sg_next() is a short function called frequently in I/O paths. Define it
in the header file so it can be inlined into its callers.
Link: https://lkml.kernel.org/r/20250416160615.3571958-1-csander@purestorage.com
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Don't negate 'ret' and simplify the return statement.
No functional changes intended.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Extend the existing hung_task detector test module to support multiple
lock types, including mutex and semaphore, with room for future additions
(e.g., spinlock, etc.). This module creates dummy files under
<debugfs>/hung_task, such as 'mutex' and 'semaphore'. The read process on
any of these files will sleep for enough long time (256 seconds) while
holding the respective lock. As a result, the second process will wait on
the lock for a prolonged duration and be detected by the hung_task
detector.
This change unifies the previous mutex-only sample into a single,
extensible hung_task_tests module, reducing code duplication and improving
maintainability.
Usage is:
> cd /sys/kernel/debug/hung_task
> cat mutex & cat mutex # Test mutex blocking
> cat semaphore & cat semaphore # Test semaphore blocking
Update the Kconfig description to reflect multiple debugfs files support.
Link: https://lkml.kernel.org/r/20250414145945.84916-4-ioworker0@gmail.com
Signed-off-by: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Zi Li <amaindex@outlook.com>
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Stultz <jstultz@google.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Mingzhe Yang <mingzhe.yang@ly.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yongliang Gao <leonylgao@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit 8fa7292fee ("treewide: Switch/rename to timer_delete[_sync]()")
switched del_timer_sync to timer_delete_sync, but did not modify the
comment for o2net_idle_timer(). Now fix it.
Link: https://lkml.kernel.org/r/BDDB1E4E2876C36C+20250411102610.165946-1-wangyuli@uniontech.com
Signed-off-by: WangYuli <wangyuli@uniontech.com>
Acked-by: Joseph Qi <jiangqi903@gmail.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Syzkaller reports an "UBSAN: shift-out-of-bounds in squashfs_bio_read" bug.
Syzkaller forks multiple processes which after mounting the Squashfs
filesystem, issues an ioctl("/dev/loop0", LOOP_SET_BLOCK_SIZE, 0x8000).
Now if this ioctl occurs at the same time another process is in the
process of mounting a Squashfs filesystem on /dev/loop0, the failure
occurs. When this happens the following code in squashfs_fill_super()
fails.
----
msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
msblk->devblksize_log2 = ffz(~msblk->devblksize);
----
sb_min_blocksize() returns 0, which means msblk->devblksize is set to 0.
As a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2
is set to 64.
This subsequently causes the
UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36
shift exponent 64 is too large for 64-bit type 'u64' (aka
'unsigned long long')
This commit adds a check for a 0 return by sb_min_blocksize().
Link: https://lkml.kernel.org/r/20250409024747.876480-1-phillip@squashfs.org.uk
Fixes: 0aa6661905 ("Squashfs: super block operations")
Reported-by: syzbot+65761fc25a137b9c8c6e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/67f0dd7a.050a0220.0a13.0230.GAE@google.com/
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This reduces single-threaded overhead as it avoids one lock+irq trip on
exit.
It also improves scalability of spawning and killing threads within one
process (just shy of 5% when doing it on 24 cores on my test jig).
Both routines are moved below kcov and kmsan exit, which should be
harmless.
Link: https://lkml.kernel.org/r/20250319195436.1864415-1-mjguzik@gmail.com
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Current errseq implementation depends on a very special precondition that
macro MAX_ERRNO must be (2^n - 1).
Eliminate the limitation by
- redefining macro ERRSEQ_SHIFT
- defining a new macro ERRNO_MASK instead of MAX_ERRNO for errno mask.
There is no plan to change the value of MAX_ERRNO, but this makes the
implementation more generic and eliminates the BUILD_BUG_ON().
Link: https://lkml.kernel.org/r/20250407-improve_errseq-v1-1-7b27cbeb8298@quicinc.com
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In some places in the kernel there is a design pattern for sysfs
attributes to use kstrtobool() in store() and str_enabled_disabled() in
show().
