU 3: f7a25ed4 => phys 36b39ed4 However, /sys/devices/system/cpu/cpu*/crash_notes says: /sys/devices/system/cpu/cpu0/crash_notes: 36b57000 /sys/devices/system/cpu/cpu1/crash_notes: 36b4d000 /sys/devices/system/cpu/cpu2/crash_notes: 36b43000 /sys/devices/system/cpu/cpu3/crash_notes: 36b39000 As you can see, all values are rounded down to a page boundary. Consequently, this is where kexec sets up the NOTE segments, and thus where the secondary kernel is looking for them. However, when the first kernel crashes, it saves the notes to the unaligned addresses, where they are not found. Fix it by adding offset_in_page() to the translated page address. -tj: Combined Eugene's and Petr's commit messages. Signed-off-by: Eugene Surovegin <ebs@ebshome.net> Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Petr Tesarik <ptesarik@suse.cz> Cc: stable@kernel.org

2011-12-15 11:25:59 -08:00

percpu: factor out pcpu_addr_in_first/reserved_chunk() and update per_cpu_ptr_to_phys() Factor out pcpu_addr_in_first/reserved_chunk() from pcpu_chunk_addr_search() and use it to update per_cpu_ptr_to_phys() such that it handles first chunk differently from the rest. This patch doesn't cause any functional change and is to prepare for percpu nommu support. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:00 +09:00

percpu: fix per_cpu_ptr_to_phys() handling of non-page-aligned addresses per_cpu_ptr_to_phys() incorrectly rounds up its result for non-kmalloc case to the page boundary, which is bogus for any non-page-aligned address. This affects the only in-tree user of this function - sysfs handler for per-cpu 'crash_notes' physical address. The trouble is that the crash_notes per-cpu variable is not page-aligned: crash_notes = 0xc08e8ed4 PER-CPU OFFSET VALUES: CPU 0: 3711f000 CPU 1: 37129000 CPU 2: 37133000 CPU 3: 3713d000 So, the per-cpu addresses are: crash_notes on CPU 0: f7a07ed4 => phys 36b57ed4 crash_notes on CPU 1: f7a11ed4 => phys 36b4ded4 crash_notes on CPU 2: f7a1bed4 => phys 36b43ed4 crash_notes on CPU 3: f7a25ed4 => phys 36b39ed4 However, /sys/devices/system/cpu/cpu*/crash_notes says: /sys/devices/system/cpu/cpu0/crash_notes: 36b57000 /sys/devices/system/cpu/cpu1/crash_notes: 36b4d000 /sys/devices/system/cpu/cpu2/crash_notes: 36b43000 /sys/devices/system/cpu/cpu3/crash_notes: 36b39000 As you can see, all values are rounded down to a page boundary. Consequently, this is where kexec sets up the NOTE segments, and thus where the secondary kernel is looking for them. However, when the first kernel crashes, it saves the notes to the unaligned addresses, where they are not found. Fix it by adding offset_in_page() to the translated page address. -tj: Combined Eugene's and Petr's commit messages. Signed-off-by: Eugene Surovegin <ebs@ebshome.net> Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Petr Tesarik <ptesarik@suse.cz> Cc: stable@kernel.org

2011-12-15 11:25:59 -08:00

percpu: Fix kdump failure if booted with percpu_alloc=page o kdump functionality reserves a per cpu area at boot time and exports the physical address of that area to user space through sys interface. This area stores some dump related information like cpu register states etc at the time of crash. o We were assuming that per cpu area always come from linearly mapped meory region and using __pa() to determine physical address. With percpu_alloc=page, per cpu area can come from vmalloc region also and __pa() breaks. o This patch implments a new function to convert per cpu address to physical address. Before the patch, crash_notes addresses looked as follows. cpu0 60fffff49800 cpu1 60fffff60800 cpu2 60fffff77800 These are bogus phsyical addresses. After the patch, address are following. cpu0 13eb44000 cpu1 13eb43000 cpu2 13eb42000 cpu3 13eb41000 These look fine. I got 4G of memory and /proc/iomem tell me following. 100000000-13fffffff : System RAM tj: * added missing asm/io.h include reported by Stephen Rothwell * repositioned per_cpu_ptr_phys() in percpu.c and added comment. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au>

2009-11-24 15:50:03 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: Use struct_size() helper One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct pcpu_alloc_info { ... struct pcpu_group_info groups[]; }; Make use of the struct_size() helper instead of an open-coded version in order to avoid any potential type mistakes. So, replace the following form: sizeof(*ai) + nr_groups * sizeof(ai->groups[0]) with: struct_size(ai, groups, nr_groups) This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-08-29 14:06:05 -05:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

memblock: drop memblock_alloc_*_nopanic() variants As all the memblock allocation functions return NULL in case of error rather than panic(), the duplicates with _nopanic suffix can be removed. Link: http://lkml.kernel.org/r/1548057848-15136-22-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Petr Mladek <pmladek@suse.com> [printk] Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:42 -07:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

memblock: use memblock_free for freeing virtual pointers Rename memblock_free_ptr() to memblock_free() and use memblock_free() when freeing a virtual pointer so that memblock_free() will be a counterpart of memblock_alloc() The callers are updated with the below semantic patch and manual addition of (void *) casting to pointers that are represented by unsigned long variables. @@ identifier vaddr; expression size; @@ ( - memblock_phys_free(__pa(vaddr), size); + memblock_free(vaddr, size); | - memblock_free_ptr(vaddr, size); + memblock_free(vaddr, size); ) [sfr@canb.auug.org.au: fixup] Link: https://lkml.kernel.org/r/20211018192940.3d1d532f@canb.auug.org.au Link: https://lkml.kernel.org/r/20210930185031.18648-7-rppt@kernel.org Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Juergen Gross <jgross@suse.com> Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2021-11-05 13:43:22 -07:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

mm: convert printk(KERN_<LEVEL> to pr_<level> Most of the mm subsystem uses pr_<level> so make it consistent. Miscellanea: - Realign arguments - Add missing newline to format - kmemleak-test.c has a "kmemleak: " prefix added to the "Kmemleak testing" logging message via pr_fmt Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> [percpu] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:50 -07:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

mm: convert printk(KERN_<LEVEL> to pr_<level> Most of the mm subsystem uses pr_<level> so make it consistent. Miscellanea: - Realign arguments - Add missing newline to format - kmemleak-test.c has a "kmemleak: " prefix added to the "Kmemleak testing" logging message via pr_fmt Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> [percpu] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:50 -07:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

mm: convert printk(KERN_<LEVEL> to pr_<level> Most of the mm subsystem uses pr_<level> so make it consistent. Miscellanea: - Realign arguments - Add missing newline to format - kmemleak-test.c has a "kmemleak: " prefix added to the "Kmemleak testing" logging message via pr_fmt Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> [percpu] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:50 -07:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

mm: convert printk(KERN_<LEVEL> to pr_<level> Most of the mm subsystem uses pr_<level> so make it consistent. Miscellanea: - Realign arguments - Add missing newline to format - kmemleak-test.c has a "kmemleak: " prefix added to the "Kmemleak testing" logging message via pr_fmt Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> [percpu] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:50 -07:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

mm: convert printk(KERN_<LEVEL> to pr_<level> Most of the mm subsystem uses pr_<level> so make it consistent. Miscellanea: - Realign arguments - Add missing newline to format - kmemleak-test.c has a "kmemleak: " prefix added to the "Kmemleak testing" logging message via pr_fmt Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> [percpu] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:50 -07:00

percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: simplify pcpu_setup_first_chunk() Now that all first chunk allocator helpers allocate and map the first chunk themselves, there's no need to have optional default alloc/map in pcpu_setup_first_chunk(). Drop @populate_pte_fn and only leave @dyn_size optional and make all other params mandatory. This makes it much easier to follow what pcpu_setup_first_chunk() is doing and what actual differences tweaking each parameter results in. [ Impact: drop unused code path ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: fix typo in pcpu_setup_first_chunk() comment s/perpcu/percpu/ Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: updated title]

2019-07-21 11:56:33 +02:00

percpu: simplify pcpu_setup_first_chunk() Now that all first chunk allocator helpers allocate and map the first chunk themselves, there's no need to have optional default alloc/map in pcpu_setup_first_chunk(). Drop @populate_pte_fn and only leave @dyn_size optional and make all other params mandatory. This makes it much easier to follow what pcpu_setup_first_chunk() is doing and what actual differences tweaking each parameter results in. [ Impact: drop unused code path ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: more flexibility for @dyn_size of pcpu_setup_first_chunk() Impact: cleanup, more flexibility for first chunk init Non-negative @dyn_size used to be allowed iff @unit_size wasn't auto. This restriction stemmed from implementation detail and made things a bit less intuitive. This patch allows @dyn_size to be specified regardless of @unit_size and swaps the positions of @dyn_size and @unit_size so that the parameter order makes more sense (static, reserved and dyn sizes followed by enclosing unit_size). While at it, add @unit_size >= PCPU_MIN_UNIT_SIZE sanity check. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: simplify pcpu_setup_first_chunk() Now that all first chunk allocator helpers allocate and map the first chunk themselves, there's no need to have optional default alloc/map in pcpu_setup_first_chunk(). Drop @populate_pte_fn and only leave @dyn_size optional and make all other params mandatory. This makes it much easier to follow what pcpu_setup_first_chunk() is doing and what actual differences tweaking each parameter results in. [ Impact: drop unused code path ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: Make pcpu_setup_first_chunk() void function pcpu_setup_first_chunk() will panic or BUG_ON if the are some error and doesn't return any error, hence it can be defined to return void. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: fixed kbuild warning for pcpu_page_first_chunk()]

2019-07-03 16:25:52 +08:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: setup_first_chunk remove dyn_size and consolidate logic There is logic for setting variables in the static chunk init code that could be consolidated with the dynamic chunk init code. This combines this logic to setup for combining the allocation paths. reserved_size is used as the conditional as a dynamic region will always exist. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:01 -04:00

percpu: increase minimum percpu allocation size and align first regions This patch increases the minimum allocation size of percpu memory to 4-bytes. This change will help minimize the metadata overhead associated with the bitmap allocator. The assumption is that most allocations will be of objects or structs greater than 2 bytes with integers or longs being used rather than shorts. The first chunk regions are now aligned with the minimum allocation size. The reserved region is expected to be set as a multiple of the minimum allocation size. The static region is aligned up and the delta is removed from the dynamic size. This works because the dynamic size is increased to be page aligned. If the static size is not minimum allocation size aligned, then there must be a gap that is added to the dynamic size. The dynamic size will never be smaller than the set value. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:09 -04:00

percpu: use group information to allocate vmap areas sparsely ai->groups[] contains which units need to be put consecutively and at what offset from the chunk base address. Compile this information into pcpu_group_offsets[] and pcpu_group_sizes[] in pcpu_setup_first_chunk() and use them to allocate sparse vm areas using pcpu_get_vm_areas(). This will be used to allow directly using sparse NUMA memories as percpu areas. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de>

