License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 15:07:57 +01:00
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2009-05-05 19:13:44 +10:00
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2007-05-06 14:49:36 -07:00
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2012-07-06 15:25:11 -05:00
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2008-10-06 02:42:17 +04:00
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2007-05-06 14:49:36 -07:00
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2015-02-13 14:39:38 -08:00
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2007-05-06 14:49:36 -07:00
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2008-04-30 00:55:01 -07:00
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2007-05-06 14:49:36 -07:00
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2007-10-21 16:41:37 -07:00
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2008-05-01 04:34:31 -07:00
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2008-12-23 19:37:01 +09:00
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2011-07-07 22:47:01 +03:00
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2012-01-30 15:53:51 -06:00
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2012-12-18 14:22:34 -08:00
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2017-09-06 16:19:18 -07:00
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2007-05-06 14:49:36 -07:00
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2010-10-21 10:29:19 +01:00
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mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon. Swap over the network is considered as an option in diskless
systems. The two likely scenarios are when blade servers are used as part
of a cluster where the form factor or maintenance costs do not allow the
use of disks and thin clients.
The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap according to the manual at
https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download
There is also documentation and tutorials on how to setup swap over NBD at
places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The
nbd-client also documents the use of NBD as swap. Despite this, the fact
is that a machine using NBD for swap can deadlock within minutes if swap
is used intensively. This patch series addresses the problem.
The core issue is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need. Some years ago, Peter Zijlstra developed a series of
patches that supported swap over an NFS that at least one distribution is
carrying within their kernels. This patch series borrows very heavily
from Peter's work to support swapping over NBD as a pre-requisite to
supporting swap-over-NFS. The bulk of the complexity is concerned with
preserving memory that is allocated from the PFMEMALLOC reserves for use
by the network layer which is needed for both NBD and NFS.
Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeing memory.
Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required
Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 7-12 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean pages. If
packets are received and stored in pages that were allocated under
low-memory situations and are unrelated to the VM, the packets
are dropped.
Patch 11 reintroduces __skb_alloc_page which the networking
folk may object to but is needed in some cases to propogate
pfmemalloc from a newly allocated page to an skb. If there is a
strong objection, this patch can be dropped with the impact being
that swap-over-network will be slower in some cases but it should
not fail.
Patch 13 is a micro-optimisation to avoid a function call in the
common case.
Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 15 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get throttled on
a waitqueue if 50% of the PFMEMALLOC reserves are depleted. It is
expected that kswapd and the direct reclaimers already running
will clean enough pages for the low watermark to be reached and
the throttled processes are woken up.
Patch 16 adds a statistic to track how often processes get throttled
Some basic performance testing was run using kernel builds, netperf on
loopback for UDP and TCP, hackbench (pipes and sockets), iozone and
sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant performance
variances.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 8*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure.
Without the patches and using SLUB, the machine locks up within minutes
and runs to completion with them applied. With SLAB, the story is
different as an unpatched kernel run to completion. However, the patched
kernel completed the test 45% faster.
MICRO
3.5.0-rc2 3.5.0-rc2
vanilla swapnbd
Unrecognised test vmscan-anon-mmap-write
MMTests Statistics: duration
Sys Time Running Test (seconds) 197.80 173.07
User+Sys Time Running Test (seconds) 206.96 182.03
Total Elapsed Time (seconds) 3240.70 1762.09
This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
Allocations of pages below the min watermark run a risk of the machine
hanging due to a lack of memory. To prevent this, only callers who have
PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated to
a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
When this patch is applied, pages allocated from below the low watermark
are returned with page->pfmemalloc set and it is up to the caller to
determine how the page should be protected. SLAB restricts access to any
page with page->pfmemalloc set to callers which are known to able to
access the PFMEMALLOC reserve. If one is not available, an attempt is
made to allocate a new page rather than use a reserve. SLUB is a bit more
relaxed in that it only records if the current per-CPU page was allocated
from PFMEMALLOC reserve and uses another partial slab if the caller does
not have the necessary GFP or process flags. This was found to be
sufficient in tests to avoid hangs due to SLUB generally maintaining
smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators can fail
a slab allocation even though free objects are available because they are
being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
[sebastian@breakpoint.cc: Correct order of page flag clearing]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 16:43:58 -07:00
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2012-07-06 15:25:12 -05:00
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2007-05-06 14:49:36 -07:00
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2012-07-06 15:25:12 -05:00
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2012-07-06 15:25:12 -05:00
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2011-06-01 12:25:53 -05:00
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2018-06-07 17:08:46 -07:00
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2011-06-01 12:25:53 -05:00
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2018-06-07 17:08:46 -07:00
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2011-06-01 12:25:53 -05:00
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2019-05-13 17:16:28 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-16 22:10:53 -07:00
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2007-10-16 01:26:05 -07:00
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2007-05-10 03:15:16 -07:00
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2010-07-09 14:07:14 -05:00
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2007-05-16 22:10:56 -07:00
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2010-07-09 14:07:14 -05:00
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2007-05-16 22:10:56 -07:00
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2010-07-09 14:07:14 -05:00
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2007-05-16 22:10:56 -07:00
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2010-07-09 14:07:14 -05:00
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2007-05-16 22:10:56 -07:00
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2016-08-04 15:31:55 -07:00
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2016-03-15 14:55:12 -07:00
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2013-06-19 14:05:52 +09:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:49 -05:00
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2007-05-06 14:49:46 -07:00
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2007-12-21 14:37:37 -08:00
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2007-05-06 14:49:44 -07:00
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2007-05-06 14:49:46 -07:00
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2013-11-08 20:47:37 +08:00
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2007-05-06 14:49:46 -07:00
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2016-03-15 14:55:06 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2016-03-15 14:55:09 -07:00
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2009-07-07 00:14:14 -07:00
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2009-07-27 18:30:35 -07:00
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2009-07-07 00:14:14 -07:00
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2009-07-27 18:30:35 -07:00
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2009-07-07 00:14:14 -07:00
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2008-10-22 23:00:38 +04:00
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2011-06-01 12:25:45 -05:00
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2008-10-22 23:00:38 +04:00
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2007-05-06 14:49:36 -07:00
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2017-11-15 17:32:18 -08:00
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2017-11-15 17:32:21 -08:00
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2017-11-15 17:32:18 -08:00
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2017-11-15 17:32:21 -08:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:43 -07:00
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2011-07-07 11:36:36 -07:00
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2007-05-09 02:32:43 -07:00
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2008-08-19 20:43:25 +03:00
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2011-07-07 11:36:36 -07:00
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2007-05-09 02:32:43 -07:00
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2010-10-05 13:57:26 -05:00
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2007-05-06 14:49:36 -07:00
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slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2017-02-22 15:41:11 -08:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:24 -07:00
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slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2017-02-22 15:41:11 -08:00
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2007-05-06 14:49:36 -07:00
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2011-03-22 13:35:00 -05:00
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2008-02-07 17:47:41 -08:00
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2014-04-07 15:39:42 -07:00
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2008-02-07 17:47:41 -08:00
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2007-05-06 14:49:36 -07:00
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2017-09-06 16:19:18 -07:00
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2019-02-20 22:19:32 -08:00
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2017-09-06 16:19:18 -07:00
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2007-05-09 02:32:40 -07:00
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2017-09-06 16:19:18 -07:00
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2007-05-09 02:32:40 -07:00
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slub: prefetch next freelist pointer in slab_alloc()
Recycling a page is a problem, since freelist link chain is hot on
cpu(s) which freed objects, and possibly very cold on cpu currently
owning slab.
Adding a prefetch of cache line containing the pointer to next object in
slab_alloc() helps a lot in many workloads, in particular on assymetric
ones (allocations done on one cpu, frees on another cpus). Added cost is
three machine instructions only.
Examples on my dual socket quad core ht machine (Intel CPU E5540
@2.53GHz) (16 logical cpus, 2 memory nodes), 64bit kernel.
Before patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
327577,471718 task-clock # 15,821 CPUs utilized ( +- 0,64% )
28 866 491 context-switches # 0,088 M/sec ( +- 1,80% )
1 506 929 CPU-migrations # 0,005 M/sec ( +- 3,24% )
127 151 page-faults # 0,000 M/sec ( +- 0,16% )
829 399 813 448 cycles # 2,532 GHz ( +- 0,64% )
580 664 691 740 stalled-cycles-frontend # 70,01% frontend cycles idle ( +- 0,71% )
197 431 700 448 stalled-cycles-backend # 23,80% backend cycles idle ( +- 1,03% )
503 548 648 975 instructions # 0,61 insns per cycle
# 1,15 stalled cycles per insn ( +- 0,46% )
95 780 068 471 branches # 292,389 M/sec ( +- 0,48% )
1 426 407 916 branch-misses # 1,49% of all branches ( +- 1,35% )
20,705679994 seconds time elapsed ( +- 0,64% )
After patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
286236,542804 task-clock # 15,786 CPUs utilized ( +- 1,32% )
19 703 372 context-switches # 0,069 M/sec ( +- 4,99% )
1 658 249 CPU-migrations # 0,006 M/sec ( +- 6,62% )
126 776 page-faults # 0,000 M/sec ( +- 0,12% )
724 636 593 213 cycles # 2,532 GHz ( +- 1,32% )
499 320 714 837 stalled-cycles-frontend # 68,91% frontend cycles idle ( +- 1,47% )
156 555 126 809 stalled-cycles-backend # 21,60% backend cycles idle ( +- 2,22% )
463 897 792 661 instructions # 0,64 insns per cycle
# 1,08 stalled cycles per insn ( +- 0,94% )
87 717 352 563 branches # 306,451 M/sec ( +- 0,99% )
941 738 280 branch-misses # 1,07% of all branches ( +- 3,35% )
18,132070670 seconds time elapsed ( +- 1,30% )
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Matt Mackall <mpm@selenic.com>
CC: David Rientjes <rientjes@google.com>
CC: "Alex,Shi" <alex.shi@intel.com>
CC: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-12-16 16:25:34 +01:00
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2018-08-17 15:44:44 -07:00
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|
|
slub: prefetch next freelist pointer in slab_alloc()
Recycling a page is a problem, since freelist link chain is hot on
cpu(s) which freed objects, and possibly very cold on cpu currently
owning slab.
Adding a prefetch of cache line containing the pointer to next object in
slab_alloc() helps a lot in many workloads, in particular on assymetric
ones (allocations done on one cpu, frees on another cpus). Added cost is
three machine instructions only.
Examples on my dual socket quad core ht machine (Intel CPU E5540
@2.53GHz) (16 logical cpus, 2 memory nodes), 64bit kernel.
Before patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
327577,471718 task-clock # 15,821 CPUs utilized ( +- 0,64% )
28 866 491 context-switches # 0,088 M/sec ( +- 1,80% )
1 506 929 CPU-migrations # 0,005 M/sec ( +- 3,24% )
127 151 page-faults # 0,000 M/sec ( +- 0,16% )
829 399 813 448 cycles # 2,532 GHz ( +- 0,64% )
580 664 691 740 stalled-cycles-frontend # 70,01% frontend cycles idle ( +- 0,71% )
197 431 700 448 stalled-cycles-backend # 23,80% backend cycles idle ( +- 1,03% )
503 548 648 975 instructions # 0,61 insns per cycle
# 1,15 stalled cycles per insn ( +- 0,46% )
95 780 068 471 branches # 292,389 M/sec ( +- 0,48% )
1 426 407 916 branch-misses # 1,49% of all branches ( +- 1,35% )
20,705679994 seconds time elapsed ( +- 0,64% )
After patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
286236,542804 task-clock # 15,786 CPUs utilized ( +- 1,32% )
19 703 372 context-switches # 0,069 M/sec ( +- 4,99% )
1 658 249 CPU-migrations # 0,006 M/sec ( +- 6,62% )
126 776 page-faults # 0,000 M/sec ( +- 0,12% )
724 636 593 213 cycles # 2,532 GHz ( +- 1,32% )
499 320 714 837 stalled-cycles-frontend # 68,91% frontend cycles idle ( +- 1,47% )
156 555 126 809 stalled-cycles-backend # 21,60% backend cycles idle ( +- 2,22% )
463 897 792 661 instructions # 0,64 insns per cycle
# 1,08 stalled cycles per insn ( +- 0,94% )
87 717 352 563 branches # 306,451 M/sec ( +- 0,99% )
941 738 280 branch-misses # 1,07% of all branches ( +- 3,35% )
18,132070670 seconds time elapsed ( +- 1,30% )
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Matt Mackall <mpm@selenic.com>
CC: David Rientjes <rientjes@google.com>
CC: "Alex,Shi" <alex.shi@intel.com>
CC: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-12-16 16:25:34 +01:00
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2011-05-16 15:26:08 -05:00
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2017-09-06 16:19:18 -07:00
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2011-05-16 15:26:08 -05:00
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2016-03-17 14:17:53 -07:00
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2017-09-06 16:19:18 -07:00
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2011-05-16 15:26:08 -05:00
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2007-05-09 02:32:40 -07:00
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2017-09-06 16:19:18 -07:00
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2017-09-06 16:19:22 -07:00
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2017-09-06 16:19:18 -07:00
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2007-05-09 02:32:40 -07:00
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2008-04-14 19:11:31 +03:00
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2016-03-15 14:55:12 -07:00
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2007-05-09 02:32:40 -07:00
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2018-04-05 16:21:35 -07:00
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2007-05-09 02:32:40 -07:00
|
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|
slub: fix a crash with SLUB_DEBUG + KASAN_SW_TAGS
In process_slab(), "p = get_freepointer()" could return a tagged
pointer, but "addr = page_address()" always return a native pointer. As
the result, slab_index() is messed up here,
return (p - addr) / s->size;
All other callers of slab_index() have the same situation where "addr"
is from page_address(), so just need to untag "p".