This is counterintuitive to interact with because kstrtobool() takes
on/off but str_enabled_disabled() shows enabled/disabled. Some of those
sysfs uses could switch to str_on_off() but for some attributes
enabled/disabled really makes more sense.
Add support for kstrtobool() to accept enabled/disabled.
Link: https://lkml.kernel.org/r/20250321022538.1532445-1-superm1@kernel.org
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
While the natural choice of PTR_IF() is kconfig.h, the latter is too broad
to include C code and actually the macro was moved out from there in the
past. But kernel.h is neither a good choice for that. Move it to
util_macros.h. Do the same for u64_to_user_ptr().
While moving, add necessary documentation.
Link: https://lkml.kernel.org/r/20250324105228.775784-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexandru Ardelean <aardelean@baylibre.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "kernel.h: Move out a couple of macros and constants".
kernel.h hosts a couple of macros and constants that may be better placed.
Do that. Also add missing documentation. No functional changes
intended.
This patch (of 2):
Headers shouldn't be forced to include <linux/kernel.h> just to
gain these simple constants.
Link: https://lkml.kernel.org/r/20250324105228.775784-1-andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20250324105228.775784-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexandru Ardelean <aardelean@baylibre.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This reduces log-msgs during boot from many pages to ~10 occurrences. I
didn't investigate why it wasn't just 1, maybe its a low-level service to
other modules, re-probed by each of them ?
Link: https://lkml.kernel.org/r/20250325235156.663269-4-jim.cromie@gmail.com
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Louis Chauvet <louis.chauvet@bootlin.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a paragraph of advice qualifying the general do-while-0 advice, noting
3 possible misguidings. reduce one ERROR to WARN, for the case I actually
encountered.
And add 'static_assert' to named exceptions, along with some additional
comments about named exceptions vs (detection of) declarative construction
primitives (union, struct, [], etc).
Link: https://lkml.kernel.org/r/20250325235156.663269-3-jim.cromie@gmail.com
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Louis Chauvet <louis.chauvet@bootlin.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "2 checkpatch fixes, one pr_info_once".
2 small tweaks to checkpatch,
1 reducing several pages of powernow "not-relevant-here" log-msgs to a few lines
This patch (of 3):
We currently get:
WARNING: Argument 'name' is not used in function-like macro
on:
#define DRM_CLASSMAP_USE(name) /* nothing here */
Following this advice is wrong here, and shouldn't be fixed by ignoring
args altogether; the macro should properly fail if invoked with 0 or 2+
args.
Link: https://lkml.kernel.org/r/20250325235156.663269-1-jim.cromie@gmail.com
Link: https://lkml.kernel.org/r/20250325235156.663269-2-jim.cromie@gmail.com
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Acked-by: Joe Perches <joe@perches.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc:"Rafael J. Wysocki" <rafael@kernel.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
proc_mem_open() can return an errno, NULL, or mm_struct*. If it fails to
acquire mm, it returns NULL, but the caller does not check for the case
when the return value is NULL.
The following conditions lead to failure in acquiring mm:
- The task is a kernel thread (PF_KTHREAD)
- The task is exiting (PF_EXITING)
Changes:
- Add documentation comments for the return value of proc_mem_open().
- Add checks in the caller to return -ESRCH when proc_mem_open()
returns NULL.
Link: https://lkml.kernel.org/r/20250404063357.78891-1-superman.xpt@gmail.com
Reported-by: syzbot+f9238a0a31f9b5603fef@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000f52642060d4e3750@google.com
Signed-off-by: Penglei Jiang <superman.xpt@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Adrian Ratiu <adrian.ratiu@collabora.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Felix Moessbauer <felix.moessbauer@siemens.com>
Cc: Jeff layton <jlayton@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Replace `sr` with `Sr`. The condition `!tmp1 || rb_is_black(tmp1)`
ensures that `tmp1` (which is `sibling->rb_right`) is either NULL or a
black node. Therefore, the right child of the sibling must be black, and
the example should use `Sr` instead of `sr`.