2009-08-14 15:00:52 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: modify base_addr to be region specific Originally, the first chunk was served by one or two chunks, each given a region they are responsible for. Despite this, the arithmetic was based off of the true base_addr of the chunk making it be overly inclusive. This patch moves the base_addr of chunks that are responsible for the first chunk. The base_addr must remain page aligned to keep the address alignment correct, so it is the beginning of the region served page aligned down. start_offset holds where the region served begins from this new base_addr. The corresponding percpu address checks are modified to be more specific as a result. The first chunk considers only the dynamic region and both first chunk and reserved chunk checks ignore the static region. The static region addresses should never be passed into the allocator. There is no impact here besides distinguishing the first chunk and making the checks specific. The percpu pointer to physical address is left intact as addresses are not given out in the non-allocated portion of percpu memory. nr_pages is added to pcpu_chunk to keep track of the size of the entire region served containing both start_offset and end_offset. This variable will be used to manage the bitmap allocator. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:05 -04:00

mm/percpu: add checks for the return value of memblock_alloc*() Add panic() calls if memblock_alloc() returns NULL. The panic() format duplicates the one used by memblock itself and in order to avoid explosion with long parameters list replace open coded allocation size calculations with a local variable. Link: http://lkml.kernel.org/r/1548057848-15136-17-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:15 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

mm: percpu: use pr_fmt to prefix output Use the normal mechanism to make the logging output consistently "percpu:" instead of a mix of "PERCPU:" and "percpu:" Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:53 -07:00

percpu: use %*pb[l] to print bitmaps including cpumasks and nodemasks printk and friends can now format bitmaps using '%*pb[l]'. cpumask and nodemask also provide cpumask_pr_args() and nodemask_pr_args() respectively which can be used to generate the two printf arguments necessary to format the specified cpu/nodemask. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2015-02-13 14:37:34 -08:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

mm/percpu: use offset_in_page macro linux/mm.h provides offset_in_page() macro. Let's use already predefined macro instead of (addr & ~PAGE_MASK). Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2015-11-05 18:46:43 -08:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

mm/percpu: use offset_in_page macro linux/mm.h provides offset_in_page() macro. Let's use already predefined macro instead of (addr & ~PAGE_MASK). Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2015-11-05 18:46:43 -08:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

mm/percpu: use offset_in_page macro linux/mm.h provides offset_in_page() macro. Let's use already predefined macro instead of (addr & ~PAGE_MASK). Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2015-11-05 18:46:43 -08:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: allow limited allocation before slab is online This patch updates percpu allocator such that it can serve limited amount of allocation before slab comes online. This is primarily to allow slab to depend on working percpu allocator. Two parameters, PERCPU_DYNAMIC_EARLY_SIZE and SLOTS, determine how much memory space and allocation map slots are reserved. If this reserved area is exhausted, WARN_ON_ONCE() will trigger and allocation will fail till slab comes online. The following changes are made to implement early alloc. * pcpu_mem_alloc() now checks slab_is_available() * Chunks are allocated using pcpu_mem_alloc() * Init paths make sure ai->dyn_size is at least as large as PERCPU_DYNAMIC_EARLY_SIZE. * Initial alloc maps are allocated in __initdata and copied to kmalloc'd areas once slab is online. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux-foundation.org>

2010-06-27 18:50:00 +02:00

percpu: increase minimum percpu allocation size and align first regions This patch increases the minimum allocation size of percpu memory to 4-bytes. This change will help minimize the metadata overhead associated with the bitmap allocator. The assumption is that most allocations will be of objects or structs greater than 2 bytes with integers or longs being used rather than shorts. The first chunk regions are now aligned with the minimum allocation size. The reserved region is expected to be set as a multiple of the minimum allocation size. The static region is aligned up and the delta is removed from the dynamic size. This works because the dynamic size is increased to be page aligned. If the static size is not minimum allocation size aligned, then there must be a gap that is added to the dynamic size. The dynamic size will never be smaller than the set value. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:09 -04:00

percpu: introduce bitmap metadata blocks This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:12 -04:00

percpu: move vmalloc based chunk management into percpu-vm.c Separate out and move chunk management (creation/desctruction and [de]population) code into percpu-vm.c which is included by percpu.c and compiled together. The interface for chunk management is defined as follows. * pcpu_populate_chunk - populate the specified range of a chunk * pcpu_depopulate_chunk - depopulate the specified range of a chunk * pcpu_create_chunk - create a new chunk * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop * pcpu_addr_to_page - translate address to physical address * pcpu_verify_alloc_info - check alloc_info is acceptable during init Other than wrapping vmalloc_to_page() inside pcpu_addr_to_page() and dummy pcpu_verify_alloc_info() implementation, this patch only moves code around. This separation is to allow alternate chunk management implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Graff Yang <graff.yang@gmail.com> Cc: Sonic Zhang <sonic.adi@gmail.com>

2010-04-09 18:57:01 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: use group information to allocate vmap areas sparsely ai->groups[] contains which units need to be put consecutively and at what offset from the chunk base address. Compile this information into pcpu_group_offsets[] and pcpu_group_sizes[] in pcpu_setup_first_chunk() and use them to allocate sparse vm areas using pcpu_get_vm_areas(). This will be used to allow directly using sparse NUMA memories as percpu areas. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de>

2009-08-14 15:00:52 +09:00

mm/percpu: add checks for the return value of memblock_alloc*() Add panic() calls if memblock_alloc() returns NULL. The panic() format duplicates the one used by memblock itself and in order to avoid explosion with long parameters list replace open coded allocation size calculations with a local variable. Link: http://lkml.kernel.org/r/1548057848-15136-17-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:15 -07:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: fix unit_map[] verification in pcpu_setup_first_chunk() pcpu_setup_first_chunk() incorrectly used NR_CPUS as the impossible unit number while unit number can equal and go over NR_CPUS with sparse unit map. This triggers BUG_ON() spuriously on machines which have non-power-of-two number of cpus. Use UINT_MAX instead. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Tony Vroon <tony@linx.net>

2009-09-29 09:17:56 +09:00

percpu: fix chunk range calculation Percpu allocator recorded the cpus which map to the first and last units in pcpu_first/last_unit_cpu respectively and used them to determine the address range of a chunk - e.g. it assumed that the first unit has the lowest address in a chunk while the last unit has the highest address. This simply isn't true. Groups in a chunk can have arbitrary positive or negative offsets from the previous one and there is no guarantee that the first unit occupies the lowest offset while the last one the highest. Fix it by actually comparing unit offsets to determine cpus occupying the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu to pcpu_low/high_unit_cpu to avoid confusion. The chunk address range is used to flush cache on vmalloc area map/unmap and decide whether a given address is in the first chunk by per_cpu_ptr_to_phys() and the bug was discovered by invalid per_cpu_ptr_to_phys() translation for crash_note. Kudos to Dave Young for tracking down the problem. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: WANG Cong <xiyou.wangcong@gmail.com> Reported-by: Dave Young <dyoung@redhat.com> Tested-by: Dave Young <dyoung@redhat.com> LKML-Reference: <4EC21F67.10905@redhat.com> Cc: stable @kernel.org

2011-11-18 10:55:35 -08:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: use group information to allocate vmap areas sparsely ai->groups[] contains which units need to be put consecutively and at what offset from the chunk base address. Compile this information into pcpu_group_offsets[] and pcpu_group_sizes[] in pcpu_setup_first_chunk() and use them to allocate sparse vm areas using pcpu_get_vm_areas(). This will be used to allow directly using sparse NUMA memories as percpu areas. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de>

2009-08-14 15:00:52 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: give more latitude to arch specific first chunk initialization Impact: more latitude for first percpu chunk allocation The first percpu chunk serves the kernel static percpu area and may or may not contain extra room for further dynamic allocation. Initialization of the first chunk needs to be done before normal memory allocation service is up, so it has its own init path - pcpu_setup_static(). It seems archs need more latitude while initializing the first chunk for example to take advantage of large page mapping. This patch makes the following changes to allow this. * Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space to reserve in the first chunk for further dynamic allocation. * Rename pcpu_setup_static() to pcpu_setup_first_chunk(). * Make pcpu_setup_first_chunk() much more flexible by fetching page pointer by callback and adding optional @unit_size, @free_size and @base_addr arguments which allow archs to selectively part of chunk initialization to their likings. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: off by one in BUG_ON() The unit_map[] array has "nr_cpu_ids" number of elements. It's allocated a few lines earlier in the function. So this test should be >= instead of >. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2014-10-29 11:45:04 +03:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: fix chunk range calculation Percpu allocator recorded the cpus which map to the first and last units in pcpu_first/last_unit_cpu respectively and used them to determine the address range of a chunk - e.g. it assumed that the first unit has the lowest address in a chunk while the last unit has the highest address. This simply isn't true. Groups in a chunk can have arbitrary positive or negative offsets from the previous one and there is no guarantee that the first unit occupies the lowest offset while the last one the highest. Fix it by actually comparing unit offsets to determine cpus occupying the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu to pcpu_low/high_unit_cpu to avoid confusion. The chunk address range is used to flush cache on vmalloc area map/unmap and decide whether a given address is in the first chunk by per_cpu_ptr_to_phys() and the bug was discovered by invalid per_cpu_ptr_to_phys() translation for crash_note. Kudos to Dave Young for tracking down the problem. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: WANG Cong <xiyou.wangcong@gmail.com> Reported-by: Dave Young <dyoung@redhat.com> Tested-by: Dave Young <dyoung@redhat.com> LKML-Reference: <4EC21F67.10905@redhat.com> Cc: stable @kernel.org

2011-11-18 10:55:35 -08:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: make pcpu_setup_first_chunk() failures more verbose The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 09:43:11 +09:00

percpu: print out alloc information with KERN_DEBUG instead of KERN_INFO Now that percpu allocator is mostly stable, there is no reason to print alloc information with KERN_INFO and clutter the boot messages. Switch it to KERN_DEBUG. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Mike Travis <travis@sgi.com>

2010-12-22 14:19:14 +01:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: use group information to allocate vmap areas sparsely ai->groups[] contains which units need to be put consecutively and at what offset from the chunk base address. Compile this information into pcpu_group_offsets[] and pcpu_group_sizes[] in pcpu_setup_first_chunk() and use them to allocate sparse vm areas using pcpu_get_vm_areas(). This will be used to allow directly using sparse NUMA memories as percpu areas. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de>

2009-08-14 15:00:52 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: allow non-linear / sparse cpu -> unit mapping Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: remove unit_size power-of-2 restriction Impact: allow unit_size to be arbitrary multiple of PAGE_SIZE In dynamic percpu allocator, there is no reason the unit size should be power of two. Remove the restriction. As non-power-of-two unit size means that empty chunks fall into the same slot index as lightly occupied chunks which is bad for reclaming. Reserve an extra slot for empty chunks. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: use group information to allocate vmap areas sparsely ai->groups[] contains which units need to be put consecutively and at what offset from the chunk base address. Compile this information into pcpu_group_offsets[] and pcpu_group_sizes[] in pcpu_setup_first_chunk() and use them to allocate sparse vm areas using pcpu_get_vm_areas(). This will be used to allow directly using sparse NUMA memories as percpu areas. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de>

2009-08-14 15:00:52 +09:00

mm/percpu.c: optimize the code in pcpu_setup_first_chunk() a little bit This removes the need of local varibale 'chunk', and optimize the code calling pcpu_alloc_first_chunk() to initialize reserved chunk and dynamic chunk to make it simpler. Signed-off-by: Baoquan He <bhe@redhat.com> [Dennis: reworded first chunk init comment] Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-22 09:14:37 +08:00

percpu: convert flexible array initializers to use struct_size() Use the safer macro as sparked by the long discussion in [1]. [1] https://lore.kernel.org/lkml/20200917204514.GA2880159@google.com/ Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2020-10-30 20:40:21 +00:00

percpu: use negative for auto for pcpu_setup_first_chunk() arguments Impact: argument semantic cleanup In pcpu_setup_first_chunk(), zero @unit_size and @dyn_size meant auto-sizing. It's okay for @unit_size as 0 doesn't make sense but 0 dynamic reserve size is valid. Alos, if arch @dyn_size is calculated from other parameters, it might end up passing in 0 @dyn_size and malfunction when the size is automatically adjusted. This patch makes both @unit_size and @dyn_size ssize_t and use -1 for auto sizing. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: expose statistics about percpu memory via debugfs There is limited visibility into the use of percpu memory leaving us unable to reason about correctness of parameters and overall use of percpu memory. These counters and statistics aim to help understand basic statistics about percpu memory such as number of allocations over the lifetime, allocation sizes, and fragmentation. New Config: PERCPU_STATS Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:31 -04:00

percpu: remove unit_size power-of-2 restriction Impact: allow unit_size to be arbitrary multiple of PAGE_SIZE In dynamic percpu allocator, there is no reason the unit size should be power of two. Remove the restriction. As non-power-of-two unit size means that empty chunks fall into the same slot index as lightly occupied chunks which is bad for reclaming. Reserve an extra slot for empty chunks. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

percpu: remove unit_size power-of-2 restriction Impact: allow unit_size to be arbitrary multiple of PAGE_SIZE In dynamic percpu allocator, there is no reason the unit size should be power of two. Remove the restriction. As non-power-of-two unit size means that empty chunks fall into the same slot index as lightly occupied chunks which is bad for reclaming. Reserve an extra slot for empty chunks. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-02-24 11:57:21 +09:00