# cat /sys/kernel/slab/hugetlbfs_inode_cache/alloc_calls
Unable to handle kernel paging request at virtual address 2bff808aa4856d48
Mem abort info:
ESR = 0x96000007
Exception class = DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000007
CM = 0, WnR = 0
swapper pgtable: 64k pages, 48-bit VAs, pgdp = 0000000002498338
[2bff808aa4856d48] pgd=00000097fcfd0003, pud=00000097fcfd0003, pmd=00000097fca30003, pte=00e8008b24850712
Internal error: Oops: 96000007 [#1] SMP
CPU: 3 PID: 79210 Comm: read_all Tainted: G L 5.0.0-rc7+ #84
Hardware name: HPE Apollo 70 /C01_APACHE_MB , BIOS L50_5.13_1.0.6 07/10/2018
pstate: 00400089 (nzcv daIf +PAN -UAO)
pc : get_map+0x78/0xec
lr : get_map+0xa0/0xec
sp : aeff808989e3f8e0
x29: aeff808989e3f940 x28: ffff800826200000
x27: ffff100012d47000 x26: 9700000000002500
x25: 0000000000000001 x24: 52ff8008200131f8
x23: 52ff8008200130a0 x22: 52ff800820013098
x21: ffff800826200000 x20: ffff100013172ba0
x19: 2bff808a8971bc00 x18: ffff1000148f5538
x17: 000000000000001b x16: 00000000000000ff
x15: ffff1000148f5000 x14: 00000000000000d2
x13: 0000000000000001 x12: 0000000000000000
x11: 0000000020000002 x10: 2bff808aa4856d48
x9 : 0000020000000000 x8 : 68ff80082620ebb0
x7 : 0000000000000000 x6 : ffff1000105da1dc
x5 : 0000000000000000 x4 : 0000000000000000
x3 : 0000000000000010 x2 : 2bff808a8971bc00
x1 : ffff7fe002098800 x0 : ffff80082620ceb0
Process read_all (pid: 79210, stack limit = 0x00000000f65b9361)
Call trace:
get_map+0x78/0xec
process_slab+0x7c/0x47c
list_locations+0xb0/0x3c8
alloc_calls_show+0x34/0x40
slab_attr_show+0x34/0x48
sysfs_kf_seq_show+0x2e4/0x570
kernfs_seq_show+0x12c/0x1a0
seq_read+0x48c/0xf84
kernfs_fop_read+0xd4/0x448
__vfs_read+0x94/0x5d4
vfs_read+0xcc/0x194
ksys_read+0x6c/0xe8
__arm64_sys_read+0x68/0xb0
el0_svc_handler+0x230/0x3bc
el0_svc+0x8/0xc
Code: d3467d2a 9ac92329 8b0a0e6a f9800151 (c85f7d4b)
---[ end trace a383a9a44ff13176 ]---
Kernel panic - not syncing: Fatal exception
SMP: stopping secondary CPUs
SMP: failed to stop secondary CPUs 1-7,32,40,127
Kernel Offset: disabled
CPU features: 0x002,20000c18
Memory Limit: none
---[ end Kernel panic - not syncing: Fatal exception ]---
Link: http://lkml.kernel.org/r/20190220020251.82039-1-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-02-20 22:20:37 -08:00
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2007-05-09 02:32:40 -07:00
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2018-06-07 17:09:10 -07:00
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2011-03-10 15:21:48 +08:00
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2018-06-07 17:09:10 -07:00
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2011-03-10 15:21:48 +08:00
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2018-04-05 16:21:39 -07:00
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2018-06-07 17:09:10 -07:00
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2008-04-14 19:11:31 +03:00
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2018-06-07 17:09:10 -07:00
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2008-04-14 19:11:31 +03:00
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2018-04-05 16:21:39 -07:00
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2008-04-14 19:11:31 +03:00
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2008-10-22 23:00:38 +04:00
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2008-04-14 19:11:31 +03:00
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2018-04-05 16:21:39 -07:00
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2008-04-14 19:11:31 +03:00
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2008-10-22 23:00:38 +04:00
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2008-04-14 19:11:31 +03:00
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2011-06-01 12:25:53 -05:00
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2016-01-15 16:51:24 -08:00
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2011-06-01 12:25:53 -05:00
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2016-01-15 16:51:24 -08:00
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2011-06-01 12:25:53 -05:00
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2011-07-14 12:49:12 -05:00
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2011-06-01 12:25:49 -05:00
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2011-07-14 12:49:12 -05:00
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2012-01-12 17:17:33 -08:00
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2011-06-01 12:25:49 -05:00
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2012-01-02 17:02:18 +00:00
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2014-08-06 16:04:48 -07:00
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2015-04-14 15:44:31 -07:00
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2011-06-01 12:25:49 -05:00
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2011-06-01 12:25:53 -05:00
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2013-07-15 09:05:29 +08:00
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2011-06-01 12:25:49 -05:00
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2018-06-07 17:08:31 -07:00
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2011-06-01 12:25:53 -05:00
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2015-04-14 15:44:31 -07:00
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2011-06-01 12:25:49 -05:00
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2011-06-01 12:25:53 -05:00
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2011-06-01 12:25:49 -05:00
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2014-06-04 16:06:34 -07:00
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2011-06-01 12:25:49 -05:00
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2015-04-14 15:44:31 -07:00
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2011-06-01 12:25:49 -05:00
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2011-07-14 12:49:12 -05:00
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2012-01-12 17:17:33 -08:00
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2011-07-14 12:49:12 -05:00
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2012-01-02 17:02:18 +00:00
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2014-08-06 16:04:48 -07:00
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2015-04-14 15:44:31 -07:00
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2011-07-14 12:49:12 -05:00
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2013-07-15 09:05:29 +08:00
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2011-07-14 12:49:12 -05:00
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2018-06-07 17:08:31 -07:00
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2011-07-14 12:49:12 -05:00
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2015-04-14 15:44:31 -07:00
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2011-07-14 12:49:12 -05:00
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2014-06-04 16:06:34 -07:00
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2011-07-14 12:49:12 -05:00
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2015-04-14 15:44:31 -07:00
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2011-07-14 12:49:12 -05:00
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2007-05-09 02:32:44 -07:00
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2011-04-15 14:48:13 -05:00
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2011-06-01 12:25:53 -05:00
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2011-04-15 14:48:13 -05:00
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2018-04-05 16:21:43 -07:00
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2016-03-15 14:55:12 -07:00
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2007-05-09 02:32:44 -07:00
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2015-11-05 18:51:23 -08:00
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2017-11-15 17:32:18 -08:00
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2007-07-15 23:38:14 -07:00
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2017-11-15 17:32:18 -08:00
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2007-07-15 23:38:14 -07:00
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2007-05-09 02:32:44 -07:00
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2009-07-07 00:14:14 -07:00
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2007-05-09 02:32:44 -07:00
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2015-02-13 14:39:38 -08:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:12 -07:00
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2019-02-20 22:19:36 -08:00
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2016-03-15 14:55:12 -07:00
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2017-01-24 15:18:02 -08:00
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2007-05-06 14:49:36 -07:00
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2015-02-13 14:39:38 -08:00
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2017-01-24 15:18:02 -08:00
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2011-07-29 14:10:20 +02:00
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2015-02-13 14:39:38 -08:00
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2007-05-06 14:49:36 -07:00
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2008-08-19 20:43:25 +03:00
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2007-05-06 14:49:36 -07:00
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2009-03-07 00:36:21 +09:00
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2007-05-06 14:49:36 -07:00
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2011-07-07 11:36:36 -07:00
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2019-04-25 11:45:00 +02:00
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2011-07-07 11:36:36 -07:00
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2015-02-13 14:39:38 -08:00
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2019-04-25 11:45:00 +02:00
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2015-02-13 14:39:38 -08:00
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2011-07-07 11:36:36 -07:00
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2019-04-25 11:45:00 +02:00
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2011-07-07 11:36:36 -07:00
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2007-05-06 14:49:36 -07:00
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2008-06-23 02:58:37 +04:00
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2007-05-06 14:49:36 -07:00
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2019-04-10 12:28:05 +02:00
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2007-05-06 14:49:36 -07:00
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2019-04-10 12:28:05 +02:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2008-08-19 20:43:25 +03:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:20:15 -07:00
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2007-05-06 14:49:36 -07:00
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2014-06-04 16:06:34 -07:00
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2018-04-05 16:20:15 -07:00
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2011-07-07 11:36:36 -07:00
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2014-06-04 16:06:34 -07:00
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2011-07-07 11:36:36 -07:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2018-04-05 16:20:15 -07:00
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2007-07-17 04:03:18 -07:00
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2018-04-05 16:20:15 -07:00
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2007-07-17 04:03:18 -07:00
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2014-06-04 16:06:34 -07:00
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2013-07-15 09:05:29 +08:00
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2007-07-17 04:03:18 -07:00
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2014-06-04 16:06:35 -07:00
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2007-07-17 04:03:18 -07:00
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2014-06-04 16:06:35 -07:00
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2014-06-04 16:06:34 -07:00
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2014-06-04 16:06:35 -07:00
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2014-06-04 16:06:34 -07:00
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2012-09-18 15:54:12 -04:00
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2013-01-21 17:17:39 +10:30
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2014-06-04 16:06:35 -07:00
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2007-07-17 04:03:18 -07:00
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2014-06-04 16:06:35 -07:00
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2007-07-17 04:03:18 -07:00
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2014-06-04 16:06:35 -07:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2008-03-01 13:40:44 -08:00
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2007-07-17 04:03:18 -07:00
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2014-06-04 16:06:34 -07:00
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2007-07-17 04:03:18 -07:00
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2016-03-15 14:55:12 -07:00
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2017-01-24 15:18:02 -08:00
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2016-03-15 14:55:12 -07:00
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2017-01-24 15:18:02 -08:00
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2007-05-06 14:49:36 -07:00
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2017-01-24 15:18:02 -08:00
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2018-04-05 16:21:17 -07:00
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2007-05-06 14:49:36 -07:00
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2017-01-24 15:18:02 -08:00
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2012-06-13 10:24:57 -05:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2016-07-28 15:49:07 -07:00
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2016-03-15 14:55:12 -07:00
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2007-05-06 14:49:36 -07:00
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2017-01-24 15:18:02 -08:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2015-02-13 14:39:35 -08:00
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2007-05-06 14:49:36 -07:00
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2008-04-23 12:28:01 -07:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2018-06-07 17:05:17 -07:00
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2013-07-15 09:05:29 +08:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-23 12:28:01 -07:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2010-09-29 07:15:01 -05:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:12 -07:00
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2007-05-06 14:49:36 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-06 14:49:36 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2008-01-07 23:20:27 -08:00
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2007-07-17 04:03:18 -07:00
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2015-02-13 14:39:38 -08:00
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2011-10-31 17:08:07 -07:00
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2015-02-13 14:39:38 -08:00
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2007-07-17 04:03:18 -07:00
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2014-06-04 16:06:34 -07:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2008-02-15 23:45:26 -08:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2016-07-28 15:49:07 -07:00
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2016-03-15 14:55:12 -07:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2016-03-15 14:55:12 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:30 +03:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2018-01-31 16:15:43 -08:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2008-03-01 13:40:44 -08:00
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2018-06-07 17:09:10 -07:00
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2008-04-14 19:11:30 +03:00
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2007-05-06 14:49:36 -07:00
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2018-01-31 16:15:43 -08:00
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2015-02-13 14:39:38 -08:00
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2018-01-31 16:15:43 -08:00
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2015-02-13 14:39:38 -08:00
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2007-07-17 04:03:18 -07:00
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2018-01-31 16:15:43 -08:00
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2007-07-17 04:03:18 -07:00
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2018-01-31 16:15:43 -08:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2010-09-29 07:15:01 -05:00
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2007-05-06 14:49:36 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:12 -07:00
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2007-07-17 04:03:18 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-06 14:49:36 -07:00
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2012-06-13 10:24:57 -05:00
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2008-02-05 17:57:39 -08:00
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2013-07-15 09:05:29 +08:00
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2008-02-05 17:57:39 -08:00
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2007-05-06 14:49:36 -07:00
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2010-09-29 07:15:01 -05:00
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2007-07-17 04:03:18 -07:00
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2012-06-13 10:24:57 -05:00
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2007-07-17 04:03:18 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-06 14:49:36 -07:00
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2010-09-29 07:15:01 -05:00
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2007-05-06 14:49:36 -07:00
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2008-12-05 14:08:08 +11:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2008-03-01 13:40:44 -08:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:30 +03:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:30 +03:00
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2018-06-07 17:09:10 -07:00
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2008-04-14 19:11:30 +03:00
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mm: slub: fix format mismatches in slab_err() callers
Adding __printf(3, 4) to slab_err exposed following:
mm/slub.c: In function `check_slab':
mm/slub.c:852:4: warning: format `%u' expects argument of type `unsigned int', but argument 4 has type `const char *' [-Wformat=]
s->name, page->objects, maxobj);
^
mm/slub.c:852:4: warning: too many arguments for format [-Wformat-extra-args]
mm/slub.c:857:4: warning: format `%u' expects argument of type `unsigned int', but argument 4 has type `const char *' [-Wformat=]
s->name, page->inuse, page->objects);
^
mm/slub.c:857:4: warning: too many arguments for format [-Wformat-extra-args]
mm/slub.c: In function `on_freelist':
mm/slub.c:905:4: warning: format `%d' expects argument of type `int', but argument 5 has type `long unsigned int' [-Wformat=]
"should be %d", page->objects, max_objects);
Fix first two warnings by removing redundant s->name.
Fix the last by changing type of max_object from unsigned long to int.
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-10 15:42:22 -08:00
|
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2008-04-14 19:11:30 +03:00
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2007-07-17 04:03:18 -07:00
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|
mm: slub: fix format mismatches in slab_err() callers
Adding __printf(3, 4) to slab_err exposed following:
mm/slub.c: In function `check_slab':
mm/slub.c:852:4: warning: format `%u' expects argument of type `unsigned int', but argument 4 has type `const char *' [-Wformat=]
s->name, page->objects, maxobj);
^
mm/slub.c:852:4: warning: too many arguments for format [-Wformat-extra-args]
mm/slub.c:857:4: warning: format `%u' expects argument of type `unsigned int', but argument 4 has type `const char *' [-Wformat=]
s->name, page->inuse, page->objects);
^
mm/slub.c:857:4: warning: too many arguments for format [-Wformat-extra-args]
mm/slub.c: In function `on_freelist':
mm/slub.c:905:4: warning: format `%d' expects argument of type `int', but argument 5 has type `long unsigned int' [-Wformat=]
"should be %d", page->objects, max_objects);
Fix first two warnings by removing redundant s->name.
Fix the last by changing type of max_object from unsigned long to int.
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-10 15:42:22 -08:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:53 -05:00
|
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|
|
2007-05-06 14:49:36 -07:00
|
|
|
|
mm: slub: fix format mismatches in slab_err() callers
Adding __printf(3, 4) to slab_err exposed following:
mm/slub.c: In function `check_slab':
mm/slub.c:852:4: warning: format `%u' expects argument of type `unsigned int', but argument 4 has type `const char *' [-Wformat=]
s->name, page->objects, maxobj);
^
mm/slub.c:852:4: warning: too many arguments for format [-Wformat-extra-args]
mm/slub.c:857:4: warning: format `%u' expects argument of type `unsigned int', but argument 4 has type `const char *' [-Wformat=]
s->name, page->inuse, page->objects);
^
mm/slub.c:857:4: warning: too many arguments for format [-Wformat-extra-args]
mm/slub.c: In function `on_freelist':
mm/slub.c:905:4: warning: format `%d' expects argument of type `int', but argument 5 has type `long unsigned int' [-Wformat=]
"should be %d", page->objects, max_objects);
Fix first two warnings by removing redundant s->name.
Fix the last by changing type of max_object from unsigned long to int.