Link: https://lkml.kernel.org/r/20250403112614.570140-1-johnny1001s000602@gmail.com
Signed-off-by: Chisheng Chen <johnny1001s000602@gmail.com>
Cc: Hsin Chang Yu <zxcvb600870024@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
On Intel TDX guest, unaccepted memory is unusable free memory which is not
managed by buddy, until it's accepted by guest. Before that, it cannot be
accessed by the first kernel as well as the kexec'ed kernel. The kexec'ed
kernel will skip these pages and fill in zero data for the reader of
vmcore.
The dump tool like makedumpfile creates a page descriptor (size 24 bytes)
for each non-free page, including zero data page, but it will not create
descriptor for free pages. If it is not able to distinguish these
unaccepted pages with zero data pages, a certain amount of space will be
wasted in proportion (~1/170). In fact, as a special kind of free page
the unaccepted pages should be excluded, like the real free pages.
Export the page type PAGE_UNACCEPTED_MAPCOUNT_VALUE to vmcoreinfo, so that
dump tool can identify whether a page is unaccepted.
[zhiquan1.li@intel.com: fix docs: "Title underline too short" warning]
Link: https://lore.kernel.org/all/20240809114854.3745464-5-kirill.shutemov@linux.intel.com/
Link: https://lkml.kernel.org/r/20250405060610.860465-1-zhiquan1.li@intel.com
Link: https://lore.kernel.org/all/20240809114854.3745464-5-kirill.shutemov@linux.intel.com/
Link: https://lkml.kernel.org/r/20250403030801.758687-1-zhiquan1.li@intel.com
Signed-off-by: Zhiquan Li <zhiquan1.li@intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Zhiquan Li <zhiquan1.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When initcall_debug is specified on the command line, the start and return
point for each initcall is printed. However, no information on the
initcall level is reported.
Add to the initcall_debug infrastructure an additional print that informs
when a new initcall level is entered. This is particularly useful when
debugging dependency chains and/or working on boot time reduction.
Link: https://lkml.kernel.org/r/20250316205014.2830071-2-francesco@valla.it
Signed-off-by: Francesco Valla <francesco@valla.it>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Bird <tim.bird@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
It is useful to be able to access current->mm at task exit to, say, record
a bunch of VMA information right before the task exits (e.g., for stack
symbolization reasons when dealing with short-lived processes that exit in
the middle of profiling session). Currently, trace_sched_process_exit()
is triggered after exit_mm() which resets current->mm to NULL making this
tracepoint unsuitable for inspecting and recording task's
mm_struct-related data when tracing process lifetimes.
There is a particularly suitable place, though, right after
taskstats_exit() is called, but before we do exit_mm() and other exit_*()
resource teardowns. taskstats performs a similar kind of accounting that
some applications do with BPF, and so co-locating them seems like a good
fit. So that's where trace_sched_process_exit() is moved with this patch.
Also, existing trace_sched_process_exit() tracepoint is notoriously
missing `group_dead` flag that is certainly useful in practice and some of
our production applications have to work around this. So plumb
`group_dead` through while at it, to have a richer and more complete
tracepoint.
Note that we can't use sched_process_template anymore, and so we use
TRACE_EVENT()-based tracepoint definition. But all the field names and
order, as well as assign and output logic remain intact. We just add one
extra field at the end in backwards-compatible way.
[andrii@kernel.org: document sched_process_exit and sched_process_template relation]
Link: https://lkml.kernel.org/r/20250403174120.4087794-1-andrii@kernel.org
Link: https://lkml.kernel.org/r/20250402180925.90914-1-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The weighted interleave policy distributes page allocations across
multiple NUMA nodes based on their performance weight, thereby improving
memory bandwidth utilization. The weight values for each node are
configured through sysfs.
Previously, sysfs entries for configuring weighted interleave were created
for all possible nodes (N_POSSIBLE) at initialization, including nodes
that might not have memory. However, not all nodes in N_POSSIBLE are
usable at runtime, as some may remain memoryless or offline. This led to
sysfs entries being created for unusable nodes, causing potential
misconfiguration issues.