percpu: implement partial chunk depopulation From Roman ("percpu: partial chunk depopulation"): In our [Facebook] production experience the percpu memory allocator is sometimes struggling with returning the memory to the system. A typical example is a creation of several thousands memory cgroups (each has several chunks of the percpu data used for vmstats, vmevents, ref counters etc). Deletion and complete releasing of these cgroups doesn't always lead to a shrinkage of the percpu memory, so that sometimes there are several GB's of memory wasted. The underlying problem is the fragmentation: to release an underlying chunk all percpu allocations should be released first. The percpu allocator tends to top up chunks to improve the utilization. It means new small-ish allocations (e.g. percpu ref counters) are placed onto almost filled old-ish chunks, effectively pinning them in memory. This patchset solves this problem by implementing a partial depopulation of percpu chunks: chunks with many empty pages are being asynchronously depopulated and the pages are returned to the system. To illustrate the problem the following script can be used: -- cd /sys/fs/cgroup mkdir percpu_test echo "+memory" > percpu_test/cgroup.subtree_control cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do mkdir percpu_test/cg_"${i}" for j in `seq 1 10`; do mkdir percpu_test/cg_"${i}"_"${j}" done done cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do for j in `seq 1 10`; do rmdir percpu_test/cg_"${i}"_"${j}" done done sleep 10 cat /proc/meminfo | grep Percpu for i in `seq 1 1000`; do rmdir percpu_test/cg_"${i}" done rmdir percpu_test -- It creates 11000 memory cgroups and removes every 10 out of 11. It prints the initial size of the percpu memory, the size after creating all cgroups and the size after deleting most of them. Results: vanilla: ./percpu_test.sh Percpu: 7488 kB Percpu: 481152 kB Percpu: 481152 kB with this patchset applied: ./percpu_test.sh Percpu: 7488 kB Percpu: 481408 kB Percpu: 135552 kB The total size of the percpu memory was reduced by more than 3.5 times. This patch: This patch implements partial depopulation of percpu chunks. As of now, a chunk can be depopulated only as a part of the final destruction, if there are no more outstanding allocations. However to minimize a memory waste it might be useful to depopulate a partially filed chunk, if a small number of outstanding allocations prevents the chunk from being fully reclaimed. This patch implements the following depopulation process: it scans over the chunk pages, looks for a range of empty and populated pages and performs the depopulation. To avoid races with new allocations, the chunk is previously isolated. After the depopulation the chunk is sidelined to a special list or freed. New allocations prefer using active chunks to sidelined chunks. If a sidelined chunk is used, it is reintegrated to the active lists. The depopulation is scheduled on the free path if the chunk is all of the following: 1) has more than 1/4 of total pages free and populated 2) the system has enough free percpu pages aside of this chunk 3) isn't the reserved chunk 4) isn't the first chunk If it's already depopulated but got free populated pages, it's a good target too. The chunk is moved to a special slot, pcpu_to_depopulate_slot, chunk->isolated is set, and the balance work item is scheduled. On isolation, these pages are removed from the pcpu_nr_empty_pop_pages. It is constantly replaced to the to_depopulate_slot when it meets these qualifications. pcpu_reclaim_populated() iterates over the to_depopulate_slot until it becomes empty. The depopulation is performed in the reverse direction to keep populated pages close to the beginning. Depopulated chunks are sidelined to preferentially avoid them for new allocations. When no active chunk can suffice a new allocation, sidelined chunks are first checked before creating a new chunk. Signed-off-by: Roman Gushchin <guro@fb.com> Co-developed-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Pratik Sampat <psampat@linux.ibm.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-04-07 20:57:36 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

mm/percpu: add checks for the return value of memblock_alloc*() Add panic() calls if memblock_alloc() returns NULL. The panic() format duplicates the one used by memblock itself and in order to avoid explosion with long parameters list replace open coded allocation size calculations with a local variable. Link: http://lkml.kernel.org/r/1548057848-15136-17-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:15 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

mm: memcg/percpu: account percpu memory to memory cgroups Percpu memory is becoming more and more widely used by various subsystems, and the total amount of memory controlled by the percpu allocator can make a good part of the total memory. As an example, bpf maps can consume a lot of percpu memory, and they are created by a user. Also, some cgroup internals (e.g. memory controller statistics) can be quite large. On a machine with many CPUs and big number of cgroups they can consume hundreds of megabytes. So the lack of memcg accounting is creating a breach in the memory isolation. Similar to the slab memory, percpu memory should be accounted by default. To implement the perpcu accounting it's possible to take the slab memory accounting as a model to follow. Let's introduce two types of percpu chunks: root and memcg. What makes memcg chunks different is an additional space allocated to store memcg membership information. If __GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used. If it's possible to charge the corresponding size to the target memory cgroup, allocation is performed, and the memcg ownership data is recorded. System-wide allocations are performed using root chunks, so there is no additional memory overhead. To implement a fast reparenting of percpu memory on memcg removal, we don't store mem_cgroup pointers directly: instead we use obj_cgroup API, introduced for slab accounting. [akpm@linux-foundation.org: fix CONFIG_MEMCG_KMEM=n build errors and warning] [akpm@linux-foundation.org: move unreachable code, per Roman] [cuibixuan@huawei.com: mm/percpu: fix 'defined but not used' warning] Link: http://lkml.kernel.org/r/6d41b939-a741-b521-a7a2-e7296ec16219@huawei.com Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Bixuan Cui <cuibixuan@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Bixuan Cui <cuibixuan@huawei.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/20200623184515.4132564-3-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2020-08-11 18:30:17 -07:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: increase minimum percpu allocation size and align first regions This patch increases the minimum allocation size of percpu memory to 4-bytes. This change will help minimize the metadata overhead associated with the bitmap allocator. The assumption is that most allocations will be of objects or structs greater than 2 bytes with integers or longs being used rather than shorts. The first chunk regions are now aligned with the minimum allocation size. The reserved region is expected to be set as a multiple of the minimum allocation size. The static region is aligned up and the delta is removed from the dynamic size. This works because the dynamic size is increased to be page aligned. If the static size is not minimum allocation size aligned, then there must be a gap that is added to the dynamic size. The dynamic size will never be smaller than the set value. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:09 -04:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

mm/percpu.c: optimize the code in pcpu_setup_first_chunk() a little bit This removes the need of local varibale 'chunk', and optimize the code calling pcpu_alloc_first_chunk() to initialize reserved chunk and dynamic chunk to make it simpler. Signed-off-by: Baoquan He <bhe@redhat.com> [Dennis: reworded first chunk init comment] Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-22 09:14:37 +08:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: increase minimum percpu allocation size and align first regions This patch increases the minimum allocation size of percpu memory to 4-bytes. This change will help minimize the metadata overhead associated with the bitmap allocator. The assumption is that most allocations will be of objects or structs greater than 2 bytes with integers or longs being used rather than shorts. The first chunk regions are now aligned with the minimum allocation size. The reserved region is expected to be set as a multiple of the minimum allocation size. The static region is aligned up and the delta is removed from the dynamic size. This works because the dynamic size is increased to be page aligned. If the static size is not minimum allocation size aligned, then there must be a gap that is added to the dynamic size. The dynamic size will never be smaller than the set value. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-24 19:02:09 -04:00

mm/percpu.c: optimize the code in pcpu_setup_first_chunk() a little bit This removes the need of local varibale 'chunk', and optimize the code calling pcpu_alloc_first_chunk() to initialize reserved chunk and dynamic chunk to make it simpler. Signed-off-by: Baoquan He <bhe@redhat.com> [Dennis: reworded first chunk init comment] Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-22 09:14:37 +08:00

percpu, module: implement reserved allocation and use it for module percpu variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-06 14:33:59 +09:00

percpu: rework memcg accounting The current implementation of the memcg accounting of the percpu memory is based on the idea of having two separate sets of chunks for accounted and non-accounted memory. This approach has an advantage of not wasting any extra memory for memcg data for non-accounted chunks, however it complicates the code and leads to a higher chunks number due to a lower chunk utilization. Instead of having two chunk types it's possible to declare all* chunks memcg-aware unless the kernel memory accounting is disabled globally by a boot option. The size of objcg_array is usually small in comparison to chunks themselves (it obviously depends on the number of CPUs), so even if some chunk will have no accounted allocations, the memory waste isn't significant and will likely be compensated by a higher chunk utilization. Also, with time more and more percpu allocations will likely become accounted. * The first chunk is initialized before the memory cgroup subsystem, so we don't know for sure whether we need to allocate obj_cgroups. Because it's small, let's make it free for use. Then we don't need to allocate obj_cgroups for it. Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-02 18:09:31 -07:00

percpu: don't put the first chunk in reverse-map rbtree Impact: both first chunks don't use rbtree, no functional change There can be two first chunks - reserved and dynamic with the former one being optional. Dynamic first chunk was linked on reverse-mapping rbtree while the reserved one was mapped manually using the start address and reserved offset limit. This patch makes both first chunks to be looked up manually without using the rbtree. This is to help getting rid of the rbtree. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: rusty@rustcorp.com.au Cc: Paul Mundt <lethal@linux-sh.org> Cc: rmk@arm.linux.org.uk Cc: starvik@axis.com Cc: ralf@linux-mips.org Cc: davem@davemloft.net Cc: cooloney@kernel.org Cc: kyle@mcmartin.ca Cc: matthew@wil.cx Cc: grundler@parisc-linux.org Cc: takata@linux-m32r.org Cc: benh@kernel.crashing.org Cc: rth@twiddle.net Cc: ink@jurassic.park.msu.ru Cc: heiko.carstens@de.ibm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> Cc: Christoph Lameter <cl@linux.com> LKML-Reference: <49D43CEA.3040609@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>

2009-04-02 13:19:54 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

/proc/meminfo: add percpu populated pages count Currently, percpu memory only exposes allocation and utilization information via debugfs. This more or less is only really useful for understanding the fragmentation and allocation information at a per-chunk level with a few global counters. This is also gated behind a config. BPF and cgroup, for example, have seen an increase in use causing increased use of percpu memory. Let's make it easier for someone to identify how much memory is being used. This patch adds the "Percpu" stat to meminfo to more easily look up how much percpu memory is in use. This number includes the cost for all allocated backing pages and not just insight at the per a unit, per chunk level. Metadata is excluded. I think excluding metadata is fair because the backing memory scales with the numbere of cpus and can quickly outweigh the metadata. It also makes this calculation light. Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2018-08-21 21:53:58 -07:00

percpu: expose statistics about percpu memory via debugfs There is limited visibility into the use of percpu memory leaving us unable to reason about correctness of parameters and overall use of percpu memory. These counters and statistics aim to help understand basic statistics about percpu memory such as number of allocations over the lifetime, allocation sizes, and fragmentation. New Config: PERCPU_STATS Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:31 -04:00

percpu: add tracepoint support for percpu memory Add support for tracepoints to the following events: chunk allocation, chunk free, area allocation, area free, and area allocation failure. This should let us replay percpu memory requests and evaluate corresponding decisions. Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:32 -04:00

percpu: expose statistics about percpu memory via debugfs There is limited visibility into the use of percpu memory leaving us unable to reason about correctness of parameters and overall use of percpu memory. These counters and statistics aim to help understand basic statistics about percpu memory such as number of allocations over the lifetime, allocation sizes, and fragmentation. New Config: PERCPU_STATS Signed-off-by: Dennis Zhou <dennisz@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-06-19 19:28:31 -04:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: add chunk->base_addr The only thing percpu allocator wants to know about a vmalloc area is the base address. Instead of requiring chunk->vm, add chunk->base_addr which contains the necessary value. This simplifies the code a bit and makes the dummy first_vm unnecessary. This change will ease allowing a chunk to be mapped by multiple vms. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:51 +09:00

percpu: implement new dynamic percpu allocator Impact: new scalable dynamic percpu allocator which allows dynamic percpu areas to be accessed the same way as static ones Implement scalable dynamic percpu allocator which can be used for both static and dynamic percpu areas. This will allow static and dynamic areas to share faster direct access methods. This feature is optional and enabled only when CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is defined by arch. Please read comment on top of mm/percpu.c for details. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org>