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-10 15:42:22 -08:00
|
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:53 -05:00
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2008-04-14 19:11:30 +03:00
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2007-05-06 14:49:36 -07:00
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2008-03-01 13:40:44 -08:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2008-03-01 13:40:44 -08:00
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2008-04-14 19:11:30 +03:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2018-06-07 17:09:10 -07:00
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2008-10-22 23:00:38 +04:00
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2008-04-14 19:11:31 +03:00
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2016-03-17 14:19:47 -07:00
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2008-04-14 19:11:31 +03:00
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2008-04-14 19:11:30 +03:00
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2016-03-17 14:19:47 -07:00
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2008-04-14 19:11:30 +03:00
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2007-07-17 04:03:18 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-29 16:11:12 -07:00
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2007-05-16 22:11:00 -07:00
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2014-06-04 16:06:34 -07:00
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2007-05-16 22:11:00 -07:00
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2017-01-24 15:18:02 -08:00
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2013-07-15 09:05:29 +08:00
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2007-05-16 22:11:00 -07:00
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2007-05-06 14:49:42 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:42 -07:00
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2011-06-01 12:25:50 -05:00
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2007-05-06 14:49:42 -07:00
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2014-02-10 14:25:39 -08:00
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2019-05-13 17:16:12 -07:00
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2011-06-01 12:25:50 -05:00
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2014-01-10 13:23:49 +01:00
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2011-06-01 12:25:50 -05:00
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2007-05-06 14:49:42 -07:00
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2014-02-10 14:25:39 -08:00
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2019-05-13 17:16:12 -07:00
|
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2007-05-06 14:49:42 -07:00
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2008-04-14 18:53:02 +03:00
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2009-06-11 14:08:48 +04:00
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2008-04-14 19:11:40 +03:00
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2008-04-14 18:53:02 +03:00
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2013-01-21 17:01:27 +09:00
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2008-04-14 18:53:02 +03:00
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2008-04-14 19:11:40 +03:00
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2008-04-14 18:53:02 +03:00
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2008-04-14 19:11:40 +03:00
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2008-04-14 18:53:02 +03:00
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2008-04-14 19:11:40 +03:00
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2008-04-14 18:53:02 +03:00
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2007-05-16 22:11:00 -07:00
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2010-09-29 07:15:01 -05:00
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2007-05-16 22:11:00 -07:00
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2019-02-20 22:19:23 -08:00
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2016-03-15 14:55:06 -07:00
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2019-03-05 15:42:10 -08:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:06 -07:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:06 -07:00
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2007-05-06 14:49:36 -07:00
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2010-09-29 07:15:01 -05:00
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2016-03-15 14:55:06 -07:00
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2019-03-05 15:42:10 -08:00
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2016-03-15 14:55:06 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-16 22:11:00 -07:00
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2010-09-29 07:15:01 -05:00
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2007-05-06 14:49:36 -07:00
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2007-05-16 22:11:00 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:18 -07:00
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2008-04-14 19:11:30 +03:00
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2008-03-01 13:40:44 -08:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:06 -07:00
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2016-03-17 14:19:47 -07:00
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2016-03-15 14:55:06 -07:00
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2015-11-20 15:57:46 -08:00
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2016-03-15 14:54:59 -07:00
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2015-11-20 15:57:46 -08:00
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2016-03-15 14:54:59 -07:00
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2007-05-06 14:49:36 -07:00
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2012-05-30 12:54:46 -05:00
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2015-11-20 15:57:46 -08:00
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2016-03-15 14:54:59 -07:00
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2016-03-15 14:55:02 -07:00
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2011-06-01 12:25:54 -05:00
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2016-03-15 14:54:59 -07:00
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2011-06-01 12:25:53 -05:00
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2016-03-15 14:55:06 -07:00
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2007-05-06 14:49:36 -07:00
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2015-11-20 15:57:46 -08:00
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2016-03-15 14:55:06 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-16 22:11:00 -07:00
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2015-11-20 15:57:46 -08:00
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2010-09-29 07:15:01 -05:00
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2015-11-20 15:57:46 -08:00
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2016-03-15 14:55:02 -07:00
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2011-06-01 12:25:54 -05:00
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2015-11-20 15:57:46 -08:00
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2011-06-01 12:25:53 -05:00
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2016-03-15 14:54:59 -07:00
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2016-03-15 14:55:02 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:44 -07:00
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2007-07-15 23:38:14 -07:00
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2007-05-09 02:32:44 -07:00
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2007-07-15 23:38:14 -07:00
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2008-01-07 23:20:27 -08:00
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2007-07-15 23:38:14 -07:00
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2016-03-15 14:55:06 -07:00
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2007-07-15 23:38:14 -07:00
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2010-02-26 09:36:12 +03:00
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2015-04-14 15:44:25 -07:00
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2007-07-15 23:38:14 -07:00
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2014-06-04 16:06:34 -07:00
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2007-07-15 23:38:14 -07:00
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2007-05-09 02:32:44 -07:00
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2007-07-15 23:38:14 -07:00
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mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
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2007-05-09 02:32:44 -07:00
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2018-10-26 15:03:15 -07:00
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2018-04-05 16:21:24 -07:00
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2017-11-15 17:32:18 -08:00
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2008-07-25 19:45:34 -07:00
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2007-05-09 02:32:44 -07:00
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2018-10-26 15:03:15 -07:00
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2019-07-11 20:53:33 -07:00
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2018-10-26 15:03:15 -07:00
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2007-09-11 15:24:11 -07:00
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2007-05-09 02:32:44 -07:00
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2015-11-20 15:57:41 -08:00
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2007-05-16 22:11:00 -07:00
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2019-02-20 22:19:23 -08:00
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2007-05-09 02:32:44 -07:00
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2007-05-16 22:11:00 -07:00
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2008-08-19 20:43:25 +03:00
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2007-05-09 02:32:44 -07:00
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2016-03-15 14:54:59 -07:00
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2015-11-20 15:57:46 -08:00
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2016-03-15 14:54:59 -07:00
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2007-05-09 02:32:44 -07:00
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2010-09-29 07:15:01 -05:00
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2011-06-01 12:25:50 -05:00
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2014-01-10 13:23:49 +01:00
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2018-04-05 16:21:24 -07:00
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2017-11-15 17:32:18 -08:00
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2008-07-25 19:45:34 -07:00
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2007-09-11 15:24:11 -07:00
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2007-05-09 02:32:44 -07:00
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2008-04-14 18:53:02 +03:00
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2009-09-15 11:00:26 +02:00
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2008-04-14 18:53:02 +03:00
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2009-06-11 14:08:48 +04:00
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2008-04-14 19:11:40 +03:00
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2010-08-25 14:07:16 -05:00
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2014-08-06 16:04:18 -07:00
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kasan, mm: change hooks signatures
Patch series "kasan: add software tag-based mode for arm64", v13.
This patchset adds a new software tag-based mode to KASAN [1]. (Initially
this mode was called KHWASAN, but it got renamed, see the naming rationale
at the end of this section).
The plan is to implement HWASan [2] for the kernel with the incentive,
that it's going to have comparable to KASAN performance, but in the same
time consume much less memory, trading that off for somewhat imprecise bug
detection and being supported only for arm64.
The underlying ideas of the approach used by software tag-based KASAN are:
1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store
pointer tags in the top byte of each kernel pointer.
2. Using shadow memory, we can store memory tags for each chunk of kernel
memory.
3. On each memory allocation, we can generate a random tag, embed it into
the returned pointer and set the memory tags that correspond to this
chunk of memory to the same value.
4. By using compiler instrumentation, before each memory access we can add
a check that the pointer tag matches the tag of the memory that is being
accessed.
5. On a tag mismatch we report an error.
With this patchset the existing KASAN mode gets renamed to generic KASAN,
with the word "generic" meaning that the implementation can be supported
by any architecture as it is purely software.
The new mode this patchset adds is called software tag-based KASAN. The
word "tag-based" refers to the fact that this mode uses tags embedded into
the top byte of kernel pointers and the TBI arm64 CPU feature that allows
to dereference such pointers. The word "software" here means that shadow
memory manipulation and tag checking on pointer dereference is done in
software. As it is the only tag-based implementation right now, "software
tag-based" KASAN is sometimes referred to as simply "tag-based" in this
patchset.
A potential expansion of this mode is a hardware tag-based mode, which
would use hardware memory tagging support (announced by Arm [3]) instead
of compiler instrumentation and manual shadow memory manipulation.
Same as generic KASAN, software tag-based KASAN is strictly a debugging
feature.
[1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html
[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a
====== Rationale
On mobile devices generic KASAN's memory usage is significant problem.
One of the main reasons to have tag-based KASAN is to be able to perform a
similar set of checks as the generic one does, but with lower memory
requirements.
Comment from Vishwath Mohan <vishwath@google.com>:
I don't have data on-hand, but anecdotally both ASAN and KASAN have proven
problematic to enable for environments that don't tolerate the increased
memory pressure well. This includes
(a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go,
(c) Connected components like Pixel's visual core [1].
These are both places I'd love to have a low(er) memory footprint option at
my disposal.
Comment from Evgenii Stepanov <eugenis@google.com>:
Looking at a live Android device under load, slab (according to
/proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's
overhead of 2x - 3x on top of it is not insignificant.
Not having this overhead enables near-production use - ex. running
KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do
not reproduce in test configuration. These are the ones that often cost
the most engineering time to track down.
CPU overhead is bad, but generally tolerable. RAM is critical, in our
experience. Once it gets low enough, OOM-killer makes your life
miserable.
[1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/
====== Technical details
Software tag-based KASAN mode is implemented in a very similar way to the
generic one. This patchset essentially does the following:
1. TCR_TBI1 is set to enable Top Byte Ignore.
2. Shadow memory is used (with a different scale, 1:16, so each shadow
byte corresponds to 16 bytes of kernel memory) to store memory tags.
3. All slab objects are aligned to shadow scale, which is 16 bytes.
4. All pointers returned from the slab allocator are tagged with a random
tag and the corresponding shadow memory is poisoned with the same value.
5. Compiler instrumentation is used to insert tag checks. Either by
calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and
CONFIG_KASAN_INLINE flags are reused).
6. When a tag mismatch is detected in callback instrumentation mode
KASAN simply prints a bug report. In case of inline instrumentation,
clang inserts a brk instruction, and KASAN has it's own brk handler,
which reports the bug.
7. The memory in between slab objects is marked with a reserved tag, and
acts as a redzone.
8. When a slab object is freed it's marked with a reserved tag.
Bug detection is imprecise for two reasons:
1. We won't catch some small out-of-bounds accesses, that fall into the
same shadow cell, as the last byte of a slab object.
2. We only have 1 byte to store tags, which means we have a 1/256
probability of a tag match for an incorrect access (actually even
slightly less due to reserved tag values).
Despite that there's a particular type of bugs that tag-based KASAN can
detect compared to generic KASAN: use-after-free after the object has been
allocated by someone else.
====== Testing
Some kernel developers voiced a concern that changing the top byte of
kernel pointers may lead to subtle bugs that are difficult to discover.
To address this concern deliberate testing has been performed.
It doesn't seem feasible to do some kind of static checking to find
potential issues with pointer tagging, so a dynamic approach was taken.
All pointer comparisons/subtractions have been instrumented in an LLVM
compiler pass and a kernel module that would print a bug report whenever
two pointers with different tags are being compared/subtracted (ignoring
comparisons with NULL pointers and with pointers obtained by casting an
error code to a pointer type) has been used. Then the kernel has been
booted in QEMU and on an Odroid C2 board and syzkaller has been run.
This yielded the following results.
The two places that look interesting are:
is_vmalloc_addr in include/linux/mm.h
is_kernel_rodata in mm/util.c
Here we compare a pointer with some fixed untagged values to make sure
that the pointer lies in a particular part of the kernel address space.
Since tag-based KASAN doesn't add tags to pointers that belong to rodata
or vmalloc regions, this should work as is. To make sure debug checks to
those two functions that check that the result doesn't change whether we
operate on pointers with or without untagging has been added.
A few other cases that don't look that interesting:
Comparing pointers to achieve unique sorting order of pointee objects
(e.g. sorting locks addresses before performing a double lock):
tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c
pipe_double_lock in fs/pipe.c
unix_state_double_lock in net/unix/af_unix.c
lock_two_nondirectories in fs/inode.c
mutex_lock_double in kernel/events/core.c
ep_cmp_ffd in fs/eventpoll.c
fsnotify_compare_groups fs/notify/mark.c
Nothing needs to be done here, since the tags embedded into pointers
don't change, so the sorting order would still be unique.
Checks that a pointer belongs to some particular allocation:
is_sibling_entry in lib/radix-tree.c
object_is_on_stack in include/linux/sched/task_stack.h
Nothing needs to be done here either, since two pointers can only belong
to the same allocation if they have the same tag.
Overall, since the kernel boots and works, there are no critical bugs.
As for the rest, the traditional kernel testing way (use until fails) is
the only one that looks feasible.
Another point here is that tag-based KASAN is available under a separate
config option that needs to be deliberately enabled. Even though it might
be used in a "near-production" environment to find bugs that are not found
during fuzzing or running tests, it is still a debug tool.
====== Benchmarks
The following numbers were collected on Odroid C2 board. Both generic and
tag-based KASAN were used in inline instrumentation mode.
Boot time [1]:
* ~1.7 sec for clean kernel
* ~5.0 sec for generic KASAN
* ~5.0 sec for tag-based KASAN
Network performance [2]:
* 8.33 Gbits/sec for clean kernel
* 3.17 Gbits/sec for generic KASAN
* 2.85 Gbits/sec for tag-based KASAN
Slab memory usage after boot [3]:
* ~40 kb for clean kernel
* ~105 kb (~260% overhead) for generic KASAN
* ~47 kb (~20% overhead) for tag-based KASAN
KASAN memory overhead consists of three main parts:
1. Increased slab memory usage due to redzones.
2. Shadow memory (the whole reserved once during boot).
3. Quaratine (grows gradually until some preset limit; the more the limit,
the more the chance to detect a use-after-free).
Comparing tag-based vs generic KASAN for each of these points:
1. 20% vs 260% overhead.
2. 1/16th vs 1/8th of physical memory.
3. Tag-based KASAN doesn't require quarantine.
[1] Time before the ext4 driver is initialized.
[2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
[3] Measured as `cat /proc/meminfo | grep Slab`.
====== Some notes
A few notes:
1. The patchset can be found here:
https://github.com/xairy/kasan-prototype/tree/khwasan
2. Building requires a recent Clang version (7.0.0 or later).
3. Stack instrumentation is not supported yet and will be added later.
This patch (of 25):
Tag-based KASAN changes the value of the top byte of pointers returned
from the kernel allocation functions (such as kmalloc). This patch
updates KASAN hooks signatures and their usage in SLAB and SLUB code to
reflect that.
Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 00:29:37 -08:00
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2013-10-08 15:58:57 -07:00
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2019-02-20 22:19:11 -08:00
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2019-02-20 22:19:16 -08:00
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2013-10-08 15:58:57 -07:00
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2019-02-20 22:19:11 -08:00
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2013-10-08 15:58:57 -07:00
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2018-02-06 15:36:27 -08:00
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2013-10-08 15:58:57 -07:00
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2018-02-06 15:36:27 -08:00
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2013-10-08 15:58:57 -07:00
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2018-04-10 16:30:31 -07:00
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2013-10-08 15:58:57 -07:00
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2010-08-25 14:07:16 -05:00
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2014-08-06 16:04:18 -07:00
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2017-11-15 17:36:02 -08:00
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2014-08-06 16:04:18 -07:00
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2015-02-13 14:39:42 -08:00
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2018-04-10 16:30:31 -07:00
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2014-08-06 16:04:18 -07:00
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2008-04-14 19:11:40 +03:00
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2018-04-10 16:30:31 -07:00
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2015-11-20 15:57:46 -08:00
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mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
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2019-07-31 15:32:40 -04:00
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mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
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2019-07-31 15:32:40 -04:00
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mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
|
|
|
|
2019-07-31 15:32:40 -04:00
|
|
|
|
mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
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2015-11-20 15:57:46 -08:00
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2017-11-15 17:36:02 -08:00
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2015-11-20 15:57:46 -08:00
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mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
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2018-04-10 16:30:31 -07:00
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2015-11-20 15:57:46 -08:00
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2018-04-10 16:30:31 -07:00
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2015-11-20 15:57:46 -08:00
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2018-12-28 00:30:23 -08:00
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2015-09-04 15:45:48 -07:00
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2018-12-28 00:30:23 -08:00
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2015-09-04 15:45:48 -07:00
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2018-12-28 00:30:23 -08:00
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2015-09-04 15:45:48 -07:00
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2007-05-06 14:49:36 -07:00
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2014-06-04 16:06:38 -07:00
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2008-04-14 19:11:40 +03:00
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2014-06-04 16:06:38 -07:00
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2018-04-05 16:21:39 -07:00
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2008-04-14 19:11:40 +03:00
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2010-07-09 14:07:10 -05:00
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2014-06-04 16:06:38 -07:00
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2008-04-14 19:11:40 +03:00
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mm: rename alloc_pages_exact_node() to __alloc_pages_node()
alloc_pages_exact_node() was introduced in commit 6484eb3e2a81 ("page
allocator: do not check NUMA node ID when the caller knows the node is
valid") as an optimized variant of alloc_pages_node(), that doesn't
fallback to current node for nid == NUMA_NO_NODE. Unfortunately the
name of the function can easily suggest that the allocation is
restricted to the given node and fails otherwise. In truth, the node is
only preferred, unless __GFP_THISNODE is passed among the gfp flags.