To address this issue, this patch modifies the sysfs creation logic to:
1) Limit sysfs entries to nodes that are online and have memory, avoiding
the creation of sysfs entries for nodes that cannot be used.
2) Support memory hotplug by dynamically adding and removing sysfs entries
based on whether a node transitions into or out of the N_MEMORY state.
Additionally, the patch ensures that sysfs attributes are properly managed
when nodes go offline, preventing stale or redundant entries from
persisting in the system.
By making these changes, the weighted interleave policy now manages its
sysfs entries more efficiently, ensuring that only relevant nodes are
considered for interleaving, and dynamically adapting to memory hotplug
events.
[dan.carpenter@linaro.org: fix error code in sysfs_wi_node_add()]
Link: https://lkml.kernel.org/r/aBjL7Bwc0QBzgajK@stanley.mountain
Link: https://lkml.kernel.org/r/20250417072839.711-4-rakie.kim@sk.com
Co-developed-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Co-developed-by: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Previously, the weighted interleave sysfs structure was statically managed
during initialization. This prevented new nodes from being recognized
when memory hotplug events occurred, limiting the ability to update or
extend sysfs entries dynamically at runtime.
To address this, this patch refactors the sysfs infrastructure and
encapsulates it within a new structure, `sysfs_wi_group`, which holds both
the kobject and an array of node attribute pointers.
By allocating this group structure globally, the per-node sysfs attributes
can be managed beyond initialization time, enabling external modules to
insert or remove node entries in response to events such as memory hotplug
or node online/offline transitions.
Instead of allocating all per-node sysfs attributes at once, the
initialization path now uses the existing sysfs_wi_node_add() and
sysfs_wi_node_delete() helpers. This refactoring makes it possible to
modularly manage per-node sysfs entries and ensures the infrastructure is
ready for runtime extension.
Link: https://lkml.kernel.org/r/20250417072839.711-3-rakie.kim@sk.com
Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Enhance sysfs handling for memory hotplug in weighted
interleave", v9.
The following patch series enhances the weighted interleave policy in the
memory management subsystem by improving sysfs handling, fixing memory
leaks, and introducing dynamic sysfs updates for memory hotplug support.
This patch (of 3):
Memory leaks occurred when removing sysfs attributes for weighted
interleave. Improper kobject deallocation led to unreleased memory when
initialization failed or when nodes were removed.
The risk of leak is low because it only appears to trigger if setup
fails. Setup only fails due to -ENOMEM which is unlikely to happen
from a late_initcall() when memory pressure is low.
This patch resolves the issue by replacing unnecessary `kfree()` calls
with proper `kobject_del()` and `kobject_put()` sequences, ensuring
correct teardown and preventing memory leaks.
By explicitly calling `kobject_del()` before `kobject_put()`, the release
function is now invoked safely, and internal sysfs state is correctly
cleaned up. This guarantees that the memory associated with the kobject
is fully released and avoids resource leaks, thereby improving system
stability.
Additionally, sysfs_remove_file() is no longer called from the release
function to avoid accessing invalid sysfs state after kobject_del(). All
attribute removals are now done before kobject_del(), preventing WARN_ON()
in kernfs and ensuring safe and consistent cleanup of sysfs entries.
Link: https://lkml.kernel.org/r/20250417072839.711-1-rakie.kim@sk.com
Link: https://lkml.kernel.org/r/20250417072839.711-2-rakie.kim@sk.com
Fixes: dce41f5ae2 ("mm/mempolicy: implement the sysfs-based weighted_interleave interface")
Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently both atomics share one cache-line:
<snip>
...
ffffffff83eab400 b vmap_lazy_nr
ffffffff83eab408 b nr_vmalloc_pages
...
<snip>
those are global variables and they are only 8 bytes apart. Since they
are modified by different threads this causes a false sharing. This can
lead to a performance drop due to unnecessary cache invalidations.
After this patch it is aligned to a cache line boundary:
<snip>
...
ffffffff8260a600 d vmap_lazy_nr
ffffffff8260a640 d nr_vmalloc_pages
...