2009-02-20 16:29:08 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

sections: fix section conflicts in mm/percpu.c Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2012-10-04 17:12:07 -07:00

percpu: generalize first chunk allocator selection Now that all first chunk allocators are in mm/percpu.c, it makes sense to make generalize percpu_alloc kernel parameter. Define PCPU_FC_* and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code can use the set value to determine which first chunk allocator to use. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:50 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: generalize first chunk allocator selection Now that all first chunk allocators are in mm/percpu.c, it makes sense to make generalize percpu_alloc kernel parameter. Define PCPU_FC_* and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code can use the set value to determine which first chunk allocator to use. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:50 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: generalize first chunk allocator selection Now that all first chunk allocators are in mm/percpu.c, it makes sense to make generalize percpu_alloc kernel parameter. Define PCPU_FC_* and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code can use the set value to determine which first chunk allocator to use. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:50 +09:00

mm, percpu: Make sure percpu_alloc early parameter has an argument Otherwise we are getting a nil dereference if percpu_alloc kernel boot argument is specified without value. | [ 0.000000] BUG: unable to handle kernel NULL pointer dereference at (null) | [ 0.000000] IP: [<ffffffff81391360>] strcmp+0x10/0x30 Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Tejun Heo <tj@kernel.org>

2012-11-25 01:17:13 +04:00

percpu: generalize first chunk allocator selection Now that all first chunk allocators are in mm/percpu.c, it makes sense to make generalize percpu_alloc kernel parameter. Define PCPU_FC_* and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code can use the set value to determine which first chunk allocator to use. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:50 +09:00

mm: percpu: use pr_fmt to prefix output Use the normal mechanism to make the logging output consistently "percpu:" instead of a mix of "PERCPU:" and "percpu:" Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:53 -07:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: generalize first chunk allocator selection Now that all first chunk allocators are in mm/percpu.c, it makes sense to make generalize percpu_alloc kernel parameter. Define PCPU_FC_* and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code can use the set value to determine which first chunk allocator to use. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:50 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: generalize first chunk allocator selection Now that all first chunk allocators are in mm/percpu.c, it makes sense to make generalize percpu_alloc kernel parameter. Define PCPU_FC_* and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code can use the set value to determine which first chunk allocator to use. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:50 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: build first chunk allocators selectively There's no need to build unused first chunk allocators in. Define CONFIG_NEED_PER_CPU_*_FIRST_CHUNK and let archs enable them selectively. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:49 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: Fix trivial typos in comments Change 'tranlated' to 'translated' Change 'mutliples' to 'multiples' Signed-off-by: Yannick Guerrini <yguerrini@tomshardware.fr> Signed-off-by: Tejun Heo <tj@kernel.org>

2015-03-06 23:30:42 +01:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: fix clang modpost section mismatch pcpu_build_alloc_info() is an __init function that makes a call to cpumask_clear_cpu(). With CONFIG_GCOV_PROFILE_ALL enabled, the inline heuristics are modified and such cpumask_clear_cpu() which is marked inline doesn't get inlined. Because it works on mask in __initdata, modpost throws a section mismatch error. Arnd sent a patch with the flatten attribute as an alternative [2]. I've added it to compiler_attributes.h. modpost complaint: WARNING: modpost: vmlinux.o(.text+0x735425): Section mismatch in reference from the function cpumask_clear_cpu() to the variable .init.data:pcpu_build_alloc_info.mask The function cpumask_clear_cpu() references the variable __initdata pcpu_build_alloc_info.mask. This is often because cpumask_clear_cpu lacks a __initdata annotation or the annotation of pcpu_build_alloc_info.mask is wrong. clang output: mm/percpu.c:2724:5: remark: cpumask_clear_cpu not inlined into pcpu_build_alloc_info because too costly to inline (cost=725, threshold=325) [-Rpass-missed=inline] [1] https://lore.kernel.org/linux-mm/202012220454.9F6Bkz9q-lkp@intel.com/ [2] https://lore.kernel.org/lkml/CAK8P3a2ZWfNeXKSm8K_SUhhwkor17jFo3xApLXjzfPqX0eUDUA@mail.gmail.com/ Reported-by: kernel test robot <lkp@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-02-14 17:16:33 +00:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: reduce the number of cpu distance comparisons To build group_map[] and group_cnt[], we find out which group CPUs belong to by comparing the distance of the cpu. However, this includes cases where comparisons are not required. This patch uses a bitmap to record CPUs that is not classified in the group. CPUs that we know which group they belong to should be cleared from the bitmap. In result, we can reduce the number of unnecessary comparisons. Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: added cpumask_clear() call and #include cpumask.h.]

2020-10-30 10:38:20 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

treewide: Remove uninitialized_var() usage Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var$([^$]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by: Kees Cook <keescook@chromium.org>

2020-06-03 13:09:38 -07:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: reduce the number of cpu distance comparisons To build group_map[] and group_cnt[], we find out which group CPUs belong to by comparing the distance of the cpu. However, this includes cases where comparisons are not required. This patch uses a bitmap to record CPUs that is not classified in the group. CPUs that we know which group they belong to should be cleared from the bitmap. In result, we can reduce the number of unnecessary comparisons. Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: added cpumask_clear() call and #include cpumask.h.]

2020-10-30 10:38:20 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

Fix common misspellings Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

2011-03-30 22:57:33 -03:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: update the header comment and pcpu_build_alloc_info comments The header comment for percpu memory is a little hard to parse and is not super clear about how the first chunk is managed. This adds a little more clarity to the situation. There is also quite a bit of tricky logic in the pcpu_build_alloc_info. This adds a restructure of a comment to add a little more information. Unfortunately, you will still have to piece together a handful of other comments too, but should help direct you to the meaningful comments. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-15 22:23:09 -04:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

mm/percpu: use offset_in_page macro linux/mm.h provides offset_in_page() macro. Let's use already predefined macro instead of (addr & ~PAGE_MASK). Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2015-11-05 18:46:43 -08:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: reduce the number of cpu distance comparisons To build group_map[] and group_cnt[], we find out which group CPUs belong to by comparing the distance of the cpu. However, this includes cases where comparisons are not required. This patch uses a bitmap to record CPUs that is not classified in the group. CPUs that we know which group they belong to should be cleared from the bitmap. In result, we can reduce the number of unnecessary comparisons. Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: added cpumask_clear() call and #include cpumask.h.]

2020-10-30 10:38:20 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: reduce the number of cpu distance comparisons To build group_map[] and group_cnt[], we find out which group CPUs belong to by comparing the distance of the cpu. However, this includes cases where comparisons are not required. This patch uses a bitmap to record CPUs that is not classified in the group. CPUs that we know which group they belong to should be cleared from the bitmap. In result, we can reduce the number of unnecessary comparisons. Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: added cpumask_clear() call and #include cpumask.h.]

2020-10-30 10:38:20 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: reduce the number of cpu distance comparisons To build group_map[] and group_cnt[], we find out which group CPUs belong to by comparing the distance of the cpu. However, this includes cases where comparisons are not required. This patch uses a bitmap to record CPUs that is not classified in the group. CPUs that we know which group they belong to should be cleared from the bitmap. In result, we can reduce the number of unnecessary comparisons. Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: added cpumask_clear() call and #include cpumask.h.]

2020-10-30 10:38:20 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: reduce the number of cpu distance comparisons To build group_map[] and group_cnt[], we find out which group CPUs belong to by comparing the distance of the cpu. However, this includes cases where comparisons are not required. This patch uses a bitmap to record CPUs that is not classified in the group. CPUs that we know which group they belong to should be cleared from the bitmap. In result, we can reduce the number of unnecessary comparisons. Signed-off-by: Wonhyuk Yang <vvghjk1234@gmail.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: added cpumask_clear() call and #include cpumask.h.]

2020-10-30 10:38:20 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: update the header comment and pcpu_build_alloc_info comments The header comment for percpu memory is a little hard to parse and is not super clear about how the first chunk is managed. This adds a little more clarity to the situation. There is also quite a bit of tricky logic in the pcpu_build_alloc_info. This adds a restructure of a comment to add a little more information. Unfortunately, you will still have to piece together a handful of other comments too, but should help direct you to the meaningful comments. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-07-15 22:23:09 -04:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: initialize best_upa variable Tom reported this finding from clang 10's static analysis [1]. Due to the way the code is written, it will always see a successful loop iteration. Instead of setting an initial value, check that it was set instead with BUG_ON() because 0 units per allocation is bogus. [1] https://lore.kernel.org/lkml/20210515180817.1751084-1-trix@redhat.com/ Reported-by: Tom Rix <trix@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-14 14:42:05 +00:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

mm/percpu: use offset_in_page macro linux/mm.h provides offset_in_page() macro. Let's use already predefined macro instead of (addr & ~PAGE_MASK). Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2015-11-05 18:46:43 -08:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: initialize best_upa variable Tom reported this finding from clang 10's static analysis [1]. Due to the way the code is written, it will always see a successful loop iteration. Instead of setting an initial value, check that it was set instead with BUG_ON() because 0 units per allocation is bogus. [1] https://lore.kernel.org/lkml/20210515180817.1751084-1-trix@redhat.com/ Reported-by: Tom Rix <trix@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2021-06-14 14:42:05 +00:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: use nr_groups as check condition group_cnt array is defined with NR_CPUS entries, but normally nr_groups will not reach up to NR_CPUS. So there is no issue to the current code. Checking other parts of pcpu_build_alloc_info, use nr_groups as check condition, so make it consistent to use 'group < nr_groups' as for loop check. In case we do have nr_groups equals with NR_CPUS, we could also avoid memory access out of bounds. Signed-off-by: Peng Fan <peng.fan@nxp.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-02-20 13:32:55 +00:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: make @dyn_size always mean min dyn_size in first chunk init functions In pcpu_build_alloc_info() and pcpu_embed_first_chunk(), @dyn_size was ssize_t, -1 meant auto-size, 0 forced 0 and positive meant minimum size. There's no use case for forcing 0 and the upcoming early alloc support always requires non-zero dynamic size. Make @dyn_size always mean minimum dyn_size. While at it, make pcpu_build_alloc_info() static which doesn't have any external caller as suggested by David Rientjes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com>

2010-06-27 18:49:59 +02:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

mm: percpu: add pcpu_fc_cpu_to_node_fn_t typedef Add pcpu_fc_cpu_to_node_fn_t and pass it into pcpu_fc_alloc_fn_t, pcpu first chunk allocation will call it to alloc memblock on the corresponding node by it, this is prepare for the next patch. Link: https://lkml.kernel.org/r/20211216112359.103822-3-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:45 -08:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: make @dyn_size always mean min dyn_size in first chunk init functions In pcpu_build_alloc_info() and pcpu_embed_first_chunk(), @dyn_size was ssize_t, -1 meant auto-size, 0 forced 0 and positive meant minimum size. There's no use case for forcing 0 and the upcoming early alloc support always requires non-zero dynamic size. Make @dyn_size always mean minimum dyn_size. While at it, make pcpu_build_alloc_info() static which doesn't have any external caller as suggested by David Rientjes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com>

2010-06-27 18:49:59 +02:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: make @dyn_size always mean min dyn_size in first chunk init functions In pcpu_build_alloc_info() and pcpu_embed_first_chunk(), @dyn_size was ssize_t, -1 meant auto-size, 0 forced 0 and positive meant minimum size. There's no use case for forcing 0 and the upcoming early alloc support always requires non-zero dynamic size. Make @dyn_size always mean minimum dyn_size. While at it, make pcpu_build_alloc_info() static which doesn't have any external caller as suggested by David Rientjes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com>