The misleading name has lead to mistakes in the past, see for example
commits 5265047ac301 ("mm, thp: really limit transparent hugepage
allocation to local node") and b360edb43f8e ("mm, mempolicy:
migrate_to_node should only migrate to node").
Another issue with the name is that there's a family of
alloc_pages_exact*() functions where 'exact' means exact size (instead
of page order), which leads to more confusion.
To prevent further mistakes, this patch effectively renames
alloc_pages_exact_node() to __alloc_pages_node() to better convey that
it's an optimized variant of alloc_pages_node() not intended for general
usage. Both functions get described in comments.
It has been also considered to really provide a convenience function for
allocations restricted to a node, but the major opinion seems to be that
__GFP_THISNODE already provides that functionality and we shouldn't
duplicate the API needlessly. The number of users would be small
anyway.
Existing callers of alloc_pages_exact_node() are simply converted to
call __alloc_pages_node(), with the exception of sba_alloc_coherent()
which open-codes the check for NUMA_NO_NODE, so it is converted to use
alloc_pages_node() instead. This means it no longer performs some
VM_BUG_ON checks, and since the current check for nid in
alloc_pages_node() uses a 'nid < 0' comparison (which includes
NUMA_NO_NODE), it may hide wrong values which would be previously
exposed.
Both differences will be rectified by the next patch.
To sum up, this patch makes no functional changes, except temporarily
hiding potentially buggy callers. Restricting the checks in
alloc_pages_node() is left for the next patch which can in turn expose
more existing buggy callers.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Robin Holt <robinmholt@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Cliff Whickman <cpw@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:03:50 -07:00
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2014-06-04 16:06:38 -07:00
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2019-07-11 20:56:16 -07:00
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memcg: unify slab and other kmem pages charging
We have memcg_kmem_charge and memcg_kmem_uncharge methods for charging and
uncharging kmem pages to memcg, but currently they are not used for
charging slab pages (i.e. they are only used for charging pages allocated
with alloc_kmem_pages). The only reason why the slab subsystem uses
special helpers, memcg_charge_slab and memcg_uncharge_slab, is that it
needs to charge to the memcg of kmem cache while memcg_charge_kmem charges
to the memcg that the current task belongs to.
To remove this diversity, this patch adds an extra argument to
__memcg_kmem_charge that can be a pointer to a memcg or NULL. If it is
not NULL, the function tries to charge to the memcg it points to,
otherwise it charge to the current context. Next, it makes the slab
subsystem use this function to charge slab pages.
Since memcg_charge_kmem and memcg_uncharge_kmem helpers are now used only
in __memcg_kmem_charge and __memcg_kmem_uncharge, they are inlined. Since
__memcg_kmem_charge stores a pointer to the memcg in the page struct, we
don't need memcg_uncharge_slab anymore and can use free_kmem_pages.
Besides, one can now detect which memcg a slab page belongs to by reading
/proc/kpagecgroup.
Note, this patch switches slab to charge-after-alloc design. Since this
design is already used for all other memcg charges, it should not make any
difference.
[hannes@cmpxchg.org: better to have an outer function than a magic parameter for the memcg lookup]
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05 18:49:01 -08:00
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2014-06-04 16:06:38 -07:00
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2008-04-14 19:11:40 +03:00
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2016-07-26 15:21:59 -07:00
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2018-04-05 16:21:39 -07:00
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2016-07-26 15:21:59 -07:00
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2017-02-08 14:30:59 -08:00
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2016-07-26 15:21:59 -07:00
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2018-04-05 16:21:39 -07:00
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2016-07-26 15:21:59 -07:00
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2018-12-28 00:30:23 -08:00
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2016-07-26 15:21:59 -07:00
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2018-12-28 00:30:23 -08:00
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2016-07-26 15:21:59 -07:00
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2007-05-06 14:49:36 -07:00
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2008-01-07 23:20:27 -08:00
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2008-04-14 19:11:31 +03:00
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2009-06-24 21:59:51 +03:00
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2018-12-28 00:30:23 -08:00
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2015-09-04 15:45:48 -07:00
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2016-07-26 15:21:59 -07:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:44 -05:00
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2015-11-06 16:28:21 -08:00
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2011-06-01 12:25:44 -05:00
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2008-02-14 14:21:32 -08:00
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2007-10-16 01:25:52 -07:00
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2009-06-24 21:59:51 +03:00
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2015-11-06 16:28:21 -08:00
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mm: thp: set THP defrag by default to madvise and add a stall-free defrag option
THP defrag is enabled by default to direct reclaim/compact but not wake
kswapd in the event of a THP allocation failure. The problem is that
THP allocation requests potentially enter reclaim/compaction. This
potentially incurs a severe stall that is not guaranteed to be offset by
reduced TLB misses. While there has been considerable effort to reduce
the impact of reclaim/compaction, it is still a high cost and workloads
that should fit in memory fail to do so. Specifically, a simple
anon/file streaming workload will enter direct reclaim on NUMA at least
even though the working set size is 80% of RAM. It's been years and
it's time to throw in the towel.
First, this patch defines THP defrag as follows;
madvise: A failed allocation will direct reclaim/compact if the application requests it
never: Neither reclaim/compact nor wake kswapd
defer: A failed allocation will wake kswapd/kcompactd
always: A failed allocation will direct reclaim/compact (historical behaviour)
khugepaged defrag will enter direct/reclaim but not wake kswapd.
Next it sets the default defrag option to be "madvise" to only enter
direct reclaim/compaction for applications that specifically requested
it.
Lastly, it removes a check from the page allocator slowpath that is
related to __GFP_THISNODE to allow "defer" to work. The callers that
really cares are slub/slab and they are updated accordingly. The slab
one may be surprising because it also corrects a comment as kswapd was
never woken up by that path.
This means that a THP fault will no longer stall for most applications
by default and the ideal for most users that get THP if they are
immediately available. There are still options for users that prefer a
stall at startup of a new application by either restoring historical
behaviour with "always" or pick a half-way point with "defer" where
kswapd does some of the work in the background and wakes kcompactd if
necessary. THP defrag for khugepaged remains enabled and will enter
direct/reclaim but no wakeup kswapd or kcompactd.
After this patch a THP allocation failure will quickly fallback and rely
on khugepaged to recover the situation at some time in the future. In
some cases, this will reduce THP usage but the benefit of THP is hard to
measure and not a universal win where as a stall to reclaim/compaction
is definitely measurable and can be painful.
The first test for this is using "usemem" to read a large file and write
a large anonymous mapping (to avoid the zero page) multiple times. The
total size of the mappings is 80% of RAM and the benchmark simply
measures how long it takes to complete. It uses multiple threads to see
if that is a factor. On UMA, the performance is almost identical so is
not reported but on NUMA, we see this
usemem
4.4.0 4.4.0
kcompactd-v1r1 nodefrag-v1r3
Amean System-1 102.86 ( 0.00%) 46.81 ( 54.50%)
Amean System-4 37.85 ( 0.00%) 34.02 ( 10.12%)
Amean System-7 48.12 ( 0.00%) 46.89 ( 2.56%)
Amean System-12 51.98 ( 0.00%) 56.96 ( -9.57%)
Amean System-21 80.16 ( 0.00%) 79.05 ( 1.39%)
Amean System-30 110.71 ( 0.00%) 107.17 ( 3.20%)
Amean System-48 127.98 ( 0.00%) 124.83 ( 2.46%)
Amean Elapsd-1 185.84 ( 0.00%) 105.51 ( 43.23%)
Amean Elapsd-4 26.19 ( 0.00%) 25.58 ( 2.33%)
Amean Elapsd-7 21.65 ( 0.00%) 21.62 ( 0.16%)
Amean Elapsd-12 18.58 ( 0.00%) 17.94 ( 3.43%)
Amean Elapsd-21 17.53 ( 0.00%) 16.60 ( 5.33%)
Amean Elapsd-30 17.45 ( 0.00%) 17.13 ( 1.84%)
Amean Elapsd-48 15.40 ( 0.00%) 15.27 ( 0.82%)
For a single thread, the benchmark completes 43.23% faster with this
patch applied with smaller benefits as the thread increases. Similar,
notice the large reduction in most cases in system CPU usage. The
overall CPU time is
4.4.0 4.4.0
kcompactd-v1r1 nodefrag-v1r3
User 10357.65 10438.33
System 3988.88 3543.94
Elapsed 2203.01 1634.41
Which is substantial. Now, the reclaim figures
4.4.0 4.4.0
kcompactd-v1r1nodefrag-v1r3
Minor Faults 128458477 278352931
Major Faults 2174976 225
Swap Ins 16904701 0
Swap Outs 17359627 0
Allocation stalls 43611 0
DMA allocs 0 0
DMA32 allocs 19832646 19448017
Normal allocs 614488453 580941839
Movable allocs 0 0
Direct pages scanned 24163800 0
Kswapd pages scanned 0 0
Kswapd pages reclaimed 0 0
Direct pages reclaimed 20691346 0
Compaction stalls 42263 0
Compaction success 938 0
Compaction failures 41325 0
This patch eliminates almost all swapping and direct reclaim activity.
There is still overhead but it's from NUMA balancing which does not
identify that it's pointless trying to do anything with this workload.
I also tried the thpscale benchmark which forces a corner case where
compaction can be used heavily and measures the latency of whether base
or huge pages were used
thpscale Fault Latencies
4.4.0 4.4.0
kcompactd-v1r1 nodefrag-v1r3
Amean fault-base-1 5288.84 ( 0.00%) 2817.12 ( 46.73%)
Amean fault-base-3 6365.53 ( 0.00%) 3499.11 ( 45.03%)
Amean fault-base-5 6526.19 ( 0.00%) 4363.06 ( 33.15%)
Amean fault-base-7 7142.25 ( 0.00%) 4858.08 ( 31.98%)
Amean fault-base-12 13827.64 ( 0.00%) 10292.11 ( 25.57%)
Amean fault-base-18 18235.07 ( 0.00%) 13788.84 ( 24.38%)
Amean fault-base-24 21597.80 ( 0.00%) 24388.03 (-12.92%)
Amean fault-base-30 26754.15 ( 0.00%) 19700.55 ( 26.36%)
Amean fault-base-32 26784.94 ( 0.00%) 19513.57 ( 27.15%)
Amean fault-huge-1 4223.96 ( 0.00%) 2178.57 ( 48.42%)
Amean fault-huge-3 2194.77 ( 0.00%) 2149.74 ( 2.05%)
Amean fault-huge-5 2569.60 ( 0.00%) 2346.95 ( 8.66%)
Amean fault-huge-7 3612.69 ( 0.00%) 2997.70 ( 17.02%)
Amean fault-huge-12 3301.75 ( 0.00%) 6727.02 (-103.74%)
Amean fault-huge-18 6696.47 ( 0.00%) 6685.72 ( 0.16%)
Amean fault-huge-24 8000.72 ( 0.00%) 9311.43 (-16.38%)
Amean fault-huge-30 13305.55 ( 0.00%) 9750.45 ( 26.72%)
Amean fault-huge-32 9981.71 ( 0.00%) 10316.06 ( -3.35%)
The average time to fault pages is substantially reduced in the majority
of caseds but with the obvious caveat that fewer THPs are actually used
in this adverse workload
4.4.0 4.4.0
kcompactd-v1r1 nodefrag-v1r3
Percentage huge-1 0.71 ( 0.00%) 14.04 (1865.22%)
Percentage huge-3 10.77 ( 0.00%) 33.05 (206.85%)
Percentage huge-5 60.39 ( 0.00%) 38.51 (-36.23%)
Percentage huge-7 45.97 ( 0.00%) 34.57 (-24.79%)
Percentage huge-12 68.12 ( 0.00%) 40.07 (-41.17%)
Percentage huge-18 64.93 ( 0.00%) 47.82 (-26.35%)
Percentage huge-24 62.69 ( 0.00%) 44.23 (-29.44%)
Percentage huge-30 43.49 ( 0.00%) 55.38 ( 27.34%)
Percentage huge-32 50.72 ( 0.00%) 51.90 ( 2.35%)
4.4.0 4.4.0
kcompactd-v1r1nodefrag-v1r3
Minor Faults 37429143 47564000
Major Faults 1916 1558
Swap Ins 1466 1079
Swap Outs 2936863 149626
Allocation stalls 62510 3
DMA allocs 0 0
DMA32 allocs 6566458 6401314
Normal allocs 216361697 216538171
Movable allocs 0 0
Direct pages scanned 25977580 17998
Kswapd pages scanned 0 3638931
Kswapd pages reclaimed 0 207236
Direct pages reclaimed 8833714 88
Compaction stalls 103349 5
Compaction success 270 4
Compaction failures 103079 1
Note again that while this does swap as it's an aggressive workload, the
direct relcim activity and allocation stalls is substantially reduced.
There is some kswapd activity but ftrace showed that the kswapd activity
was due to normal wakeups from 4K pages being allocated.
Compaction-related stalls and activity are almost eliminated.
I also tried the stutter benchmark. For this, I do not have figures for
NUMA but it's something that does impact UMA so I'll report what is
available
stutter
4.4.0 4.4.0
kcompactd-v1r1 nodefrag-v1r3
Min mmap 7.3571 ( 0.00%) 7.3438 ( 0.18%)
1st-qrtle mmap 7.5278 ( 0.00%) 17.9200 (-138.05%)
2nd-qrtle mmap 7.6818 ( 0.00%) 21.6055 (-181.25%)
3rd-qrtle mmap 11.0889 ( 0.00%) 21.8881 (-97.39%)
Max-90% mmap 27.8978 ( 0.00%) 22.1632 ( 20.56%)
Max-93% mmap 28.3202 ( 0.00%) 22.3044 ( 21.24%)
Max-95% mmap 28.5600 ( 0.00%) 22.4580 ( 21.37%)
Max-99% mmap 29.6032 ( 0.00%) 25.5216 ( 13.79%)
Max mmap 4109.7289 ( 0.00%) 4813.9832 (-17.14%)
Mean mmap 12.4474 ( 0.00%) 19.3027 (-55.07%)
This benchmark is trying to fault an anonymous mapping while there is a
heavy IO load -- a scenario that desktop users used to complain about
frequently. This shows a mix because the ideal case of mapping with THP
is not hit as often. However, note that 99% of the mappings complete
13.79% faster. The CPU usage here is particularly interesting
4.4.0 4.4.0
kcompactd-v1r1nodefrag-v1r3
User 67.50 0.99
System 1327.88 91.30
Elapsed 2079.00 2128.98
And once again we look at the reclaim figures
4.4.0 4.4.0
kcompactd-v1r1nodefrag-v1r3
Minor Faults 335241922 1314582827
Major Faults 715 819
Swap Ins 0 0
Swap Outs 0 0
Allocation stalls 532723 0
DMA allocs 0 0
DMA32 allocs 1822364341 1177950222
Normal allocs 1815640808 1517844854
Movable allocs 0 0
Direct pages scanned 21892772 0
Kswapd pages scanned 20015890 41879484
Kswapd pages reclaimed 19961986 41822072
Direct pages reclaimed 21892741 0
Compaction stalls 1065755 0
Compaction success 514 0
Compaction failures 1065241 0
Allocation stalls and all direct reclaim activity is eliminated as well
as compaction-related stalls.