<snip>
Link: https://lkml.kernel.org/r/20250417161216.88318-4-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Adrian Huang <ahuang12@lenovo.com>
Tested-by: Adrian Huang <ahuang12@lenovo.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
A vmalloc subsystem includes "lib/test_vmalloc.c" test suite. Add an "F:"
entry under VMALLOC section to track this file as part of the subsystem.
Link: https://lkml.kernel.org/r/20250417161216.88318-3-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christop Hellwig <hch@infradead.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Remove the dependency on module loading ("m") for the vmalloc test suite,
enabling it to be built directly into the kernel, so both ("=m") and
("=y") are supported.
Motivation:
- Faster debugging/testing of vmalloc code;
- It allows to configure the test via kernel-boot parameters.
Configuration example:
test_vmalloc.nr_threads=64
test_vmalloc.run_test_mask=7
test_vmalloc.sequential_test_order=1
Link: https://lkml.kernel.org/r/20250417161216.88318-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Adrian Huang <ahuang12@lenovo.com>
Tested-by: Adrian Huang <ahuang12@lenovo.com>
Cc: Christop Hellwig <hch@infradead.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The test has the initialization step during which threads are created. To
prevent the workers from starting prematurely a write lock was previously
used by the main setup thread, while each worker would block on a read
lock.
Replace this RWSEM based synchronization with a simpler SRCU based
approach. Which does two basic steps:
- Main thread wraps the setup phase in an SRCU read-side critical
section. Pair of srcu_read_lock()/srcu_read_unlock().
- Each worker calls synchronize_srcu() on entry, ensuring it waits for
the initialization phase to be completed.
This patch eliminates the need for down_read()/up_read() and
down_write()/up_write() pairs thus simplifying the logic and improving
clarity.
[urezki@gmail.com: fix compile error with CONFIG_TINY_RCU]
Link: https://lkml.kernel.org/r/20250420142029.103169-1-urezki@gmail.com
Link: https://lkml.kernel.org/r/20250417161216.88318-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Adrian Huang <ahuang12@lenovo.com>
Tested-by: Adrian Huang <ahuang12@lenovo.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Christop Hellwig <hch@infradead.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Move IDLE pages tracking into a separate chapter because there are
multiple features that use (or depend on) it either in built-in variant
("mark all") or in extended variant (ac-time tracking).
In addition, recompression doesn't require memory tracking to be enabled
in order to be able to perform idle recompression.
Link: https://lkml.kernel.org/r/20250416042833.3858827-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reported-by: Shin Kawamura <kawasin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After the check for queue_folio_required(), the code only cares about the
folio in the for loop, i.e the PTEs are redundant. Therefore, optimize
this loop by skipping over a PTE batch mapping the same folio.
With a test program migrating pages of the calling process, which includes
a mapped VMA of size 4GB with pte-mapped large folios of order-9, and
migrating once back and forth node-0 and node-1, the average execution
time reduces from 7.5 to 4 seconds, giving an approx 47% speedup.
Link: https://lkml.kernel.org/r/20250416053048.96479-1-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently the VMA and mmap locking logic is entangled in two of the most
overwrought files in mm - include/linux/mm.h and mm/memory.c. Separate
this logic out so we can more easily make changes and create an
appropriate MAINTAINERS entry that spans only the logic relating to
locking.
This should have no functional change. Care is taken to avoid dependency
loops, we must regrettably keep release_fault_lock() and
assert_fault_locked() in mm.h as a result due to the dependence on the
vm_fault type.
Additionally we must declare rcuwait_wake_up() manually to avoid a
dependency cycle on linux/rcuwait.h.
Additionally move the nommu implementatino of lock_mm_and_find_vma() to
mmap_lock.c so everything lock-related is in one place.
Link: https://lkml.kernel.org/r/bec6c8e29fa8de9267a811a10b1bdae355d67ed4.1744799282.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Memory cgroup accounting is expensive and to reduce the cost, the kernel
maintains per-cpu charge cache for a single memcg. So, if a charge
request comes for a different memcg, the kernel will flush the old memcg's
charge cache and then charge the newer memcg a fixed amount (64 pages),
subtracts the charge request amount and stores the remaining in the
per-cpu charge cache for the newer memcg.