2010-06-27 18:49:59 +02:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

mm/percpu.c: correct max_distance calculation for pcpu_embed_first_chunk() pcpu_embed_first_chunk() calculates the range a percpu chunk spans into @max_distance and uses it to ensure that a chunk is not too big compared to the total vmalloc area. However, during calculation, it used incorrect top address by adding a unit size to the highest group's base address. This can make the calculated max_distance slightly smaller than the actual distance although given the scale of values involved the error is very unlikely to have an actual impact. Fix this issue by adding the group's size instead of a unit size. BTW, The type of variable max_distance is changed from size_t to unsigned long too based on below consideration: - type unsigned long usually have same width with IP core registers and can be applied at here very well - make @max_distance type consistent with the operand calculated against it such as @ai->groups[i].base_offset and macro VMALLOC_TOTAL - type unsigned long is more universal then size_t, size_t is type defined to unsigned int or unsigned long among various ARCHs usually Signed-off-by: zijun_hu <zijun_hu@htc.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2016-10-05 21:19:11 +08:00

percpu: Make pcpu_setup_first_chunk() void function pcpu_setup_first_chunk() will panic or BUG_ON if the are some error and doesn't return any error, hence it can be defined to return void. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: fixed kbuild warning for pcpu_page_first_chunk()]

2019-07-03 16:25:52 +08:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

x86: implement percpu_alloc kernel parameter According to Andi, it isn't clear whether lpage allocator is worth the trouble as there are many processors where PMD TLB is far scarcer than PTE TLB. The advantage or disadvantage probably depends on the actual size of percpu area and specific processor. As performance degradation due to TLB pressure tends to be highly workload specific and subtle, it is difficult to decide which way to go without more data. This patch implements percpu_alloc kernel parameter to allow selecting which first chunk allocator to use to ease debugging and testing. While at it, make sure all the failure paths report why something failed to help determining why certain allocator isn't working. Also, kill the "Great future plan" comment which had already been realized quite some time ago. [ Impact: allow explicit percpu first chunk allocator selection ] Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jan Beulich <JBeulich@novell.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-06-22 11:56:24 +09:00

memblock: drop memblock_alloc_*_nopanic() variants As all the memblock allocation functions return NULL in case of error rather than panic(), the duplicates with _nopanic suffix can be removed. Link: http://lkml.kernel.org/r/1548057848-15136-22-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Petr Mladek <pmladek@suse.com> [printk] Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:42 -07:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

x86: implement percpu_alloc kernel parameter According to Andi, it isn't clear whether lpage allocator is worth the trouble as there are many processors where PMD TLB is far scarcer than PTE TLB. The advantage or disadvantage probably depends on the actual size of percpu area and specific processor. As performance degradation due to TLB pressure tends to be highly workload specific and subtle, it is difficult to decide which way to go without more data. This patch implements percpu_alloc kernel parameter to allow selecting which first chunk allocator to use to ease debugging and testing. While at it, make sure all the failure paths report why something failed to help determining why certain allocator isn't working. Also, kill the "Great future plan" comment which had already been realized quite some time ago. [ Impact: allow explicit percpu first chunk allocator selection ] Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jan Beulich <JBeulich@novell.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-06-22 11:56:24 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

mm/percpu.c: fix potential memory leakage for pcpu_embed_first_chunk() in order to ensure the percpu group areas within a chunk aren't distributed too sparsely, pcpu_embed_first_chunk() goes to error handling path when a chunk spans over 3/4 VMALLOC area, however, during the error handling, it forget to free the memory allocated for all percpu groups by going to label @out_free other than @out_free_areas. it will cause memory leakage issue if the rare scene really happens, in order to fix the issue, we check chunk spanned area immediately after completing memory allocation for all percpu groups, we go to label @out_free_areas to free the memory then return if the checking is failed. in order to verify the approach, we dump all memory allocated then enforce the jump then dump all memory freed, the result is okay after checking whether we free all memory we allocate in this function. BTW, The approach is chosen after thinking over the below scenes - we don't go to label @out_free directly to fix this issue since we maybe free several allocated memory blocks twice - the aim of jumping after pcpu_setup_first_chunk() is bypassing free usable memory other than handling error, moreover, the function does not return error code in any case, it either panics due to BUG_ON() or return 0. Signed-off-by: zijun_hu <zijun_hu@htc.com> Tested-by: zijun_hu <zijun_hu@htc.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2016-10-05 21:30:24 +08:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

kmemleak: Handle percpu memory allocation This patch adds kmemleak callbacks from the percpu allocator, reducing a number of false positives caused by kmemleak not scanning such memory blocks. The percpu chunks are never reported as leaks because of current kmemleak limitations with the __percpu pointer not pointing directly to the actual chunks. Reported-by: Huajun Li <huajun.li.lee@gmail.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2011-09-26 17:12:53 +01:00

mm: percpu: use kmemleak_ignore_phys() instead of kmemleak_free() Kmemleak recently added a rbtree to store the objects allocted with physical address. Those objects can't be freed with kmemleak_free(). According to the comments, percpu allocations are tracked by kmemleak separately. Kmemleak_free() was used to avoid the unnecessary tracking. If kmemleak_free() fails, those objects would be scanned by kmemleak, which is unnecessary but shouldn't lead to other effects. Use kmemleak_ignore_phys() instead of kmemleak_free() for those objects. Link: https://lkml.kernel.org/r/20220705113158.127600-1-patrick.wang.shcn@gmail.com Fixes: 0c24e061196c ("mm: kmemleak: add rbtree and store physical address for objects allocated with PA") Signed-off-by: Patrick Wang <patrick.wang.shcn@gmail.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2022-07-05 19:31:58 +08:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

mm/percpu.c: fix potential memory leakage for pcpu_embed_first_chunk() in order to ensure the percpu group areas within a chunk aren't distributed too sparsely, pcpu_embed_first_chunk() goes to error handling path when a chunk spans over 3/4 VMALLOC area, however, during the error handling, it forget to free the memory allocated for all percpu groups by going to label @out_free other than @out_free_areas. it will cause memory leakage issue if the rare scene really happens, in order to fix the issue, we check chunk spanned area immediately after completing memory allocation for all percpu groups, we go to label @out_free_areas to free the memory then return if the checking is failed. in order to verify the approach, we dump all memory allocated then enforce the jump then dump all memory freed, the result is okay after checking whether we free all memory we allocate in this function. BTW, The approach is chosen after thinking over the below scenes - we don't go to label @out_free directly to fix this issue since we maybe free several allocated memory blocks twice - the aim of jumping after pcpu_setup_first_chunk() is bypassing free usable memory other than handling error, moreover, the function does not return error code in any case, it either panics due to BUG_ON() or return 0. Signed-off-by: zijun_hu <zijun_hu@htc.com> Tested-by: zijun_hu <zijun_hu@htc.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2016-10-05 21:30:24 +08:00

percpu: pcpu_embed_first_chunk() should free unused parts after all allocs are complete pcpu_embed_first_chunk() allocates memory for each node, copies percpu data and frees unused portions of it before proceeding to the next group. This assumes that allocations for different nodes doesn't overlap; however, depending on memory topology, the bootmem allocator may end up allocating memory from a different node than the requested one which may overlap with the portion freed from one of the previous percpu areas. This leads to percpu groups for different nodes overlapping which is a serious bug. This patch separates out copy & partial free from the allocation loop such that all allocations are complete before partial frees happen. This also fixes overlapping frees which could happen on allocation failure path - out_free_areas path frees whole groups but the groups could have portions freed at that point. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org Reported-by: "Pavel V. Panteleev" <pp_84@mail.ru> Tested-by: "Pavel V. Panteleev" <pp_84@mail.ru> LKML-Reference: <E1SNhwY-0007ui-V7.pp_84-mail-ru@f220.mail.ru>

2012-04-27 08:42:53 -07:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

x86: implement percpu_alloc kernel parameter According to Andi, it isn't clear whether lpage allocator is worth the trouble as there are many processors where PMD TLB is far scarcer than PTE TLB. The advantage or disadvantage probably depends on the actual size of percpu area and specific processor. As performance degradation due to TLB pressure tends to be highly workload specific and subtle, it is difficult to decide which way to go without more data. This patch implements percpu_alloc kernel parameter to allow selecting which first chunk allocator to use to ease debugging and testing. While at it, make sure all the failure paths report why something failed to help determining why certain allocator isn't working. Also, kill the "Great future plan" comment which had already been realized quite some time ago. [ Impact: allow explicit percpu first chunk allocator selection ] Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jan Beulich <JBeulich@novell.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-06-22 11:56:24 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: make embedding first chunk allocator check vmalloc space size Embedding first chunk allocator maintains the distances between units in the vmalloc area and thus needs vmalloc space to be larger than the maximum distances between units; otherwise, it wouldn't be able to create any dynamic chunks. This patch makes the embedding first chunk allocator check vmalloc space size and if the maximum distance between units is larger than 75% of it, print warning and, if page mapping allocator is available, fail initialization so that the system falls back onto it. This should work around percpu allocation failure problems on certain sparc64 configurations where distances between NUMA nodes are larger than the vmalloc area and makes percpu allocator more robust for future configurations. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 18:46:01 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: make embedding first chunk allocator check vmalloc space size Embedding first chunk allocator maintains the distances between units in the vmalloc area and thus needs vmalloc space to be larger than the maximum distances between units; otherwise, it wouldn't be able to create any dynamic chunks. This patch makes the embedding first chunk allocator check vmalloc space size and if the maximum distance between units is larger than 75% of it, print warning and, if page mapping allocator is available, fail initialization so that the system falls back onto it. This should work around percpu allocation failure problems on certain sparc64 configurations where distances between NUMA nodes are larger than the vmalloc area and makes percpu allocator more robust for future configurations. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-09-24 18:46:01 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: stop printing kernel addresses Since commit ad67b74d2469d9b8 ("printk: hash addresses printed with %p"), at boot "____ptrval____" is printed instead of actual addresses: percpu: Embedded 38 pages/cpu @(____ptrval____) s124376 r0 d31272 u524288 Instead of changing the print to "%px", and leaking kernel addresses, just remove the print completely, cfr. e.g. commit 071929dbdd865f77 ("arm64: Stop printing the virtual memory layout"). Signed-off-by: Matteo Croce <mcroce@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-03-18 02:32:36 +01:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: Make pcpu_setup_first_chunk() void function pcpu_setup_first_chunk() will panic or BUG_ON if the are some error and doesn't return any error, hence it can be defined to return void. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: fixed kbuild warning for pcpu_page_first_chunk()]

2019-07-03 16:25:52 +08:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

2013-09-17 16:57:34 +02:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

2013-09-17 16:57:34 +02:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: update embedding first chunk allocator to handle sparse units Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:52 +09:00

memblock: use memblock_free for freeing virtual pointers Rename memblock_free_ptr() to memblock_free() and use memblock_free() when freeing a virtual pointer so that memblock_free() will be a counterpart of memblock_alloc() The callers are updated with the below semantic patch and manual addition of (void *) casting to pointers that are represented by unsigned long variables. @@ identifier vaddr; expression size; @@ ( - memblock_phys_free(__pa(vaddr), size); + memblock_free(vaddr, size); | - memblock_free_ptr(vaddr, size); + memblock_free(vaddr, size); ) [sfr@canb.auug.org.au: fixup] Link: https://lkml.kernel.org/r/20211018192940.3d1d532f@canb.auug.org.au Link: https://lkml.kernel.org/r/20210930185031.18648-7-rppt@kernel.org Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Juergen Gross <jgross@suse.com> Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2021-11-05 13:43:22 -07:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

mm/percpu: Remove some local variables in pcpu_populate_pte In function pcpu_populate_pte there are already variable defined, it can be reused for later use, here remove duplicated local variables. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-12 11:16:20 +08:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

mm/percpu: Remove some local variables in pcpu_populate_pte In function pcpu_populate_pte there are already variable defined, it can be reused for later use, here remove duplicated local variables. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-12 11:16:20 +08:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

mm/percpu: Remove some local variables in pcpu_populate_pte In function pcpu_populate_pte there are already variable defined, it can be reused for later use, here remove duplicated local variables. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-12 11:16:20 +08:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

mm/percpu: Remove some local variables in pcpu_populate_pte In function pcpu_populate_pte there are already variable defined, it can be reused for later use, here remove duplicated local variables. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-12 11:16:20 +08:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

mm/percpu: Remove some local variables in pcpu_populate_pte In function pcpu_populate_pte there are already variable defined, it can be reused for later use, here remove duplicated local variables. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-12 11:16:20 +08:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

mm/percpu: Remove some local variables in pcpu_populate_pte In function pcpu_populate_pte there are already variable defined, it can be reused for later use, here remove duplicated local variables. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-07-12 11:16:20 +08:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: rename 4k first chunk allocator to page Page size isn't always 4k depending on arch and configuration. Rename 4k first chunk allocator to page. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Howells <dhowells@redhat.com>