THP gives impressive gains in some cases but only if they are quickly
available. We're not going to reach the point where they are completely
free so lets take the costs out of the fast paths finally and defer the
cost to kswapd, kcompactd and khugepaged where it belongs.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-17 14:19:23 -07:00
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2009-06-24 21:59:51 +03:00
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2014-06-04 16:06:38 -07:00
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2008-04-14 19:11:40 +03:00
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2014-03-12 17:26:20 +09:00
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2008-04-14 19:11:40 +03:00
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2014-06-04 16:06:38 -07:00
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2015-09-04 15:45:48 -07:00
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2008-04-14 19:11:40 +03:00
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2008-04-04 00:54:48 +02:00
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2008-04-14 19:11:31 +03:00
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2007-05-06 14:49:36 -07:00
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2012-12-18 14:22:50 -08:00
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slub: Commonize slab_cache field in struct page
Right now, slab and slub have fields in struct page to derive which
cache a page belongs to, but they do it slightly differently.
slab uses a field called slab_cache, that lives in the third double
word. slub, uses a field called "slab", living outside of the
doublewords area.
Ideally, we could use the same field for this. Since slub heavily makes
use of the doubleword region, there isn't really much room to move
slub's slab_cache field around. Since slab does not have such strict
placement restrictions, we can move it outside the doubleword area.
The naming used by slab, "slab_cache", is less confusing, and it is
preferred over slub's generic "slab".
Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-10-22 18:05:36 +04:00
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2012-05-18 00:47:47 +09:00
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2015-08-21 14:11:51 -07:00
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mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon. Swap over the network is considered as an option in diskless
systems. The two likely scenarios are when blade servers are used as part
of a cluster where the form factor or maintenance costs do not allow the
use of disks and thin clients.
The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap according to the manual at
https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download
There is also documentation and tutorials on how to setup swap over NBD at
places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The
nbd-client also documents the use of NBD as swap. Despite this, the fact
is that a machine using NBD for swap can deadlock within minutes if swap
is used intensively. This patch series addresses the problem.
The core issue is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need. Some years ago, Peter Zijlstra developed a series of
patches that supported swap over an NFS that at least one distribution is
carrying within their kernels. This patch series borrows very heavily
from Peter's work to support swapping over NBD as a pre-requisite to
supporting swap-over-NFS. The bulk of the complexity is concerned with
preserving memory that is allocated from the PFMEMALLOC reserves for use
by the network layer which is needed for both NBD and NFS.
Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeing memory.
Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required
Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 7-12 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean pages. If
packets are received and stored in pages that were allocated under
low-memory situations and are unrelated to the VM, the packets
are dropped.
Patch 11 reintroduces __skb_alloc_page which the networking
folk may object to but is needed in some cases to propogate
pfmemalloc from a newly allocated page to an skb. If there is a
strong objection, this patch can be dropped with the impact being
that swap-over-network will be slower in some cases but it should
not fail.
Patch 13 is a micro-optimisation to avoid a function call in the
common case.
Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 15 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get throttled on
a waitqueue if 50% of the PFMEMALLOC reserves are depleted. It is
expected that kswapd and the direct reclaimers already running
will clean enough pages for the low watermark to be reached and
the throttled processes are woken up.
Patch 16 adds a statistic to track how often processes get throttled
Some basic performance testing was run using kernel builds, netperf on
loopback for UDP and TCP, hackbench (pipes and sockets), iozone and
sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant performance
variances.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 8*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure.
Without the patches and using SLUB, the machine locks up within minutes
and runs to completion with them applied. With SLAB, the story is
different as an unpatched kernel run to completion. However, the patched
kernel completed the test 45% faster.
MICRO
3.5.0-rc2 3.5.0-rc2
vanilla swapnbd
Unrecognised test vmscan-anon-mmap-write
MMTests Statistics: duration
Sys Time Running Test (seconds) 197.80 173.07
User+Sys Time Running Test (seconds) 206.96 182.03
Total Elapsed Time (seconds) 3240.70 1762.09
This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
Allocations of pages below the min watermark run a risk of the machine
hanging due to a lack of memory. To prevent this, only callers who have
PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated to
a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
When this patch is applied, pages allocated from below the low watermark
are returned with page->pfmemalloc set and it is up to the caller to
determine how the page should be protected. SLAB restricts access to any
page with page->pfmemalloc set to callers which are known to able to
access the PFMEMALLOC reserve. If one is not available, an attempt is
made to allocate a new page rather than use a reserve. SLUB is a bit more
relaxed in that it only records if the current per-CPU page was allocated
from PFMEMALLOC reserve and uses another partial slab if the caller does
not have the necessary GFP or process flags. This was found to be
sufficient in tests to avoid hangs due to SLUB generally maintaining
smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators can fail
a slab allocation even though free objects are available because they are
being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
[sebastian@breakpoint.cc: Correct order of page flag clearing]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 16:43:58 -07:00
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2007-05-06 14:49:36 -07:00
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2019-02-20 22:19:23 -08:00
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2007-05-06 14:49:36 -07:00
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2019-02-20 22:19:23 -08:00
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2015-02-13 14:39:42 -08:00
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2016-07-26 15:21:59 -07:00
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2018-12-28 00:30:23 -08:00
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2019-02-20 22:19:28 -08:00
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:24 -05:00
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2011-06-01 12:25:46 -05:00
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2015-09-04 15:45:48 -07:00
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2007-05-06 14:49:36 -07:00
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2015-11-06 16:28:21 -08:00
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2015-09-04 15:45:48 -07:00
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2007-05-06 14:49:36 -07:00
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2015-09-04 15:45:48 -07:00
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2016-07-26 15:22:02 -07:00
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2016-07-26 15:22:05 -07:00
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2017-02-22 15:41:02 -08:00
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2015-09-04 15:45:48 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:31 +03:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:06 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:31 +03:00
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2010-09-29 07:15:01 -05:00
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2007-05-06 14:49:36 -07:00
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mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon. Swap over the network is considered as an option in diskless
systems. The two likely scenarios are when blade servers are used as part
of a cluster where the form factor or maintenance costs do not allow the
use of disks and thin clients.
The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap according to the manual at
https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download
There is also documentation and tutorials on how to setup swap over NBD at
places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The
nbd-client also documents the use of NBD as swap. Despite this, the fact
is that a machine using NBD for swap can deadlock within minutes if swap
is used intensively. This patch series addresses the problem.
The core issue is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need. Some years ago, Peter Zijlstra developed a series of
patches that supported swap over an NFS that at least one distribution is
carrying within their kernels. This patch series borrows very heavily
from Peter's work to support swapping over NBD as a pre-requisite to
supporting swap-over-NFS. The bulk of the complexity is concerned with
preserving memory that is allocated from the PFMEMALLOC reserves for use
by the network layer which is needed for both NBD and NFS.
Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeing memory.
Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required
Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 7-12 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean pages. If
packets are received and stored in pages that were allocated under
low-memory situations and are unrelated to the VM, the packets
are dropped.
Patch 11 reintroduces __skb_alloc_page which the networking
folk may object to but is needed in some cases to propogate
pfmemalloc from a newly allocated page to an skb. If there is a
strong objection, this patch can be dropped with the impact being
that swap-over-network will be slower in some cases but it should
not fail.
Patch 13 is a micro-optimisation to avoid a function call in the
common case.
Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 15 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get throttled on
a waitqueue if 50% of the PFMEMALLOC reserves are depleted. It is
expected that kswapd and the direct reclaimers already running
will clean enough pages for the low watermark to be reached and
the throttled processes are woken up.
Patch 16 adds a statistic to track how often processes get throttled
Some basic performance testing was run using kernel builds, netperf on
loopback for UDP and TCP, hackbench (pipes and sockets), iozone and
sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant performance
variances.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 8*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure.
Without the patches and using SLUB, the machine locks up within minutes
and runs to completion with them applied. With SLAB, the story is
different as an unpatched kernel run to completion. However, the patched
kernel completed the test 45% faster.
MICRO
3.5.0-rc2 3.5.0-rc2
vanilla swapnbd
Unrecognised test vmscan-anon-mmap-write
MMTests Statistics: duration
Sys Time Running Test (seconds) 197.80 173.07
User+Sys Time Running Test (seconds) 206.96 182.03
Total Elapsed Time (seconds) 3240.70 1762.09
This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
Allocations of pages below the min watermark run a risk of the machine
hanging due to a lack of memory. To prevent this, only callers who have
PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated to
a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
When this patch is applied, pages allocated from below the low watermark
are returned with page->pfmemalloc set and it is up to the caller to
determine how the page should be protected. SLAB restricts access to any
page with page->pfmemalloc set to callers which are known to able to
access the PFMEMALLOC reserve. If one is not available, an attempt is
made to allocate a new page rather than use a reserve. SLUB is a bit more
relaxed in that it only records if the current per-CPU page was allocated
from PFMEMALLOC reserve and uses another partial slab if the caller does
not have the necessary GFP or process flags. This was found to be
sufficient in tests to avoid hangs due to SLUB generally maintaining
smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators can fail
a slab allocation even though free objects are available because they are
being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
[sebastian@breakpoint.cc: Correct order of page flag clearing]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 16:43:58 -07:00
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2008-04-14 18:52:18 +03:00
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2012-12-18 14:22:50 -08:00
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2018-06-07 17:08:26 -07:00
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2009-05-05 19:13:44 +10:00
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2019-07-11 20:56:16 -07:00
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2016-03-17 14:17:35 -07:00
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2007-05-06 14:49:36 -07:00
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2018-06-07 17:09:05 -07:00
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2011-03-10 15:22:00 +08:00
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slub: Commonize slab_cache field in struct page
Right now, slab and slub have fields in struct page to derive which
cache a page belongs to, but they do it slightly differently.
slab uses a field called slab_cache, that lives in the third double
word. slub, uses a field called "slab", living outside of the
doublewords area.
Ideally, we could use the same field for this. Since slub heavily makes
use of the doubleword region, there isn't really much room to move
slub's slab_cache field around. Since slab does not have such strict
placement restrictions, we can move it outside the doubleword area.
The naming used by slab, "slab_cache", is less confusing, and it is
preferred over slub's generic "slab".
Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-10-22 18:05:36 +04:00
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2007-05-06 14:49:36 -07:00
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2017-01-18 02:53:44 -08:00
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2018-06-07 17:09:05 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:50 -05:00
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2007-05-06 14:49:36 -07:00
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2014-02-10 14:25:46 -08:00
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2007-05-06 14:49:36 -07:00
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2007-05-06 14:49:44 -07:00
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2011-08-24 08:57:52 +08:00
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2019-05-13 17:16:12 -07:00
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2008-01-07 23:20:27 -08:00
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2019-05-13 17:16:12 -07:00
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2007-05-06 14:49:36 -07:00
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2014-02-10 14:25:46 -08:00
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2011-06-01 12:25:50 -05:00
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2010-09-28 08:10:28 -05:00
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2014-01-10 13:23:49 +01:00
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2019-05-13 17:16:12 -07:00
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2016-02-17 13:11:37 -08:00
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2010-09-28 08:10:28 -05:00
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2007-05-06 14:49:36 -07:00
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2012-05-09 10:09:53 -05:00
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:26 -05:00
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:26 -05:00
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2011-08-09 16:12:25 -05:00
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slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-01-21 17:01:25 +09:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:52 -05:00
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2014-01-10 13:23:49 +01:00
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2011-06-01 12:25:52 -05:00
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2012-05-09 10:09:53 -05:00
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slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-01-21 17:01:25 +09:00
|
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|
2012-06-04 10:14:58 +03:00
|
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2012-05-09 10:09:53 -05:00
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2012-06-04 10:14:58 +03:00
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2011-06-01 12:25:52 -05:00
|
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2014-01-29 14:05:50 -08:00
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2012-05-09 10:09:53 -05:00
|
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2011-06-01 12:25:52 -05:00
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2012-05-09 10:09:53 -05:00
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2011-06-01 12:25:52 -05:00
|
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2012-05-17 00:13:02 +09:00
|
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2012-05-09 10:09:53 -05:00
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2011-06-01 12:25:52 -05:00
|
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2012-05-09 10:09:53 -05:00
|
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2011-08-09 16:12:27 -05:00
|
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2007-05-06 14:49:36 -07:00
|
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|
slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-01-21 17:01:25 +09:00
|
|
|
|
2012-09-17 14:09:09 -07:00
|
|
|
|
2011-08-09 16:12:27 -05:00
|
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|
|
2007-05-06 14:49:36 -07:00
|
|
|
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2007-05-09 02:32:39 -07:00
|
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2007-05-06 14:49:36 -07:00
|
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2012-09-17 14:09:09 -07:00
|
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:27 -05:00
|
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|
|
2018-04-05 16:21:10 -07:00
|
|
|
|
slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-01-21 17:01:25 +09:00
|
|
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|
2007-05-06 14:49:36 -07:00
|
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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|
|
2019-05-13 17:16:12 -07:00
|
|
|
|
2012-09-17 14:09:09 -07:00
|
|
|
|
2011-08-09 16:12:27 -05:00
|
|
|
|
2012-09-17 14:09:09 -07:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-01-21 17:01:25 +09:00
|
|
|
|
2011-08-09 16:12:27 -05:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-01-21 17:01:25 +09:00
|
|
|
|
2011-09-07 10:26:36 +08:00
|
|
|
|
2011-08-09 16:12:27 -05:00
|
|
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|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-01-21 17:01:25 +09:00
|
|
|
|
2012-02-03 23:34:56 +08:00
|
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|
|
2011-08-09 16:12:27 -05:00
|
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|
|
2013-06-19 14:05:52 +09:00
|
|
|
|
2017-07-06 15:36:34 -07:00
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2011-08-09 16:12:27 -05:00
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2011-08-09 16:12:26 -05:00
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:26 -05:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2012-01-27 00:12:23 -08:00
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2011-08-09 16:12:25 -05:00
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2007-05-06 14:49:36 -07:00
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2008-04-28 02:12:17 -07:00
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2008-04-28 02:12:16 -07:00
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2011-08-09 16:12:26 -05:00
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cpuset: mm: reduce large amounts of memory barrier related damage v3
Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.
[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths. This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32. The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.
For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.
This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side. This is much cheaper on some architectures, including x86. The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.
While updating the nodemask, a check is made to see if a false failure
is a risk. If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.
In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
actual results were
3.3.0-rc3 3.3.0-rc3
rc3-vanilla nobarrier-v2r1
Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 135.68 132.17
User+Sys Time Running Test (seconds) 164.2 160.13
Total Elapsed Time (seconds) 123.46 120.87
The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected). The
actual number of page faults is noticeably improved.
For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.
To test the actual bug the commit fixed I opened two terminals. The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data. In a second window, the nodemask of the
cpuset was continually randomised in a loop.
Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 16:34:11 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2016-05-19 17:10:43 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2008-01-07 23:20:26 -08:00
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2007-05-06 14:49:36 -07:00
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cpuset: mm: reduce large amounts of memory barrier related damage v3
Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.
[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths. This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32. The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.
For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.
This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side. This is much cheaper on some architectures, including x86. The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.
While updating the nodemask, a check is made to see if a false failure
is a risk. If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.
In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
actual results were
3.3.0-rc3 3.3.0-rc3
rc3-vanilla nobarrier-v2r1
Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 135.68 132.17
User+Sys Time Running Test (seconds) 164.2 160.13
Total Elapsed Time (seconds) 123.46 120.87
The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected). The
actual number of page faults is noticeably improved.