This mechanism is based on the assumption that the kernel, for locality,
keep a process on a CPU for long period of time and most of the charge
requests from that process will be served by that CPU's local charge
cache.
However this assumption breaks down for incoming network traffic in a
multi-tenant machine. We are in the process of running multiple workloads
on a single machine and if such workloads are network heavy, we are seeing
very high network memory accounting cost. We have observed multiple CPUs
spending almost 100% of their time in net_rx_action and almost all of that
time is spent in memcg accounting of the network traffic.
More precisely, net_rx_action is serving packets from multiple workloads
and is observing/serving mix of packets of these workloads. The memcg
switch of per-cpu cache is very expensive and we are observing a lot of
memcg switches on the machine. Almost all the time is being spent on
charging new memcg and flushing older memcg cache. So, definitely we need
per-cpu cache that support multiple memcgs for this scenario.
This patch implements a simple (and dumb) multiple memcg percpu charge
cache. Actually we started with more sophisticated LRU based approach but
the dumb one was always better than the sophisticated one by 1% to 3%, so
going with the simple approach.
Some of the design choices are:
1. Fit all caches memcgs in a single cacheline.
2. The cache array can be mix of empty slots or memcg charged slots, so
the kernel has to traverse the full array.
3. The cache drain from the reclaim will drain all cached memcgs to keep
things simple.
To evaluate the impact of this optimization, on a 72 CPUs machine, we ran
the following workload where each netperf client runs in a different
cgroup. The next-20250415 kernel is used as base.
$ netserver -6
$ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
number of clients | Without patch | With patch
6 | 42584.1 Mbps | 48603.4 Mbps (14.13% improvement)
12 | 30617.1 Mbps | 47919.7 Mbps (56.51% improvement)
18 | 25305.2 Mbps | 45497.3 Mbps (79.79% improvement)
24 | 20104.1 Mbps | 37907.7 Mbps (88.55% improvement)
30 | 14702.4 Mbps | 30746.5 Mbps (109.12% improvement)
36 | 10801.5 Mbps | 26476.3 Mbps (145.11% improvement)
The results show drastic improvement for network intensive workloads.
[shakeel.butt@linux.dev: add BUILD_BUG_ON() for MEMCG_CHARGE_BATCH]
Link: https://lkml.kernel.org/r/rlsgeosg3j7v5nihhbxxxbv3xfy4ejvigihj7lkkbt3n6imyne@2apxx2jm2e57
[shakeel.butt@linux.dev: simplify refill_stock]
Link: https://lkml.kernel.org/r/as5cdsm4lraxupg3t6onep2ixql72za25hvd4x334dsoyo4apr@zyzl4vkuevuv
[hughd@google.com: it's better to stock nr_pages than the uninitialized stock_pages]
Link: https://lkml.kernel.org/r/d542d18f-1caa-6fea-e2c3-3555c87bcf64@google.com
[shakeel.butt@linux.dev: add comment per Michal and use DEFINE_PER_CPU_ALIGNED instead of DEFINE_PER_CPU per Vlastimil]
Link: https://lkml.kernel.org/r/dieeei3squ2gcnqxdjayvxbvzldr266rhnvtl3vjzsqevxkevf@ckui5vjzl2qg
Link: https://lkml.kernel.org/r/20250416180229.2902751-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Eric Dumaze <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
free_page_and_swap_cache() takes a struct page pointer as input parameter,
but it will immediately convert it to folio and all operations following
within use folio instead of page. It makes more sense to pass in folio
directly.
Convert free_page_and_swap_cache() to free_folio_and_swap_cache() to
consume folio directly.
Link: https://lkml.kernel.org/r/20250416201720.41678-1-nifan.cxl@gmail.com
Signed-off-by: Fan Ni <fan.ni@samsung.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Adam Manzanares <a.manzanares@samsung.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
commit c928807f6f6b6("mm/page_alloc: keep track of free highatomic")
adds a new variable nr_free_highatomic, which is useful for analyzing low
mem issues. add nr_free_highatomic in show_free_areas.