2009-08-14 15:00:49 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

mm: percpu: add pcpu_fc_cpu_to_node_fn_t typedef Add pcpu_fc_cpu_to_node_fn_t and pass it into pcpu_fc_alloc_fn_t, pcpu first chunk allocation will call it to alloc memblock on the corresponding node by it, this is prepare for the next patch. Link: https://lkml.kernel.org/r/20211216112359.103822-3-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:45 -08:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: rename 4k first chunk allocator to page Page size isn't always 4k depending on arch and configuration. Rename 4k first chunk allocator to page. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Howells <dhowells@redhat.com>

2009-08-14 15:00:49 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: make 4k first chunk allocator map memory At first, percpu first chunk was always setup page-by-page by the generic code. To add other allocators, different parts of the generic initialization was made optional. Now we have three allocators - embed, remap and 4k. embed and remap fully handle allocation and mapping of the first chunk while 4k still depends on generic code for those. This makes the generic alloc/map paths specifci to 4k and makes the code unnecessary complicated with optional generic behaviors. This patch makes the 4k allocator to allocate and map memory directly instead of depending on the generic code. The only outside visible change is that now dynamic area in the first chunk is allocated up-front instead of on-demand. This doesn't make any meaningful difference as the area is minimal (usually less than a page, just enough to fill the alignment) on 4k allocator. Plus, dynamic area in the first chunk usually gets fully used anyway. This will allow simplification of pcpu_setpu_first_chunk() and removal of chunk->page array. [ Impact: no outside visible change other than up-front allocation of dyn area ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: rename 4k first chunk allocator to page Page size isn't always 4k depending on arch and configuration. Rename 4k first chunk allocator to page. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Howells <dhowells@redhat.com>

2009-08-14 15:00:49 +09:00

percpu: drop pcpu_chunk->page[] percpu core doesn't need to tack all the allocated pages. It needs to know whether certain pages are populated and a way to reverse map address to page when freeing. This patch drops pcpu_chunk->page[] and use populated bitmap and vmalloc_to_page() lookup instead. Using vmalloc_to_page() exclusively is also possible but complicates first chunk handling, inflates cache footprint and prevents non-standard memory allocation for percpu memory. pcpu_chunk->page[] was used to track each page's allocation and allowed asymmetric population which happens during failure path; however, with single bitmap for all units, this is no longer possible. Bite the bullet and rewrite (de)populate functions so that things are done in clearly separated steps such that asymmetric population doesn't happen. This makes the (de)population process much more modular and will also ease implementing non-standard memory usage in the future (e.g. large pages). This makes @get_page_fn parameter to pcpu_setup_first_chunk() unnecessary. The parameter is dropped and all first chunk helpers are updated accordingly. Please note that despite the volume most changes to first chunk helpers are symbol renames for variables which don't need to be referenced outside of the helper anymore. This change reduces memory usage and cache footprint of pcpu_chunk. Now only #unit_pages bits are necessary per chunk. [ Impact: reduced memory usage and cache footprint for bookkeeping ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: drop pcpu_chunk->page[] percpu core doesn't need to tack all the allocated pages. It needs to know whether certain pages are populated and a way to reverse map address to page when freeing. This patch drops pcpu_chunk->page[] and use populated bitmap and vmalloc_to_page() lookup instead. Using vmalloc_to_page() exclusively is also possible but complicates first chunk handling, inflates cache footprint and prevents non-standard memory allocation for percpu memory. pcpu_chunk->page[] was used to track each page's allocation and allowed asymmetric population which happens during failure path; however, with single bitmap for all units, this is no longer possible. Bite the bullet and rewrite (de)populate functions so that things are done in clearly separated steps such that asymmetric population doesn't happen. This makes the (de)population process much more modular and will also ease implementing non-standard memory usage in the future (e.g. large pages). This makes @get_page_fn parameter to pcpu_setup_first_chunk() unnecessary. The parameter is dropped and all first chunk helpers are updated accordingly. Please note that despite the volume most changes to first chunk helpers are symbol renames for variables which don't need to be referenced outside of the helper anymore. This change reduces memory usage and cache footprint of pcpu_chunk. Now only #unit_pages bits are necessary per chunk. [ Impact: reduced memory usage and cache footprint for bookkeeping ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

percpu: Make pcpu_setup_first_chunk() void function pcpu_setup_first_chunk() will panic or BUG_ON if the are some error and doesn't return any error, hence it can be defined to return void. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: fixed kbuild warning for pcpu_page_first_chunk()]

2019-07-03 16:25:52 +08:00

mm/percpu.c: fix panic triggered by BUG_ON() falsely As shown by pcpu_build_alloc_info(), the number of units within a percpu group is deduced by rounding up the number of CPUs within the group to @upa boundary/ Therefore, the number of CPUs isn't equal to the units's if it isn't aligned to @upa normally. However, pcpu_page_first_chunk() uses BUG_ON() to assert that one number is equal to the other roughly, so a panic is maybe triggered by the BUG_ON() incorrectly. In order to fix this issue, the number of CPUs is rounded up then compared with units's and the BUG_ON() is replaced with a warning and return of an error code as well, to keep system alive as much as possible. Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com Signed-off-by: zijun_hu <zijun_hu@htc.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-12-12 16:45:02 -08:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: rename 4k first chunk allocator to page Page size isn't always 4k depending on arch and configuration. Rename 4k first chunk allocator to page. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Howells <dhowells@redhat.com>

2009-08-14 15:00:49 +09:00

percpu: make @dyn_size always mean min dyn_size in first chunk init functions In pcpu_build_alloc_info() and pcpu_embed_first_chunk(), @dyn_size was ssize_t, -1 meant auto-size, 0 forced 0 and positive meant minimum size. There's no use case for forcing 0 and the upcoming early alloc support always requires non-zero dynamic size. Make @dyn_size always mean minimum dyn_size. While at it, make pcpu_build_alloc_info() static which doesn't have any external caller as suggested by David Rientjes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com>

2010-06-27 18:49:59 +02:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

mm/percpu.c: fix panic triggered by BUG_ON() falsely As shown by pcpu_build_alloc_info(), the number of units within a percpu group is deduced by rounding up the number of CPUs within the group to @upa boundary/ Therefore, the number of CPUs isn't equal to the units's if it isn't aligned to @upa normally. However, pcpu_page_first_chunk() uses BUG_ON() to assert that one number is equal to the other roughly, so a panic is maybe triggered by the BUG_ON() incorrectly. In order to fix this issue, the number of CPUs is rounded up then compared with units's and the BUG_ON() is replaced with a warning and return of an error code as well, to keep system alive as much as possible. Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com Signed-off-by: zijun_hu <zijun_hu@htc.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-12-12 16:45:02 -08:00

mm: percpu: remove unnecessary unlikely() WARN_ON() already contains an unlikely(), so it's not necessary to wrap it into another. Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com> Cc: Tejun Heo <tj@kernel.org> Cc: zijun_hu <zijun_hu@htc.com> Cc: Christoph Lameter <cl@linux.com> Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Dennis Zhou <dennis@kernel.org>

2018-08-31 22:44:22 +03:00

mm/percpu.c: fix panic triggered by BUG_ON() falsely As shown by pcpu_build_alloc_info(), the number of units within a percpu group is deduced by rounding up the number of CPUs within the group to @upa boundary/ Therefore, the number of CPUs isn't equal to the units's if it isn't aligned to @upa normally. However, pcpu_page_first_chunk() uses BUG_ON() to assert that one number is equal to the other roughly, so a panic is maybe triggered by the BUG_ON() incorrectly. In order to fix this issue, the number of CPUs is rounded up then compared with units's and the BUG_ON() is replaced with a warning and return of an error code as well, to keep system alive as much as possible. Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com Signed-off-by: zijun_hu <zijun_hu@htc.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-12-12 16:45:02 -08:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

2018-10-30 15:09:57 -07:00

mm/percpu: add checks for the return value of memblock_alloc*() Add panic() calls if memblock_alloc() returns NULL. The panic() format duplicates the one used by memblock itself and in order to avoid explosion with long parameters list replace open coded allocation size calculations with a local variable. Link: http://lkml.kernel.org/r/1548057848-15136-17-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:15 -07:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: make 4k first chunk allocator map memory At first, percpu first chunk was always setup page-by-page by the generic code. To add other allocators, different parts of the generic initialization was made optional. Now we have three allocators - embed, remap and 4k. embed and remap fully handle allocation and mapping of the first chunk while 4k still depends on generic code for those. This makes the generic alloc/map paths specifci to 4k and makes the code unnecessary complicated with optional generic behaviors. This patch makes the 4k allocator to allocate and map memory directly instead of depending on the generic code. The only outside visible change is that now dynamic area in the first chunk is allocated up-front instead of on-demand. This doesn't make any meaningful difference as the area is minimal (usually less than a page, just enough to fill the alignment) on 4k allocator. Plus, dynamic area in the first chunk usually gets fully used anyway. This will allow simplification of pcpu_setpu_first_chunk() and removal of chunk->page array. [ Impact: no outside visible change other than up-front allocation of dyn area ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

mm/percpu.c: fix panic triggered by BUG_ON() falsely As shown by pcpu_build_alloc_info(), the number of units within a percpu group is deduced by rounding up the number of CPUs within the group to @upa boundary/ Therefore, the number of CPUs isn't equal to the units's if it isn't aligned to @upa normally. However, pcpu_page_first_chunk() uses BUG_ON() to assert that one number is equal to the other roughly, so a panic is maybe triggered by the BUG_ON() incorrectly. In order to fix this issue, the number of CPUs is rounded up then compared with units's and the BUG_ON() is replaced with a warning and return of an error code as well, to keep system alive as much as possible. Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com Signed-off-by: zijun_hu <zijun_hu@htc.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-12-12 16:45:02 -08:00

percpu: drop pcpu_chunk->page[] percpu core doesn't need to tack all the allocated pages. It needs to know whether certain pages are populated and a way to reverse map address to page when freeing. This patch drops pcpu_chunk->page[] and use populated bitmap and vmalloc_to_page() lookup instead. Using vmalloc_to_page() exclusively is also possible but complicates first chunk handling, inflates cache footprint and prevents non-standard memory allocation for percpu memory. pcpu_chunk->page[] was used to track each page's allocation and allowed asymmetric population which happens during failure path; however, with single bitmap for all units, this is no longer possible. Bite the bullet and rewrite (de)populate functions so that things are done in clearly separated steps such that asymmetric population doesn't happen. This makes the (de)population process much more modular and will also ease implementing non-standard memory usage in the future (e.g. large pages). This makes @get_page_fn parameter to pcpu_setup_first_chunk() unnecessary. The parameter is dropped and all first chunk helpers are updated accordingly. Please note that despite the volume most changes to first chunk helpers are symbol renames for variables which don't need to be referenced outside of the helper anymore. This change reduces memory usage and cache footprint of pcpu_chunk. Now only #unit_pages bits are necessary per chunk. [ Impact: reduced memory usage and cache footprint for bookkeeping ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

mm: percpu: use pr_fmt to prefix output Use the normal mechanism to make the logging output consistently "percpu:" instead of a mix of "PERCPU:" and "percpu:" Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-03-17 14:19:53 -07:00

mm/percpu.c: fix panic triggered by BUG_ON() falsely As shown by pcpu_build_alloc_info(), the number of units within a percpu group is deduced by rounding up the number of CPUs within the group to @upa boundary/ Therefore, the number of CPUs isn't equal to the units's if it isn't aligned to @upa normally. However, pcpu_page_first_chunk() uses BUG_ON() to assert that one number is equal to the other roughly, so a panic is maybe triggered by the BUG_ON() incorrectly. In order to fix this issue, the number of CPUs is rounded up then compared with units's and the BUG_ON() is replaced with a warning and return of an error code as well, to keep system alive as much as possible. Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com Signed-off-by: zijun_hu <zijun_hu@htc.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-12-12 16:45:02 -08:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