For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.
To test the actual bug the commit fixed I opened two terminals. The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data. In a second window, the nodemask of the
cpuset was continually randomised in a loop.
Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 16:34:11 -07:00
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2014-04-03 14:47:24 -07:00
|
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2014-04-07 15:37:29 -07:00
|
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|
cpuset: mm: reduce large amounts of memory barrier related damage v3
Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.
[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths. This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32. The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.
For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.
This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side. This is much cheaper on some architectures, including x86. The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.
While updating the nodemask, a check is made to see if a false failure
is a risk. If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.
In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
actual results were
3.3.0-rc3 3.3.0-rc3
rc3-vanilla nobarrier-v2r1
Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 135.68 132.17
User+Sys Time Running Test (seconds) 164.2 160.13
Total Elapsed Time (seconds) 123.46 120.87
The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected). The
actual number of page faults is noticeably improved.
For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.
To test the actual bug the commit fixed I opened two terminals. The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data. In a second window, the nodemask of the
cpuset was continually randomised in a loop.
Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 16:34:11 -07:00
|
|
|
|
|
|
|
|
|
2007-05-06 14:49:36 -07:00
|
|
|
|
cpuset: mm: reduce large amounts of memory barrier related damage v3
Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.
[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths. This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32. The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.
For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.
This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side. This is much cheaper on some architectures, including x86. The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.
While updating the nodemask, a check is made to see if a false failure
is a risk. If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.
In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
actual results were
3.3.0-rc3 3.3.0-rc3
rc3-vanilla nobarrier-v2r1
Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 135.68 132.17
User+Sys Time Running Test (seconds) 164.2 160.13
Total Elapsed Time (seconds) 123.46 120.87
The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected). The
actual number of page faults is noticeably improved.
For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.
To test the actual bug the commit fixed I opened two terminals. The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data. In a second window, the nodemask of the
cpuset was continually randomised in a loop.
Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 16:34:11 -07:00
|
|
|
|
2007-05-06 14:49:36 -07:00
|
|
|
|
2014-12-12 16:58:28 -08:00
|
|
|
|
cpuset: mm: reduce large amounts of memory barrier related damage v3
Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.
[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths. This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32. The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.
For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.
This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side. This is much cheaper on some architectures, including x86. The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.
While updating the nodemask, a check is made to see if a false failure
is a risk. If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.
In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
actual results were
3.3.0-rc3 3.3.0-rc3
rc3-vanilla nobarrier-v2r1
Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 135.68 132.17
User+Sys Time Running Test (seconds) 164.2 160.13
Total Elapsed Time (seconds) 123.46 120.87
The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected). The
actual number of page faults is noticeably improved.
For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.
To test the actual bug the commit fixed I opened two terminals. The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data. In a second window, the nodemask of the
cpuset was continually randomised in a loop.
Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 16:34:11 -07:00
|
|
|
|
2012-09-17 14:09:09 -07:00
|
|
|
|
cpuset: mm: reduce large amounts of memory barrier related damage v3
Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.
[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths. This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32. The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.
For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.
This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side. This is much cheaper on some architectures, including x86. The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.
While updating the nodemask, a check is made to see if a false failure
is a risk. If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.
In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
actual results were
3.3.0-rc3 3.3.0-rc3
rc3-vanilla nobarrier-v2r1
Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 135.68 132.17
User+Sys Time Running Test (seconds) 164.2 160.13
Total Elapsed Time (seconds) 123.46 120.87
The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected). The
actual number of page faults is noticeably improved.
For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.
To test the actual bug the commit fixed I opened two terminals. The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data. In a second window, the nodemask of the
cpuset was continually randomised in a loop.
Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 16:34:11 -07:00
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|
2014-04-03 14:47:24 -07:00
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cpuset: mm: reduce large amounts of memory barrier related damage v3
Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") wins a super prize for the largest number of
memory barriers entered into fast paths for one commit.
[get|put]_mems_allowed is incredibly heavy with pairs of full memory
barriers inserted into a number of hot paths. This was detected while
investigating at large page allocator slowdown introduced some time
after 2.6.32. The largest portion of this overhead was shown by
oprofile to be at an mfence introduced by this commit into the page
allocator hot path.
For extra style points, the commit introduced the use of yield() in an
implementation of what looks like a spinning mutex.
This patch replaces the full memory barriers on both read and write
sides with a sequence counter with just read barriers on the fast path
side. This is much cheaper on some architectures, including x86. The
main bulk of the patch is the retry logic if the nodemask changes in a
manner that can cause a false failure.
While updating the nodemask, a check is made to see if a false failure
is a risk. If it is, the sequence number gets bumped and parallel
allocators will briefly stall while the nodemask update takes place.
In a page fault test microbenchmark, oprofile samples from
__alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
actual results were
3.3.0-rc3 3.3.0-rc3
rc3-vanilla nobarrier-v2r1
Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
MMTests Statistics: duration
Sys Time Running Test (seconds) 135.68 132.17
User+Sys Time Running Test (seconds) 164.2 160.13
Total Elapsed Time (seconds) 123.46 120.87
The overall improvement is small but the System CPU time is much
improved and roughly in correlation to what oprofile reported (these
performance figures are without profiling so skew is expected). The
actual number of page faults is noticeably improved.
For benchmarks like kernel builds, the overall benefit is marginal but
the system CPU time is slightly reduced.
To test the actual bug the commit fixed I opened two terminals. The
first ran within a cpuset and continually ran a small program that
faulted 100M of anonymous data. In a second window, the nodemask of the
cpuset was continually randomised in a loop.
Without the commit, the program would fail every so often (usually
within 10 seconds) and obviously with the commit everything worked fine.
With this patch applied, it also worked fine so the fix should be
functionally equivalent.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 16:34:11 -07:00
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2010-05-24 14:32:08 -07:00
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2007-05-06 14:49:36 -07:00
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2014-04-03 14:47:24 -07:00
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2019-05-13 17:16:09 -07:00
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:26 -05:00
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2011-08-09 16:12:25 -05:00
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:26 -05:00
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2014-10-09 15:26:15 -07:00
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2007-05-06 14:49:36 -07:00
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2012-09-17 14:09:09 -07:00
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2011-08-09 16:12:26 -05:00
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:25 -05:00
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2007-05-06 14:49:36 -07:00
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2011-02-25 11:38:54 -06:00
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2014-06-04 16:06:34 -07:00
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2011-02-25 11:38:54 -06:00
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2014-06-04 16:06:34 -07:00
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2011-02-25 11:38:54 -06:00
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2014-06-04 16:06:34 -07:00
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2011-02-25 11:38:54 -06:00
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2014-06-04 16:06:34 -07:00
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2011-02-25 11:38:54 -06:00
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2011-03-22 13:35:00 -05:00
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2011-02-25 11:38:54 -06:00
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2012-09-28 16:34:05 +08:00
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2011-02-25 11:38:54 -06:00
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2011-06-01 12:25:52 -05:00
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2007-05-06 14:49:36 -07:00
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2013-07-15 09:05:29 +08:00
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2017-07-06 15:36:25 -07:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:52 -05:00
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2011-08-24 08:57:52 +08:00
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2011-06-01 12:25:52 -05:00
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2008-02-07 17:47:41 -08:00
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2011-06-01 12:25:52 -05:00
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2009-12-18 16:26:23 -06:00
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2011-08-24 08:57:52 +08:00
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2007-05-10 03:15:16 -07:00
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2011-06-01 12:25:52 -05:00
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2014-01-29 14:05:50 -08:00
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2011-06-01 12:25:52 -05:00
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2011-07-14 12:49:12 -05:00
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2011-06-01 12:25:52 -05:00
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2014-01-29 14:05:50 -08:00
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2011-06-01 12:25:52 -05:00
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2014-07-02 15:22:35 -07:00
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2011-06-01 12:25:52 -05:00
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2019-03-05 15:46:22 -08:00
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2011-06-01 12:25:52 -05:00
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2014-01-10 13:23:49 +01:00
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2011-06-01 12:25:52 -05:00
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2018-12-28 00:33:13 -08:00
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2011-06-01 12:25:52 -05:00
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2018-12-28 00:33:13 -08:00
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2011-06-01 12:25:52 -05:00
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2011-07-14 12:49:12 -05:00
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2011-06-01 12:25:52 -05:00
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2018-12-28 00:33:13 -08:00
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2011-06-01 12:25:52 -05:00
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2017-07-06 15:36:25 -07:00
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2007-05-06 14:49:36 -07:00
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2012-05-18 22:01:17 +09:00
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2012-11-28 16:23:00 +00:00
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2012-05-18 22:01:17 +09:00
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2012-11-28 16:23:00 +00:00
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2011-08-09 16:12:27 -05:00
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2013-06-19 14:05:52 +09:00
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slub: refactoring unfreeze_partials()
Current implementation of unfreeze_partials() is so complicated,
but benefit from it is insignificant. In addition many code in
do {} while loop have a bad influence to a fail rate of cmpxchg_double_slab.
Under current implementation which test status of cpu partial slab
and acquire list_lock in do {} while loop,
we don't need to acquire a list_lock and gain a little benefit
when front of the cpu partial slab is to be discarded, but this is a rare case.
In case that add_partial is performed and cmpxchg_double_slab is failed,
remove_partial should be called case by case.
I think that these are disadvantages of current implementation,
so I do refactoring unfreeze_partials().
Minimizing code in do {} while loop introduce a reduced fail rate
of cmpxchg_double_slab. Below is output of 'slabinfo -r kmalloc-256'
when './perf stat -r 33 hackbench 50 process 4000 > /dev/null' is done.
** before **
Cmpxchg_double Looping
------------------------
Locked Cmpxchg Double redos 182685
Unlocked Cmpxchg Double redos 0
** after **
Cmpxchg_double Looping
------------------------
Locked Cmpxchg Double redos 177995
Unlocked Cmpxchg Double redos 1
We can see cmpxchg_double_slab fail rate is improved slightly.
Bolow is output of './perf stat -r 30 hackbench 50 process 4000 > /dev/null'.
** before **
Performance counter stats for './hackbench 50 process 4000' (30 runs):
108517.190463 task-clock # 7.926 CPUs utilized ( +- 0.24% )
2,919,550 context-switches # 0.027 M/sec ( +- 3.07% )
100,774 CPU-migrations # 0.929 K/sec ( +- 4.72% )
124,201 page-faults # 0.001 M/sec ( +- 0.15% )
401,500,234,387 cycles # 3.700 GHz ( +- 0.24% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
250,576,913,354 instructions # 0.62 insns per cycle ( +- 0.13% )
45,934,956,860 branches # 423.297 M/sec ( +- 0.14% )
188,219,787 branch-misses # 0.41% of all branches ( +- 0.56% )
13.691837307 seconds time elapsed ( +- 0.24% )
** after **
Performance counter stats for './hackbench 50 process 4000' (30 runs):
107784.479767 task-clock # 7.928 CPUs utilized ( +- 0.22% )
2,834,781 context-switches # 0.026 M/sec ( +- 2.33% )
93,083 CPU-migrations # 0.864 K/sec ( +- 3.45% )
123,967 page-faults # 0.001 M/sec ( +- 0.15% )
398,781,421,836 cycles # 3.700 GHz ( +- 0.22% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
250,189,160,419 instructions # 0.63 insns per cycle ( +- 0.09% )
45,855,370,128 branches # 425.436 M/sec ( +- 0.10% )
169,881,248 branch-misses # 0.37% of all branches ( +- 0.43% )
13.596272341 seconds time elapsed ( +- 0.22% )
No regression is found, but rather we can see slightly better result.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-06-09 02:23:16 +09:00
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2011-11-14 13:34:13 +08:00
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2011-08-09 16:12:27 -05:00
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slub: refactoring unfreeze_partials()
Current implementation of unfreeze_partials() is so complicated,
but benefit from it is insignificant. In addition many code in
do {} while loop have a bad influence to a fail rate of cmpxchg_double_slab.
Under current implementation which test status of cpu partial slab
and acquire list_lock in do {} while loop,
we don't need to acquire a list_lock and gain a little benefit
when front of the cpu partial slab is to be discarded, but this is a rare case.
In case that add_partial is performed and cmpxchg_double_slab is failed,
remove_partial should be called case by case.
I think that these are disadvantages of current implementation,
so I do refactoring unfreeze_partials().
Minimizing code in do {} while loop introduce a reduced fail rate
of cmpxchg_double_slab. Below is output of 'slabinfo -r kmalloc-256'
when './perf stat -r 33 hackbench 50 process 4000 > /dev/null' is done.
** before **
Cmpxchg_double Looping
------------------------
Locked Cmpxchg Double redos 182685
Unlocked Cmpxchg Double redos 0
** after **
Cmpxchg_double Looping
------------------------
Locked Cmpxchg Double redos 177995
Unlocked Cmpxchg Double redos 1
We can see cmpxchg_double_slab fail rate is improved slightly.
Bolow is output of './perf stat -r 30 hackbench 50 process 4000 > /dev/null'.
** before **
Performance counter stats for './hackbench 50 process 4000' (30 runs):
108517.190463 task-clock # 7.926 CPUs utilized ( +- 0.24% )
2,919,550 context-switches # 0.027 M/sec ( +- 3.07% )
100,774 CPU-migrations # 0.929 K/sec ( +- 4.72% )
124,201 page-faults # 0.001 M/sec ( +- 0.15% )
401,500,234,387 cycles # 3.700 GHz ( +- 0.24% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
250,576,913,354 instructions # 0.62 insns per cycle ( +- 0.13% )
45,934,956,860 branches # 423.297 M/sec ( +- 0.14% )
188,219,787 branch-misses # 0.41% of all branches ( +- 0.56% )
13.691837307 seconds time elapsed ( +- 0.24% )
** after **
Performance counter stats for './hackbench 50 process 4000' (30 runs):
107784.479767 task-clock # 7.928 CPUs utilized ( +- 0.22% )
2,834,781 context-switches # 0.026 M/sec ( +- 2.33% )
93,083 CPU-migrations # 0.864 K/sec ( +- 3.45% )
123,967 page-faults # 0.001 M/sec ( +- 0.15% )
398,781,421,836 cycles # 3.700 GHz ( +- 0.22% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
250,189,160,419 instructions # 0.63 insns per cycle ( +- 0.09% )
45,855,370,128 branches # 425.436 M/sec ( +- 0.10% )
169,881,248 branch-misses # 0.37% of all branches ( +- 0.43% )
13.596272341 seconds time elapsed ( +- 0.22% )
No regression is found, but rather we can see slightly better result.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-06-09 02:23:16 +09:00
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2011-08-09 16:12:27 -05:00
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2014-01-29 14:05:50 -08:00
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2011-08-09 16:12:27 -05:00
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2012-05-18 22:01:17 +09:00
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2011-08-09 16:12:27 -05:00
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2014-07-02 15:22:35 -07:00
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2011-11-14 13:34:13 +08:00
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slub: refactoring unfreeze_partials()
Current implementation of unfreeze_partials() is so complicated,
but benefit from it is insignificant. In addition many code in
do {} while loop have a bad influence to a fail rate of cmpxchg_double_slab.
Under current implementation which test status of cpu partial slab
and acquire list_lock in do {} while loop,
we don't need to acquire a list_lock and gain a little benefit
when front of the cpu partial slab is to be discarded, but this is a rare case.
In case that add_partial is performed and cmpxchg_double_slab is failed,
remove_partial should be called case by case.
I think that these are disadvantages of current implementation,
so I do refactoring unfreeze_partials().