Signed-off-by: gao xu <gaoxu2@honor.com>
Link: https://lkml.kernel.org/r/d92eeff74f7a4578a14ac777cfe3603a@honor.com
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The scan and total_scan variables can be initialized to 0 when they are
defined, replacing the separate assignment statements.
Link: https://lkml.kernel.org/r/20250417092422.1333620-1-hao.ge@linux.dev
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Acked-by: Dev Jain <dev.jain@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The code style in fault_in_readable() and fault_in_writable() is a little
inconsistent with fault_in_safe_writeable(). In fault_in_readable() and
fault_in_writable(), it uses 'uaddr' passed in as loop cursor. While in
fault_in_safe_writeable(), local variable 'start' is used as loop cursor.
This may mislead people when reading code or making change in these codes.
Here define explicit loop cursor and use for loop to simplify codes in
these three functions. These cleanup can make them be consistent in code
style and improve readability.
[bhe@redhat.com: address minor concerns from David]
Link: https://lkml.kernel.org/r/Z/sbv3EmLXWgEE7+@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20250410035717.473207-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yanjun.Zhu <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In the current kernel, only pud huge page is supported in some
architectures. P4d and pgd huge pages haven't been supported yet. And in
mm/gup.c, there's no pgd huge page handling in the follow_page_mask() code
path. Hence it doesn't make sense to only have gup_fast_pgd_leaf() in
gup_fast code path.
Here remove gup_fast_pgd_leaf() and clean up the relevant codes.
Link: https://lkml.kernel.org/r/20250410035717.473207-4-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Yanjun.Zhu <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/gup: Minor fix, cleanup and improvements", v4.
These were made from code inspection in mm/gup.c.
This patch (of 3):
In __get_user_pages(), it will traverse page table and take a reference to
the page the given user address corresponds to if GUP_GET or GUP_PIN is
set. However, it's not supported both GUP_GET and GUP_PIN are set. Even
though this check need be done, it should be done earlier, but not doing
it till entering into follow_page_pte() and failed.
Furthermore, this checking has been done in is_valid_gup_args() and all
external users of __get_user_pages() will call is_valid_gup_args() to
catch the illegal setting. We don't need to worry about internal users of
__get_user_pages() because the gup_flags are set by MM code correctly.
Here remove the checking in follow_page_pte(), and add VM_WARN_ON_ONCE()
to catch the possible exceptional setting just in case.
And also change the VM_BUG_ON to VM_WARN_ON_ONCE() for checking (!!pages
!= !!(gup_flags & (FOLL_GET | FOLL_PIN))) because the checking has been
done in is_valid_gup_args() for external users of __get_user_pages().
Link: https://lkml.kernel.org/r/20250410035717.473207-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20250410035717.473207-3-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Yanjun.Zhu <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
alloc_buddy_hugetlb_folio() allocates a rmappable folio, then strips the
rmappable part and freezes it. We can simplify all that by allocating
frozen pages directly.
Link: https://lkml.kernel.org/r/20250411132359.312708-1-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Before trying to allocate a page, gather_surplus_pages() sets up a
nodemask for the nodes we can allocate from, but instead of passing the
nodemask down the road to the page allocator, it iterates over the nodes
within that nodemask right there, meaning that the page allocator will
receive a preferred_nid and a null nodemask.
This is a problem when using a memory policy, because it might be that the
page allocator ends up using a node as a fallback which is not represented
in the policy.
Avoid that by passing the nodemask directly to the page allocator, so it
can filter out fallback nodes that are not part of the nodemask.
Link: https://lkml.kernel.org/r/20250415121503.376811-1-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently the kernel maintains the stats updates per-memcg which is needed
to implement stats flushing threshold. On the update side, the update is
added to the per-cpu per-memcg update of the given memcg and all of its
ancestors. However when the given memcg has passed the flushing
threshold, all of its ancestors should have passed the threshold as well.
There is no need to traverse up the memcg tree to maintain the stats
updates.