kmemleak: Handle percpu memory allocation This patch adds kmemleak callbacks from the percpu allocator, reducing a number of false positives caused by kmemleak not scanning such memory blocks. The percpu chunks are never reported as leaks because of current kmemleak limitations with the __percpu pointer not pointing directly to the actual chunks. Reported-by: Huajun Li <huajun.li.lee@gmail.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2011-09-26 17:12:53 +01:00

mm: percpu: use kmemleak_ignore_phys() instead of kmemleak_free() Kmemleak recently added a rbtree to store the objects allocted with physical address. Those objects can't be freed with kmemleak_free(). According to the comments, percpu allocations are tracked by kmemleak separately. Kmemleak_free() was used to avoid the unnecessary tracking. If kmemleak_free() fails, those objects would be scanned by kmemleak, which is unnecessary but shouldn't lead to other effects. Use kmemleak_ignore_phys() instead of kmemleak_free() for those objects. Link: https://lkml.kernel.org/r/20220705113158.127600-1-patrick.wang.shcn@gmail.com Fixes: 0c24e061196c ("mm: kmemleak: add rbtree and store physical address for objects allocated with PA") Signed-off-by: Patrick Wang <patrick.wang.shcn@gmail.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2022-07-05 19:31:58 +08:00

percpu: drop pcpu_chunk->page[] percpu core doesn't need to tack all the allocated pages. It needs to know whether certain pages are populated and a way to reverse map address to page when freeing. This patch drops pcpu_chunk->page[] and use populated bitmap and vmalloc_to_page() lookup instead. Using vmalloc_to_page() exclusively is also possible but complicates first chunk handling, inflates cache footprint and prevents non-standard memory allocation for percpu memory. pcpu_chunk->page[] was used to track each page's allocation and allowed asymmetric population which happens during failure path; however, with single bitmap for all units, this is no longer possible. Bite the bullet and rewrite (de)populate functions so that things are done in clearly separated steps such that asymmetric population doesn't happen. This makes the (de)population process much more modular and will also ease implementing non-standard memory usage in the future (e.g. large pages). This makes @get_page_fn parameter to pcpu_setup_first_chunk() unnecessary. The parameter is dropped and all first chunk helpers are updated accordingly. Please note that despite the volume most changes to first chunk helpers are symbol renames for variables which don't need to be referenced outside of the helper anymore. This change reduces memory usage and cache footprint of pcpu_chunk. Now only #unit_pages bits are necessary per chunk. [ Impact: reduced memory usage and cache footprint for bookkeeping ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

mm/percpu.c: fix panic triggered by BUG_ON() falsely As shown by pcpu_build_alloc_info(), the number of units within a percpu group is deduced by rounding up the number of CPUs within the group to @upa boundary/ Therefore, the number of CPUs isn't equal to the units's if it isn't aligned to @upa normally. However, pcpu_page_first_chunk() uses BUG_ON() to assert that one number is equal to the other roughly, so a panic is maybe triggered by the BUG_ON() incorrectly. In order to fix this issue, the number of CPUs is rounded up then compared with units's and the BUG_ON() is replaced with a warning and return of an error code as well, to keep system alive as much as possible. Link: http://lkml.kernel.org/r/57FCF07C.2020103@zoho.com Signed-off-by: zijun_hu <zijun_hu@htc.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2016-12-12 16:45:02 -08:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: make 4k first chunk allocator map memory At first, percpu first chunk was always setup page-by-page by the generic code. To add other allocators, different parts of the generic initialization was made optional. Now we have three allocators - embed, remap and 4k. embed and remap fully handle allocation and mapping of the first chunk while 4k still depends on generic code for those. This makes the generic alloc/map paths specifci to 4k and makes the code unnecessary complicated with optional generic behaviors. This patch makes the 4k allocator to allocate and map memory directly instead of depending on the generic code. The only outside visible change is that now dynamic area in the first chunk is allocated up-front instead of on-demand. This doesn't make any meaningful difference as the area is minimal (usually less than a page, just enough to fill the alignment) on 4k allocator. Plus, dynamic area in the first chunk usually gets fully used anyway. This will allow simplification of pcpu_setpu_first_chunk() and removal of chunk->page array. [ Impact: no outside visible change other than up-front allocation of dyn area ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: make 4k first chunk allocator map memory At first, percpu first chunk was always setup page-by-page by the generic code. To add other allocators, different parts of the generic initialization was made optional. Now we have three allocators - embed, remap and 4k. embed and remap fully handle allocation and mapping of the first chunk while 4k still depends on generic code for those. This makes the generic alloc/map paths specifci to 4k and makes the code unnecessary complicated with optional generic behaviors. This patch makes the 4k allocator to allocate and map memory directly instead of depending on the generic code. The only outside visible change is that now dynamic area in the first chunk is allocated up-front instead of on-demand. This doesn't make any meaningful difference as the area is minimal (usually less than a page, just enough to fill the alignment) on 4k allocator. Plus, dynamic area in the first chunk usually gets fully used anyway. This will allow simplification of pcpu_setpu_first_chunk() and removal of chunk->page array. [ Impact: no outside visible change other than up-front allocation of dyn area ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: make @dyn_size mandatory for pcpu_setup_first_chunk() Now that all actual first chunk allocation and copying happen in the first chunk allocators and helpers, there's no reason for pcpu_setup_first_chunk() to try to determine @dyn_size automatically. The only left user is page first chunk allocator. Make it determine dyn_size like other allocators and make @dyn_size mandatory for pcpu_setup_first_chunk(). Signed-off-by: Tejun Heo <tj@kernel.org>

2009-08-14 15:00:50 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: make 4k first chunk allocator map memory At first, percpu first chunk was always setup page-by-page by the generic code. To add other allocators, different parts of the generic initialization was made optional. Now we have three allocators - embed, remap and 4k. embed and remap fully handle allocation and mapping of the first chunk while 4k still depends on generic code for those. This makes the generic alloc/map paths specifci to 4k and makes the code unnecessary complicated with optional generic behaviors. This patch makes the 4k allocator to allocate and map memory directly instead of depending on the generic code. The only outside visible change is that now dynamic area in the first chunk is allocated up-front instead of on-demand. This doesn't make any meaningful difference as the area is minimal (usually less than a page, just enough to fill the alignment) on 4k allocator. Plus, dynamic area in the first chunk usually gets fully used anyway. This will allow simplification of pcpu_setpu_first_chunk() and removal of chunk->page array. [ Impact: no outside visible change other than up-front allocation of dyn area ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: drop pcpu_chunk->page[] percpu core doesn't need to tack all the allocated pages. It needs to know whether certain pages are populated and a way to reverse map address to page when freeing. This patch drops pcpu_chunk->page[] and use populated bitmap and vmalloc_to_page() lookup instead. Using vmalloc_to_page() exclusively is also possible but complicates first chunk handling, inflates cache footprint and prevents non-standard memory allocation for percpu memory. pcpu_chunk->page[] was used to track each page's allocation and allowed asymmetric population which happens during failure path; however, with single bitmap for all units, this is no longer possible. Bite the bullet and rewrite (de)populate functions so that things are done in clearly separated steps such that asymmetric population doesn't happen. This makes the (de)population process much more modular and will also ease implementing non-standard memory usage in the future (e.g. large pages). This makes @get_page_fn parameter to pcpu_setup_first_chunk() unnecessary. The parameter is dropped and all first chunk helpers are updated accordingly. Please note that despite the volume most changes to first chunk helpers are symbol renames for variables which don't need to be referenced outside of the helper anymore. This change reduces memory usage and cache footprint of pcpu_chunk. Now only #unit_pages bits are necessary per chunk. [ Impact: reduced memory usage and cache footprint for bookkeeping ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-07-04 08:11:00 +09:00

mm: percpu: add generic pcpu_populate_pte() function With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:53 -08:00

percpu: make 4k first chunk allocator map memory At first, percpu first chunk was always setup page-by-page by the generic code. To add other allocators, different parts of the generic initialization was made optional. Now we have three allocators - embed, remap and 4k. embed and remap fully handle allocation and mapping of the first chunk while 4k still depends on generic code for those. This makes the generic alloc/map paths specifci to 4k and makes the code unnecessary complicated with optional generic behaviors. This patch makes the 4k allocator to allocate and map memory directly instead of depending on the generic code. The only outside visible change is that now dynamic area in the first chunk is allocated up-front instead of on-demand. This doesn't make any meaningful difference as the area is minimal (usually less than a page, just enough to fill the alignment) on 4k allocator. Plus, dynamic area in the first chunk usually gets fully used anyway. This will allow simplification of pcpu_setpu_first_chunk() and removal of chunk->page array. [ Impact: no outside visible change other than up-front allocation of dyn area ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

mm: Introduce flush_cache_vmap_early() The pcpu setup when using the page allocator sets up a new vmalloc mapping very early in the boot process, so early that it cannot use the flush_cache_vmap() function which may depend on structures not yet initialized (for example in riscv, we currently send an IPI to flush other cpus TLB). But on some architectures, we must call flush_cache_vmap(): for example, in riscv, some uarchs can cache invalid TLB entries so we need to flush the new established mapping to avoid taking an exception. So fix this by introducing a new function flush_cache_vmap_early() which is called right after setting the new page table entry and before accessing this new mapping. This new function implements a local flush tlb on riscv and is no-op for other architectures (same as today). Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2023-12-12 22:34:56 +01:00

percpu: make 4k first chunk allocator map memory At first, percpu first chunk was always setup page-by-page by the generic code. To add other allocators, different parts of the generic initialization was made optional. Now we have three allocators - embed, remap and 4k. embed and remap fully handle allocation and mapping of the first chunk while 4k still depends on generic code for those. This makes the generic alloc/map paths specifci to 4k and makes the code unnecessary complicated with optional generic behaviors. This patch makes the 4k allocator to allocate and map memory directly instead of depending on the generic code. The only outside visible change is that now dynamic area in the first chunk is allocated up-front instead of on-demand. This doesn't make any meaningful difference as the area is minimal (usually less than a page, just enough to fill the alignment) on 4k allocator. Plus, dynamic area in the first chunk usually gets fully used anyway. This will allow simplification of pcpu_setpu_first_chunk() and removal of chunk->page array. [ Impact: no outside visible change other than up-front allocation of dyn area ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: stop printing kernel addresses Since commit ad67b74d2469d9b8 ("printk: hash addresses printed with %p"), at boot "____ptrval____" is printed instead of actual addresses: percpu: Embedded 38 pages/cpu @(____ptrval____) s124376 r0 d31272 u524288 Instead of changing the print to "%px", and leaking kernel addresses, just remove the print completely, cfr. e.g. commit 071929dbdd865f77 ("arm64: Stop printing the virtual memory layout"). Signed-off-by: Matteo Croce <mcroce@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>

2019-03-18 02:32:36 +01:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: Make pcpu_setup_first_chunk() void function pcpu_setup_first_chunk() will panic or BUG_ON if the are some error and doesn't return any error, hence it can be defined to return void. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: fixed kbuild warning for pcpu_page_first_chunk()]

2019-07-03 16:25:52 +08:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

memblock: use memblock_free for freeing virtual pointers Rename memblock_free_ptr() to memblock_free() and use memblock_free() when freeing a virtual pointer so that memblock_free() will be a counterpart of memblock_alloc() The callers are updated with the below semantic patch and manual addition of (void *) casting to pointers that are represented by unsigned long variables. @@ identifier vaddr; expression size; @@ ( - memblock_phys_free(__pa(vaddr), size); + memblock_free(vaddr, size); | - memblock_free_ptr(vaddr, size); + memblock_free(vaddr, size); ) [sfr@canb.auug.org.au: fixup] Link: https://lkml.kernel.org/r/20211018192940.3d1d532f@canb.auug.org.au Link: https://lkml.kernel.org/r/20210930185031.18648-7-rppt@kernel.org Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Juergen Gross <jgross@suse.com> Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2021-11-05 13:43:22 -07:00

percpu: introduce pcpu_alloc_info and pcpu_group_info Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: fix build breakage on s390 and cleanup build configuration tests Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly excluded pcpu_build_alloc_info() on SMP configurations which use generic setup_per_cpu_area() like s390. The config ifdefs are becoming confusing. Fix and clean it up by, * Move pcpu_build_alloc_info() right on top of its two users - pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP block. * Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each first chunk function needs to be included and use them to control inclusion of the three functions to reduce confusion. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sachin Sant <sachinp@in.ibm.com>