Minimizing code in do {} while loop introduce a reduced fail rate
of cmpxchg_double_slab. Below is output of 'slabinfo -r kmalloc-256'
when './perf stat -r 33 hackbench 50 process 4000 > /dev/null' is done.
** before **
Cmpxchg_double Looping
------------------------
Locked Cmpxchg Double redos 182685
Unlocked Cmpxchg Double redos 0
** after **
Cmpxchg_double Looping
------------------------
Locked Cmpxchg Double redos 177995
Unlocked Cmpxchg Double redos 1
We can see cmpxchg_double_slab fail rate is improved slightly.
Bolow is output of './perf stat -r 30 hackbench 50 process 4000 > /dev/null'.
** before **
Performance counter stats for './hackbench 50 process 4000' (30 runs):
108517.190463 task-clock # 7.926 CPUs utilized ( +- 0.24% )
2,919,550 context-switches # 0.027 M/sec ( +- 3.07% )
100,774 CPU-migrations # 0.929 K/sec ( +- 4.72% )
124,201 page-faults # 0.001 M/sec ( +- 0.15% )
401,500,234,387 cycles # 3.700 GHz ( +- 0.24% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
250,576,913,354 instructions # 0.62 insns per cycle ( +- 0.13% )
45,934,956,860 branches # 423.297 M/sec ( +- 0.14% )
188,219,787 branch-misses # 0.41% of all branches ( +- 0.56% )
13.691837307 seconds time elapsed ( +- 0.24% )
** after **
Performance counter stats for './hackbench 50 process 4000' (30 runs):
107784.479767 task-clock # 7.928 CPUs utilized ( +- 0.22% )
2,834,781 context-switches # 0.026 M/sec ( +- 2.33% )
93,083 CPU-migrations # 0.864 K/sec ( +- 3.45% )
123,967 page-faults # 0.001 M/sec ( +- 0.15% )
398,781,421,836 cycles # 3.700 GHz ( +- 0.22% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
250,189,160,419 instructions # 0.63 insns per cycle ( +- 0.09% )
45,855,370,128 branches # 425.436 M/sec ( +- 0.10% )
169,881,248 branch-misses # 0.37% of all branches ( +- 0.43% )
13.596272341 seconds time elapsed ( +- 0.22% )
No regression is found, but rather we can see slightly better result.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-06-09 02:23:16 +09:00
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2011-08-09 16:12:27 -05:00
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2011-11-14 13:34:13 +08:00
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2019-05-13 17:16:09 -07:00
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2011-08-09 16:12:27 -05:00
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2019-03-05 15:43:10 -08:00
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2011-08-09 16:12:27 -05:00
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slub: correct to calculate num of acquired objects in get_partial_node()
There is a subtle bug when calculating a number of acquired objects.
Currently, we calculate "available = page->objects - page->inuse",
after acquire_slab() is called in get_partial_node().
In acquire_slab() with mode = 1, we always set new.inuse = page->objects.
So,
acquire_slab(s, n, page, object == NULL);
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
available = page->objects - page->inuse;
!!! availabe is always 0 !!!
...
Therfore, "available > s->cpu_partial / 2" is always false and
we always go to second iteration.
This patch correct this problem.
After that, we don't need return value of put_cpu_partial().
So remove it.
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2013-01-21 17:01:25 +09:00
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2011-08-09 16:12:27 -05:00
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2013-06-19 14:05:52 +09:00
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2011-08-09 16:12:27 -05:00
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slub: make dead caches discard free slabs immediately
To speed up further allocations SLUB may store empty slabs in per cpu/node
partial lists instead of freeing them immediately. This prevents per
memcg caches destruction, because kmem caches created for a memory cgroup
are only destroyed after the last page charged to the cgroup is freed.
To fix this issue, this patch resurrects approach first proposed in [1].
It forbids SLUB to cache empty slabs after the memory cgroup that the
cache belongs to was destroyed. It is achieved by setting kmem_cache's
cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so
that it would drop frozen empty slabs immediately if cpu_partial = 0.
The runtime overhead is minimal. From all the hot functions, we only
touch relatively cold put_cpu_partial(): we make it call
unfreeze_partials() after freezing a slab that belongs to an offline
memory cgroup. Since slab freezing exists to avoid moving slabs from/to a
partial list on free/alloc, and there can't be allocations from dead
caches, it shouldn't cause any overhead. We do have to disable preemption
for put_cpu_partial() to achieve that though.
The original patch was accepted well and even merged to the mm tree.
However, I decided to withdraw it due to changes happening to the memcg
core at that time. I had an idea of introducing per-memcg shrinkers for
kmem caches, but now, as memcg has finally settled down, I do not see it
as an option, because SLUB shrinker would be too costly to call since SLUB
does not keep free slabs on a separate list. Besides, we currently do not
even call per-memcg shrinkers for offline memcgs. Overall, it would
introduce much more complexity to both SLUB and memcg than this small
patch.
Regarding to SLAB, there's no problem with it, because it shrinks
per-cpu/node caches periodically. Thanks to list_lru reparenting, we no
longer keep entries for offline cgroups in per-memcg arrays (such as
memcg_cache_params->memcg_caches), so we do not have to bother if a
per-memcg cache will be shrunk a bit later than it could be.
[1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 14:59:47 -08:00
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2011-08-09 16:12:27 -05:00
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2012-11-28 16:23:00 +00:00
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2011-08-09 16:12:27 -05:00
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2012-06-23 03:22:38 +09:00
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2011-08-09 16:12:27 -05:00
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2012-02-03 23:34:56 +08:00
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2011-08-09 16:12:27 -05:00
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2013-07-15 09:05:29 +08:00
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slub: make dead caches discard free slabs immediately
To speed up further allocations SLUB may store empty slabs in per cpu/node
partial lists instead of freeing them immediately. This prevents per
memcg caches destruction, because kmem caches created for a memory cgroup
are only destroyed after the last page charged to the cgroup is freed.
To fix this issue, this patch resurrects approach first proposed in [1].
It forbids SLUB to cache empty slabs after the memory cgroup that the
cache belongs to was destroyed. It is achieved by setting kmem_cache's
cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so
that it would drop frozen empty slabs immediately if cpu_partial = 0.
The runtime overhead is minimal. From all the hot functions, we only
touch relatively cold put_cpu_partial(): we make it call
unfreeze_partials() after freezing a slab that belongs to an offline
memory cgroup. Since slab freezing exists to avoid moving slabs from/to a
partial list on free/alloc, and there can't be allocations from dead
caches, it shouldn't cause any overhead. We do have to disable preemption
for put_cpu_partial() to achieve that though.
The original patch was accepted well and even merged to the mm tree.
However, I decided to withdraw it due to changes happening to the memcg
core at that time. I had an idea of introducing per-memcg shrinkers for
kmem caches, but now, as memcg has finally settled down, I do not see it
as an option, because SLUB shrinker would be too costly to call since SLUB
does not keep free slabs on a separate list. Besides, we currently do not
even call per-memcg shrinkers for offline memcgs. Overall, it would
introduce much more complexity to both SLUB and memcg than this small
patch.
Regarding to SLAB, there's no problem with it, because it shrinks
per-cpu/node caches periodically. Thanks to list_lru reparenting, we no
longer keep entries for offline cgroups in per-memcg arrays (such as
memcg_cache_params->memcg_caches), so we do not have to bother if a
per-memcg cache will be shrunk a bit later than it could be.
[1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 14:59:47 -08:00
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2019-05-13 17:16:09 -07:00
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2011-08-09 16:12:27 -05:00
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2007-10-16 01:26:05 -07:00
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2007-05-06 14:49:36 -07:00
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2009-12-18 16:26:23 -06:00
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2017-07-06 15:36:25 -07:00
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2012-05-09 10:09:57 -05:00
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2007-05-06 14:49:36 -07:00
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2008-02-15 23:45:26 -08:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:24 -07:00
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2007-05-06 14:49:36 -07:00
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2009-12-18 16:26:20 -06:00
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2007-05-06 14:49:36 -07:00
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2018-12-28 00:33:06 -08:00
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2011-08-09 16:12:27 -05:00
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2018-12-28 00:33:06 -08:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:26:05 -07:00
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2007-05-06 14:49:36 -07:00
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2012-03-28 14:42:44 -07:00
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2017-07-06 15:36:31 -07:00
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2012-03-28 14:42:44 -07:00
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2007-05-06 14:49:36 -07:00
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2012-03-28 14:42:44 -07:00
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2007-05-06 14:49:36 -07:00
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2016-08-18 14:57:19 +02:00
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2007-10-16 01:26:05 -07:00
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2012-05-09 10:09:59 -05:00
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2007-10-16 01:26:05 -07:00
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2018-12-28 00:33:09 -08:00
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2007-10-16 01:26:05 -07:00
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mm, slab: suppress out of memory warning unless debug is enabled
When the slab or slub allocators cannot allocate additional slab pages,
they emit diagnostic information to the kernel log such as current
number of slabs, number of objects, active objects, etc. This is always
coupled with a page allocation failure warning since it is controlled by
!__GFP_NOWARN.
Suppress this out of memory warning if the allocator is configured
without debug supported. The page allocation failure warning will
indicate it is a failed slab allocation, the order, and the gfp mask, so
this is only useful to diagnose allocator issues.
Since CONFIG_SLUB_DEBUG is already enabled by default for the slub
allocator, there is no functional change with this patch. If debug is
disabled, however, the warnings are now suppressed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:36 -07:00
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2009-06-10 18:50:32 +03:00
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mm, slab: suppress out of memory warning unless debug is enabled
When the slab or slub allocators cannot allocate additional slab pages,
they emit diagnostic information to the kernel log such as current
number of slabs, number of objects, active objects, etc. This is always
coupled with a page allocation failure warning since it is controlled by
!__GFP_NOWARN.
Suppress this out of memory warning if the allocator is configured
without debug supported. The page allocation failure warning will
indicate it is a failed slab allocation, the order, and the gfp mask, so
this is only useful to diagnose allocator issues.
Since CONFIG_SLUB_DEBUG is already enabled by default for the slub
allocator, there is no functional change with this patch. If debug is
disabled, however, the warnings are now suppressed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:36 -07:00
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2009-06-10 18:50:32 +03:00
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2019-05-13 17:16:12 -07:00
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2009-06-10 18:50:32 +03:00
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mm, slab: suppress out of memory warning unless debug is enabled
When the slab or slub allocators cannot allocate additional slab pages,
they emit diagnostic information to the kernel log such as current
number of slabs, number of objects, active objects, etc. This is always
coupled with a page allocation failure warning since it is controlled by
!__GFP_NOWARN.
Suppress this out of memory warning if the allocator is configured
without debug supported. The page allocation failure warning will
indicate it is a failed slab allocation, the order, and the gfp mask, so
this is only useful to diagnose allocator issues.
Since CONFIG_SLUB_DEBUG is already enabled by default for the slub
allocator, there is no functional change with this patch. If debug is
disabled, however, the warnings are now suppressed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:36 -07:00
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2009-06-11 14:08:48 +04:00
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2009-06-10 18:50:32 +03:00
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mm, slab: suppress out of memory warning unless debug is enabled
When the slab or slub allocators cannot allocate additional slab pages,
they emit diagnostic information to the kernel log such as current
number of slabs, number of objects, active objects, etc. This is always
coupled with a page allocation failure warning since it is controlled by
!__GFP_NOWARN.
Suppress this out of memory warning if the allocator is configured
without debug supported. The page allocation failure warning will
indicate it is a failed slab allocation, the order, and the gfp mask, so
this is only useful to diagnose allocator issues.
Since CONFIG_SLUB_DEBUG is already enabled by default for the slub
allocator, there is no functional change with this patch. If debug is
disabled, however, the warnings are now suppressed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:36 -07:00
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2009-06-10 18:50:32 +03:00
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2014-08-06 16:04:09 -07:00
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2009-06-10 18:50:32 +03:00
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|
mm, slab: suppress out of memory warning unless debug is enabled
When the slab or slub allocators cannot allocate additional slab pages,
they emit diagnostic information to the kernel log such as current
number of slabs, number of objects, active objects, etc. This is always
coupled with a page allocation failure warning since it is controlled by
!__GFP_NOWARN.
Suppress this out of memory warning if the allocator is configured
without debug supported. The page allocation failure warning will
indicate it is a failed slab allocation, the order, and the gfp mask, so
this is only useful to diagnose allocator issues.
Since CONFIG_SLUB_DEBUG is already enabled by default for the slub
allocator, there is no functional change with this patch. If debug is
disabled, however, the warnings are now suppressed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:36 -07:00
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2016-03-15 14:56:33 -07:00
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2018-04-05 16:21:39 -07:00
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2014-06-04 16:06:34 -07:00
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2009-06-10 18:50:32 +03:00
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2012-06-13 10:24:57 -05:00
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2014-06-04 16:06:34 -07:00
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2009-07-07 00:14:14 -07:00
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2014-08-06 16:04:09 -07:00
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2009-06-10 18:50:32 +03:00
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2009-06-11 14:08:48 +04:00
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2009-06-10 18:50:32 +03:00
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2014-06-04 16:06:34 -07:00
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2009-06-10 18:50:32 +03:00
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mm, slab: suppress out of memory warning unless debug is enabled
When the slab or slub allocators cannot allocate additional slab pages,
they emit diagnostic information to the kernel log such as current
number of slabs, number of objects, active objects, etc. This is always
coupled with a page allocation failure warning since it is controlled by
!__GFP_NOWARN.
Suppress this out of memory warning if the allocator is configured
without debug supported. The page allocation failure warning will
indicate it is a failed slab allocation, the order, and the gfp mask, so
this is only useful to diagnose allocator issues.
Since CONFIG_SLUB_DEBUG is already enabled by default for the slub
allocator, there is no functional change with this patch. If debug is
disabled, however, the warnings are now suppressed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:36 -07:00
|
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2009-06-10 18:50:32 +03:00
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2011-08-09 16:12:26 -05:00
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2012-05-09 10:09:51 -05:00
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2012-05-09 10:09:55 -05:00
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2011-08-09 16:12:26 -05:00
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2018-06-07 17:05:13 -07:00
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2012-05-09 10:09:55 -05:00
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2011-08-09 16:12:26 -05:00
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2014-06-04 16:07:56 -07:00
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2011-08-09 16:12:26 -05:00
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2012-05-09 10:09:51 -05:00
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2011-08-09 16:12:26 -05:00
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2019-03-05 15:42:00 -08:00
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2011-08-09 16:12:26 -05:00
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2012-05-09 10:09:51 -05:00
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2011-08-09 16:12:26 -05:00
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mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon. Swap over the network is considered as an option in diskless
systems. The two likely scenarios are when blade servers are used as part
of a cluster where the form factor or maintenance costs do not allow the
use of disks and thin clients.
The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap according to the manual at
https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download
There is also documentation and tutorials on how to setup swap over NBD at
places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The
nbd-client also documents the use of NBD as swap. Despite this, the fact
is that a machine using NBD for swap can deadlock within minutes if swap
is used intensively. This patch series addresses the problem.
The core issue is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need. Some years ago, Peter Zijlstra developed a series of
patches that supported swap over an NFS that at least one distribution is
carrying within their kernels. This patch series borrows very heavily
from Peter's work to support swapping over NBD as a pre-requisite to
supporting swap-over-NFS. The bulk of the complexity is concerned with
preserving memory that is allocated from the PFMEMALLOC reserves for use
by the network layer which is needed for both NBD and NFS.
Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeing memory.
Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required
Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 7-12 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean pages. If
packets are received and stored in pages that were allocated under
low-memory situations and are unrelated to the VM, the packets
are dropped.