Perf profile collected from our fleet shows that memcg_rstat_updated is
one of the most expensive memcg function i.e. a lot of cumulative CPU is
being spent on it. So, even small micro optimizations matter a lot. This
patch is microbenchmarked with multiple instances of netperf on a single
machine with locally running netserver and we see couple of percentage of
improvement.
Link: https://lkml.kernel.org/r/20250410025752.92159-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
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>
During cleanup, the value of /proc/sys/vm/nr_hugepages is currently being
set to 0. At the end of the test, if all tests pass, the original
nr_hugepages value is restored. However, if any test fails, it remains
set to 0.
With this patch, we ensure that the original nr_hugepages value is
restored during cleanup, regardless of whether the test passes or fails.
Link: https://lkml.kernel.org/r/20250410100748.2310-1-donettom@linux.ibm.com
Fixes: 29750f71a9 ("hugetlb_cgroup: add hugetlb_cgroup reservation tests")
Signed-off-by: Donet Tom <donettom@linux.ibm.com>
Cc: Li Wang <liwang@redhat.com>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Move the unlikely case that mas->store_type is invalid to be the last
evaluated case and put liklier cases higher up.
Link: https://lkml.kernel.org/r/20250410191446.2474640-7-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: Liam R. Howlett <liam.howlett@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In order to support rebalancing and spanning stores using less than the
worst case number of nodes, we need to track more than just the vacant
height. Using only vacant height to reduce the worst case maple node
allocation count can lead to a shortcoming of nodes in the following
scenarios.
For rebalancing writes, when a leaf node becomes insufficient, it may be
combined with a sibling into a single node. This means that the parent
node which has entries for this children will lose one entry. If this
parent node was just meeting the minimum entries, losing one entry will
now cause this parent node to be insufficient. This leads to a cascading
operation of rebalancing at different levels and can lead to more node
allocations than simply using vacant height can return.
For spanning writes, a similar situation occurs. At the location at which
a spanning write is detected, the number of ancestor nodes may similarly
need to rebalanced into a smaller number of nodes and the same cascading
situation could occur.
To use less than the full height of the tree for the number of
allocations, we also need to track the height at which a non-leaf node
cannot become insufficient. This means even if a rebalance occurs to a
child of this node, it currently has enough entries that it can lose one
without any further action. This field is stored in the maple write state
as sufficient height. In mas_prealloc_calc() when figuring out how many
nodes to allocate, we check if the vacant node is lower in the tree than a
sufficient node (has a larger value). If it is, we cannot use the vacant
height and must use the difference in the height and sufficient height as
the basis for the number of nodes needed.
An off by one bug was also discovered in mast_overflow() where it is using
>= rather than >. This caused extra iterations of the
mas_spanning_rebalance() loop and lead to unneeded allocations. A test is
also added to check the number of allocations is correct.
Link: https://lkml.kernel.org/r/20250410191446.2474640-6-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This allows support for using the vacant height to calculate the worst
case number of nodes needed for wr_rebalance operation.
mas_spanning_rebalance() was seen to perform unnecessary node allocations.
We can reduce allocations by breaking early during the rebalancing loop
once we realize that we have ascended to a common ancestor.
Link: https://lkml.kernel.org/r/20250410191446.2474640-5-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: Liam Howlett <liam.howlett@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In order to determine the store type for a maple tree operation, a walk of
the tree is done through mas_wr_walk(). This function descends the tree
until a spanning write is detected or we reach a leaf node. While
descending, keep track of the height at which we encounter a node with
available space. This is done by checking if mas->end is less than the
number of slots a given node type can fit.
Now that the height of the vacant node is tracked, we can use the
difference between the height of the tree and the height of the vacant
node to know how many levels we will have to propagate creating new nodes.
Update mas_prealloc_calc() to consider the vacant height and reduce the
number of worst-case allocations.
Rebalancing and spanning stores are not supported and fall back to using
the full height of the tree for allocations.
Update preallocation testing assertions to take into account vacant
height.
Link: https://lkml.kernel.org/r/20250410191446.2474640-4-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