2010-09-09 18:00:15 +02:00

x86,percpu: generalize 4k first chunk allocator Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>

2009-07-04 08:10:59 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: use dynamic percpu allocator as the default percpu allocator This patch makes most !CONFIG_HAVE_SETUP_PER_CPU_AREA archs use dynamic percpu allocator. The first chunk is allocated using embedding helper and 8k is reserved for modules. This ensures that the new allocator behaves almost identically to the original allocator as long as static percpu variables are concerned, so it shouldn't introduce much breakage. s390 and alpha use custom SHIFT_PERCPU_PTR() to work around addressing range limit the addressing model imposes. Unfortunately, this breaks if the address is specified using a variable, so for now, the two archs aren't converted. The following architectures are affected by this change. * sh * arm * cris * mips * sparc(32) * blackfin * avr32 * parisc (broken, under investigation) * m32r * powerpc(32) As this change makes the dynamic allocator the default one, CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is replaced with its invert - CONFIG_HAVE_LEGACY_PER_CPU_AREA, which is added to yet-to-be converted archs. These archs implement their own setup_per_cpu_areas() and the conversion is not trivial. * powerpc(64) * sparc(64) * ia64 * alpha * s390 Boot and batch alloc/free tests on x86_32 with debug code (x86_32 doesn't use default first chunk initialization). Compile tested on sparc(32), powerpc(32), arm and alpha. Kyle McMartin reported that this change breaks parisc. The problem is still under investigation and he is okay with pushing this patch forward and fixing parisc later. [ Impact: use dynamic allocator for most archs w/o custom percpu setup ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Reviewed-by: Christoph Lameter <cl@linux.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Mikael Starvik <starvik@axis.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Bryan Wu <cooloney@kernel.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Grant Grundler <grundler@parisc-linux.org> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu>

2009-03-30 19:07:44 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: use dynamic percpu allocator as the default percpu allocator This patch makes most !CONFIG_HAVE_SETUP_PER_CPU_AREA archs use dynamic percpu allocator. The first chunk is allocated using embedding helper and 8k is reserved for modules. This ensures that the new allocator behaves almost identically to the original allocator as long as static percpu variables are concerned, so it shouldn't introduce much breakage. s390 and alpha use custom SHIFT_PERCPU_PTR() to work around addressing range limit the addressing model imposes. Unfortunately, this breaks if the address is specified using a variable, so for now, the two archs aren't converted. The following architectures are affected by this change. * sh * arm * cris * mips * sparc(32) * blackfin * avr32 * parisc (broken, under investigation) * m32r * powerpc(32) As this change makes the dynamic allocator the default one, CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is replaced with its invert - CONFIG_HAVE_LEGACY_PER_CPU_AREA, which is added to yet-to-be converted archs. These archs implement their own setup_per_cpu_areas() and the conversion is not trivial. * powerpc(64) * sparc(64) * ia64 * alpha * s390 Boot and batch alloc/free tests on x86_32 with debug code (x86_32 doesn't use default first chunk initialization). Compile tested on sparc(32), powerpc(32), arm and alpha. Kyle McMartin reported that this change breaks parisc. The problem is still under investigation and he is okay with pushing this patch forward and fixing parisc later. [ Impact: use dynamic allocator for most archs w/o custom percpu setup ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Reviewed-by: Christoph Lameter <cl@linux.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Mikael Starvik <starvik@axis.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Bryan Wu <cooloney@kernel.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Grant Grundler <grundler@parisc-linux.org> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu>

2009-03-30 19:07:44 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: use dynamic percpu allocator as the default percpu allocator This patch makes most !CONFIG_HAVE_SETUP_PER_CPU_AREA archs use dynamic percpu allocator. The first chunk is allocated using embedding helper and 8k is reserved for modules. This ensures that the new allocator behaves almost identically to the original allocator as long as static percpu variables are concerned, so it shouldn't introduce much breakage. s390 and alpha use custom SHIFT_PERCPU_PTR() to work around addressing range limit the addressing model imposes. Unfortunately, this breaks if the address is specified using a variable, so for now, the two archs aren't converted. The following architectures are affected by this change. * sh * arm * cris * mips * sparc(32) * blackfin * avr32 * parisc (broken, under investigation) * m32r * powerpc(32) As this change makes the dynamic allocator the default one, CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is replaced with its invert - CONFIG_HAVE_LEGACY_PER_CPU_AREA, which is added to yet-to-be converted archs. These archs implement their own setup_per_cpu_areas() and the conversion is not trivial. * powerpc(64) * sparc(64) * ia64 * alpha * s390 Boot and batch alloc/free tests on x86_32 with debug code (x86_32 doesn't use default first chunk initialization). Compile tested on sparc(32), powerpc(32), arm and alpha. Kyle McMartin reported that this change breaks parisc. The problem is still under investigation and he is okay with pushing this patch forward and fixing parisc later. [ Impact: use dynamic allocator for most archs w/o custom percpu setup ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Reviewed-by: Christoph Lameter <cl@linux.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Mikael Starvik <starvik@axis.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Bryan Wu <cooloney@kernel.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Grant Grundler <grundler@parisc-linux.org> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu>

2009-03-30 19:07:44 +09:00

mm: percpu: add generic pcpu_fc_alloc/free funciton With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2022-01-19 18:07:49 -08:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: use dynamic percpu allocator as the default percpu allocator This patch makes most !CONFIG_HAVE_SETUP_PER_CPU_AREA archs use dynamic percpu allocator. The first chunk is allocated using embedding helper and 8k is reserved for modules. This ensures that the new allocator behaves almost identically to the original allocator as long as static percpu variables are concerned, so it shouldn't introduce much breakage. s390 and alpha use custom SHIFT_PERCPU_PTR() to work around addressing range limit the addressing model imposes. Unfortunately, this breaks if the address is specified using a variable, so for now, the two archs aren't converted. The following architectures are affected by this change. * sh * arm * cris * mips * sparc(32) * blackfin * avr32 * parisc (broken, under investigation) * m32r * powerpc(32) As this change makes the dynamic allocator the default one, CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is replaced with its invert - CONFIG_HAVE_LEGACY_PER_CPU_AREA, which is added to yet-to-be converted archs. These archs implement their own setup_per_cpu_areas() and the conversion is not trivial. * powerpc(64) * sparc(64) * ia64 * alpha * s390 Boot and batch alloc/free tests on x86_32 with debug code (x86_32 doesn't use default first chunk initialization). Compile tested on sparc(32), powerpc(32), arm and alpha. Kyle McMartin reported that this change breaks parisc. The problem is still under investigation and he is okay with pushing this patch forward and fixing parisc later. [ Impact: use dynamic allocator for most archs w/o custom percpu setup ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Reviewed-by: Christoph Lameter <cl@linux.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Mikael Starvik <starvik@axis.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Bryan Wu <cooloney@kernel.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Grant Grundler <grundler@parisc-linux.org> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu>

2009-03-30 19:07:44 +09:00

percpu: add pcpu_unit_offsets[] Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>

2009-08-14 15:00:51 +09:00

percpu: generalize embedding first chunk setup helper Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>

2009-03-10 16:27:48 +09:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

memblock: drop memblock_alloc_*_nopanic() variants As all the memblock allocation functions return NULL in case of error rather than panic(), the duplicates with _nopanic suffix can be removed. Link: http://lkml.kernel.org/r/1548057848-15136-22-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Petr Mladek <pmladek@suse.com> [printk] Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2019-03-11 23:30:42 -07:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

kmemleak: Fix the kmemleak tracking of the percpu areas with !SMP Kmemleak tracks the percpu allocations via a specific API and the originally allocated areas must be removed from kmemleak (via kmemleak_free). The code was already doing this for SMP systems. Reported-by: Sami Liedes <sami.liedes@iki.fi> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2012-05-09 16:55:19 +01:00

mm: percpu: use kmemleak_ignore_phys() instead of kmemleak_free() Kmemleak recently added a rbtree to store the objects allocted with physical address. Those objects can't be freed with kmemleak_free(). According to the comments, percpu allocations are tracked by kmemleak separately. Kmemleak_free() was used to avoid the unnecessary tracking. If kmemleak_free() fails, those objects would be scanned by kmemleak, which is unnecessary but shouldn't lead to other effects. Use kmemleak_ignore_phys() instead of kmemleak_free() for those objects. Link: https://lkml.kernel.org/r/20220705113158.127600-1-patrick.wang.shcn@gmail.com Fixes: 0c24e061196c ("mm: kmemleak: add rbtree and store physical address for objects allocated with PA") Signed-off-by: Patrick Wang <patrick.wang.shcn@gmail.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2022-07-05 19:31:58 +08:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: Make pcpu_setup_first_chunk() void function pcpu_setup_first_chunk() will panic or BUG_ON if the are some error and doesn't return any error, hence it can be defined to return void. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: fixed kbuild warning for pcpu_page_first_chunk()]

2019-07-03 16:25:52 +08:00

percpu: don't forget to free the temporary struct pcpu_alloc_info Unlike the SMP case, the !SMP case does not free the memory for struct pcpu_alloc_info allocated in setup_per_cpu_areas(). And to give it a chance of being reused by the page allocator later, align it to a page boundary just like its size. Signed-off-by: Nicolas Pitre <nico@linaro.org> Acked-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>

2017-10-03 18:29:49 -04:00

percpu: use percpu allocator on UP too On UP, percpu allocations were redirected to kmalloc. This has the following problems. * For certain amount of allocations (determined by PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu allocator can be used before the usual kernel memory allocator is brought online. On SMP, this is used to initialize the kernel memory allocator. * percpu allocator honors alignment upto PAGE_SIZE but kmalloc() doesn't. For example, workqueue makes use of larger alignments for cpu_workqueues. Currently, users of percpu allocators need to handle UP differently, which is somewhat fragile and ugly. Other than small amount of memory, there isn't much to lose by enabling percpu allocator on UP. It can simply use kernel memory based chunk allocation which was added for SMP archs w/o MMUs. This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and makes UP build use percpu-km. As percpu addresses and kernel addresses are always identity mapped and static percpu variables don't need any special treatment, nothing is arch dependent and mm/percpu.c implements generic setup_per_cpu_areas() for UP. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>

2010-09-03 18:22:48 +02:00

percpu: allow limited allocation before slab is online This patch updates percpu allocator such that it can serve limited amount of allocation before slab comes online. This is primarily to allow slab to depend on working percpu allocator. Two parameters, PERCPU_DYNAMIC_EARLY_SIZE and SLOTS, determine how much memory space and allocation map slots are reserved. If this reserved area is exhausted, WARN_ON_ONCE() will trigger and allocation will fail till slab comes online. The following changes are made to implement early alloc. * pcpu_mem_alloc() now checks slab_is_available() * Chunks are allocated using pcpu_mem_alloc() * Init paths make sure ai->dyn_size is at least as large as PERCPU_DYNAMIC_EARLY_SIZE. * Initial alloc maps are allocated in __initdata and copied to kmalloc'd areas once slab is online. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux-foundation.org>

2010-06-27 18:50:00 +02:00

/proc/meminfo: add percpu populated pages count Currently, percpu memory only exposes allocation and utilization information via debugfs. This more or less is only really useful for understanding the fragmentation and allocation information at a per-chunk level with a few global counters. This is also gated behind a config. BPF and cgroup, for example, have seen an increase in use causing increased use of percpu memory. Let's make it easier for someone to identify how much memory is being used. This patch adds the "Percpu" stat to meminfo to more easily look up how much percpu memory is in use. This number includes the cost for all allocated backing pages and not just insight at the per a unit, per chunk level. Metadata is excluded. I think excluding metadata is fair because the backing memory scales with the numbere of cpus and can quickly outweigh the metadata. It also makes this calculation light. Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2018-08-21 21:53:58 -07:00

percpu: implement asynchronous chunk population The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>

2014-09-02 14:46:05 -04:00

3461 lines 103 KiB Raw Permalink Normal View History

3461 lines

103 KiB

Raw Permalink Normal View History