Patch 11 reintroduces __skb_alloc_page which the networking
folk may object to but is needed in some cases to propogate
pfmemalloc from a newly allocated page to an skb. If there is a
strong objection, this patch can be dropped with the impact being
that swap-over-network will be slower in some cases but it should
not fail.
Patch 13 is a micro-optimisation to avoid a function call in the
common case.
Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 15 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get throttled on
a waitqueue if 50% of the PFMEMALLOC reserves are depleted. It is
expected that kswapd and the direct reclaimers already running
will clean enough pages for the low watermark to be reached and
the throttled processes are woken up.
Patch 16 adds a statistic to track how often processes get throttled
Some basic performance testing was run using kernel builds, netperf on
loopback for UDP and TCP, hackbench (pipes and sockets), iozone and
sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant performance
variances.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 8*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure.
Without the patches and using SLUB, the machine locks up within minutes
and runs to completion with them applied. With SLAB, the story is
different as an unpatched kernel run to completion. However, the patched
kernel completed the test 45% faster.
MICRO
3.5.0-rc2 3.5.0-rc2
vanilla swapnbd
Unrecognised test vmscan-anon-mmap-write
MMTests Statistics: duration
Sys Time Running Test (seconds) 197.80 173.07
User+Sys Time Running Test (seconds) 206.96 182.03
Total Elapsed Time (seconds) 3240.70 1762.09
This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
Allocations of pages below the min watermark run a risk of the machine
hanging due to a lack of memory. To prevent this, only callers who have
PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated to
a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
When this patch is applied, pages allocated from below the low watermark
are returned with page->pfmemalloc set and it is up to the caller to
determine how the page should be protected. SLAB restricts access to any
page with page->pfmemalloc set to callers which are known to able to
access the PFMEMALLOC reserve. If one is not available, an attempt is
made to allocate a new page rather than use a reserve. SLUB is a bit more
relaxed in that it only records if the current per-CPU page was allocated
from PFMEMALLOC reserve and uses another partial slab if the caller does
not have the necessary GFP or process flags. This was found to be
sufficient in tests to avoid hangs due to SLUB generally maintaining
smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators can fail
a slab allocation even though free objects are available because they are
being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
[sebastian@breakpoint.cc: Correct order of page flag clearing]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 16:43:58 -07:00
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2011-11-11 14:07:14 -06:00
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2013-07-15 09:05:29 +08:00
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2011-11-11 14:07:14 -06:00
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2012-05-18 22:01:17 +09:00
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2011-11-11 14:07:14 -06:00
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2012-05-09 10:09:51 -05:00
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2011-11-11 14:07:14 -06:00
|
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2014-01-29 14:05:50 -08:00
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2011-11-11 14:07:14 -06:00
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2012-05-18 22:01:17 +09:00
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2011-11-11 14:07:14 -06:00
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2007-05-06 14:49:36 -07:00
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2007-05-10 03:15:16 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-10 03:15:16 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-10 03:15:16 -07:00
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2008-02-15 23:45:26 -08:00
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2015-11-20 15:57:35 -08:00
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2007-05-06 14:49:36 -07:00
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2015-11-20 15:57:35 -08:00
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2008-08-19 20:43:25 +03:00
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2007-05-06 14:49:36 -07:00
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2012-05-09 10:09:51 -05:00
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2012-05-09 10:09:58 -05:00
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2007-05-06 14:49:36 -07:00
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2012-05-09 10:09:58 -05:00
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2007-05-06 14:49:36 -07:00
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2011-08-09 16:12:27 -05:00
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2012-05-09 10:09:51 -05:00
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2012-05-09 10:09:59 -05:00
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2014-10-09 15:26:15 -07:00
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2017-07-06 15:36:25 -07:00
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2014-10-09 15:26:15 -07:00
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2011-06-01 12:25:56 -05:00
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2008-02-15 23:45:26 -08:00
|
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|
mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon. Swap over the network is considered as an option in diskless
systems. The two likely scenarios are when blade servers are used as part
of a cluster where the form factor or maintenance costs do not allow the
use of disks and thin clients.
The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap according to the manual at
https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download
There is also documentation and tutorials on how to setup swap over NBD at
places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The
nbd-client also documents the use of NBD as swap. Despite this, the fact
is that a machine using NBD for swap can deadlock within minutes if swap
is used intensively. This patch series addresses the problem.
The core issue is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need. Some years ago, Peter Zijlstra developed a series of
patches that supported swap over an NFS that at least one distribution is
carrying within their kernels. This patch series borrows very heavily
from Peter's work to support swapping over NBD as a pre-requisite to
supporting swap-over-NFS. The bulk of the complexity is concerned with
preserving memory that is allocated from the PFMEMALLOC reserves for use
by the network layer which is needed for both NBD and NFS.
Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeing memory.
Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required
Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 7-12 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean pages. If
packets are received and stored in pages that were allocated under
low-memory situations and are unrelated to the VM, the packets
are dropped.
Patch 11 reintroduces __skb_alloc_page which the networking
folk may object to but is needed in some cases to propogate
pfmemalloc from a newly allocated page to an skb. If there is a
strong objection, this patch can be dropped with the impact being
that swap-over-network will be slower in some cases but it should
not fail.
Patch 13 is a micro-optimisation to avoid a function call in the
common case.
Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 15 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get throttled on
a waitqueue if 50% of the PFMEMALLOC reserves are depleted. It is
expected that kswapd and the direct reclaimers already running
will clean enough pages for the low watermark to be reached and
the throttled processes are woken up.
Patch 16 adds a statistic to track how often processes get throttled
Some basic performance testing was run using kernel builds, netperf on
loopback for UDP and TCP, hackbench (pipes and sockets), iozone and
sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant performance
variances.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 8*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure.
Without the patches and using SLUB, the machine locks up within minutes
and runs to completion with them applied. With SLAB, the story is
different as an unpatched kernel run to completion. However, the patched
kernel completed the test 45% faster.
MICRO
3.5.0-rc2 3.5.0-rc2
vanilla swapnbd
Unrecognised test vmscan-anon-mmap-write
MMTests Statistics: duration
Sys Time Running Test (seconds) 197.80 173.07
User+Sys Time Running Test (seconds) 206.96 182.03
Total Elapsed Time (seconds) 3240.70 1762.09
This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
Allocations of pages below the min watermark run a risk of the machine
hanging due to a lack of memory. To prevent this, only callers who have
PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated to
a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
When this patch is applied, pages allocated from below the low watermark
are returned with page->pfmemalloc set and it is up to the caller to
determine how the page should be protected. SLAB restricts access to any
page with page->pfmemalloc set to callers which are known to able to
access the PFMEMALLOC reserve. If one is not available, an attempt is
made to allocate a new page rather than use a reserve. SLUB is a bit more
relaxed in that it only records if the current per-CPU page was allocated
from PFMEMALLOC reserve and uses another partial slab if the caller does
not have the necessary GFP or process flags. This was found to be
sufficient in tests to avoid hangs due to SLUB generally maintaining
smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators can fail
a slab allocation even though free objects are available because they are
being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
[sebastian@breakpoint.cc: Correct order of page flag clearing]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 16:43:58 -07:00
|
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|
2017-07-06 15:36:25 -07:00
|
|
|
|
mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon. Swap over the network is considered as an option in diskless
systems. The two likely scenarios are when blade servers are used as part
of a cluster where the form factor or maintenance costs do not allow the
use of disks and thin clients.
The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap according to the manual at
https://sourceforge.net/projects/ltsp/files/Docs-Admin-Guide/LTSPManual.pdf/download
There is also documentation and tutorials on how to setup swap over NBD at
places like https://help.ubuntu.com/community/UbuntuLTSP/EnableNBDSWAP The
nbd-client also documents the use of NBD as swap. Despite this, the fact
is that a machine using NBD for swap can deadlock within minutes if swap
is used intensively. This patch series addresses the problem.
The core issue is that network block devices do not use mempools like
normal block devices do. As the host cannot control where they receive
packets from, they cannot reliably work out in advance how much memory
they might need. Some years ago, Peter Zijlstra developed a series of
patches that supported swap over an NFS that at least one distribution is
carrying within their kernels. This patch series borrows very heavily
from Peter's work to support swapping over NBD as a pre-requisite to
supporting swap-over-NFS. The bulk of the complexity is concerned with
preserving memory that is allocated from the PFMEMALLOC reserves for use
by the network layer which is needed for both NBD and NFS.
Patch 1 adds knowledge of the PFMEMALLOC reserves to SLAB and SLUB to
preserve access to pages allocated under low memory situations
to callers that are freeing memory.
Patch 2 optimises the SLUB fast path to avoid pfmemalloc checks
Patch 3 introduces __GFP_MEMALLOC to allow access to the PFMEMALLOC
reserves without setting PFMEMALLOC.
Patch 4 opens the possibility for softirqs to use PFMEMALLOC reserves
for later use by network packet processing.
Patch 5 only sets page->pfmemalloc when ALLOC_NO_WATERMARKS was required
Patch 6 ignores memory policies when ALLOC_NO_WATERMARKS is set.
Patches 7-12 allows network processing to use PFMEMALLOC reserves when
the socket has been marked as being used by the VM to clean pages. If
packets are received and stored in pages that were allocated under
low-memory situations and are unrelated to the VM, the packets
are dropped.
Patch 11 reintroduces __skb_alloc_page which the networking
folk may object to but is needed in some cases to propogate
pfmemalloc from a newly allocated page to an skb. If there is a
strong objection, this patch can be dropped with the impact being
that swap-over-network will be slower in some cases but it should
not fail.
Patch 13 is a micro-optimisation to avoid a function call in the
common case.
Patch 14 tags NBD sockets as being SOCK_MEMALLOC so they can use
PFMEMALLOC if necessary.
Patch 15 notes that it is still possible for the PFMEMALLOC reserve
to be depleted. To prevent this, direct reclaimers get throttled on
a waitqueue if 50% of the PFMEMALLOC reserves are depleted. It is
expected that kswapd and the direct reclaimers already running
will clean enough pages for the low watermark to be reached and
the throttled processes are woken up.
Patch 16 adds a statistic to track how often processes get throttled
Some basic performance testing was run using kernel builds, netperf on
loopback for UDP and TCP, hackbench (pipes and sockets), iozone and
sysbench. Each of them were expected to use the sl*b allocators
reasonably heavily but there did not appear to be significant performance
variances.
For testing swap-over-NBD, a machine was booted with 2G of RAM with a
swapfile backed by NBD. 8*NUM_CPU processes were started that create
anonymous memory mappings and read them linearly in a loop. The total
size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
memory pressure.
Without the patches and using SLUB, the machine locks up within minutes
and runs to completion with them applied. With SLAB, the story is
different as an unpatched kernel run to completion. However, the patched
kernel completed the test 45% faster.
MICRO
3.5.0-rc2 3.5.0-rc2
vanilla swapnbd
Unrecognised test vmscan-anon-mmap-write
MMTests Statistics: duration
Sys Time Running Test (seconds) 197.80 173.07
User+Sys Time Running Test (seconds) 206.96 182.03
Total Elapsed Time (seconds) 3240.70 1762.09
This patch: mm: sl[au]b: add knowledge of PFMEMALLOC reserve pages
Allocations of pages below the min watermark run a risk of the machine
hanging due to a lack of memory. To prevent this, only callers who have
PF_MEMALLOC or TIF_MEMDIE set and are not processing an interrupt are
allowed to allocate with ALLOC_NO_WATERMARKS. Once they are allocated to
a slab though, nothing prevents other callers consuming free objects
within those slabs. This patch limits access to slab pages that were
alloced from the PFMEMALLOC reserves.
When this patch is applied, pages allocated from below the low watermark
are returned with page->pfmemalloc set and it is up to the caller to
determine how the page should be protected. SLAB restricts access to any
page with page->pfmemalloc set to callers which are known to able to
access the PFMEMALLOC reserve. If one is not available, an attempt is
made to allocate a new page rather than use a reserve. SLUB is a bit more
relaxed in that it only records if the current per-CPU page was allocated
from PFMEMALLOC reserve and uses another partial slab if the caller does
not have the necessary GFP or process flags. This was found to be
sufficient in tests to avoid hangs due to SLUB generally maintaining
smaller lists than SLAB.
In low-memory conditions it does mean that !PFMEMALLOC allocators can fail
a slab allocation even though free objects are available because they are
being preserved for callers that are freeing pages.
[a.p.zijlstra@chello.nl: Original implementation]
[sebastian@breakpoint.cc: Correct order of page flag clearing]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 16:43:58 -07:00
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2011-12-13 04:57:06 +01:00
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2012-05-09 10:09:51 -05:00
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2011-12-13 04:57:06 +01:00
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2012-05-09 10:09:58 -05:00
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2008-02-15 23:45:26 -08:00
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2012-05-09 10:09:51 -05:00
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2011-06-01 12:25:58 -05:00
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2011-06-01 12:25:56 -05:00
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2011-06-01 12:25:58 -05:00
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2008-02-15 23:45:26 -08:00
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2009-12-18 16:26:23 -06:00
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2008-02-15 23:45:26 -08:00
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2007-05-10 03:15:16 -07:00
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2012-05-09 10:09:52 -05:00
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2014-01-29 14:05:50 -08:00
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2012-05-09 10:09:51 -05:00
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2011-02-25 11:38:54 -06:00
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2012-05-09 10:09:51 -05:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:52 -05:00
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2017-07-06 15:36:31 -07:00
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2011-08-09 16:12:27 -05:00
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2007-05-06 14:49:36 -07:00
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2012-05-09 10:09:55 -05:00
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2007-10-16 23:25:51 -07:00
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2012-05-09 10:09:54 -05:00
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mm, slab: suppress out of memory warning unless debug is enabled
When the slab or slub allocators cannot allocate additional slab pages,
they emit diagnostic information to the kernel log such as current
number of slabs, number of objects, active objects, etc. This is always
coupled with a page allocation failure warning since it is controlled by
!__GFP_NOWARN.
Suppress this out of memory warning if the allocator is configured
without debug supported. The page allocation failure warning will
indicate it is a failed slab allocation, the order, and the gfp mask, so
this is only useful to diagnose allocator issues.
Since CONFIG_SLUB_DEBUG is already enabled by default for the slub
allocator, there is no functional change with this patch. If debug is
disabled, however, the warnings are now suppressed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:36 -07:00
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2012-05-09 10:09:54 -05:00
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2007-05-06 14:49:36 -07:00
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2007-05-10 03:15:16 -07:00
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2012-05-09 10:09:58 -05:00
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2012-07-31 16:44:00 -07:00
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2007-05-16 22:10:53 -07:00
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2007-05-10 03:15:16 -07:00
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2011-08-09 16:12:26 -05:00
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2013-07-15 09:05:29 +08:00
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2011-08-09 16:12:26 -05:00
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2011-06-01 12:25:52 -05:00
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2017-07-06 15:36:25 -07:00
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2012-05-09 10:09:51 -05:00
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2007-05-10 03:15:16 -07:00
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2015-11-20 15:57:35 -08:00
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2007-05-10 03:15:16 -07:00
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2012-09-08 17:47:58 -03:00
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2008-08-19 20:43:25 +03:00
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2007-05-10 03:15:16 -07:00
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2015-11-20 15:57:52 -08:00
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2007-10-16 01:26:05 -07:00
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2012-05-09 10:09:59 -05:00
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2011-02-25 11:38:54 -06:00
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2008-01-07 23:20:30 -08:00
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memcg: fix possible use-after-free in memcg_kmem_get_cache()
Suppose task @t that belongs to a memory cgroup @memcg is going to
allocate an object from a kmem cache @c. The copy of @c corresponding to
@memcg, @mc, is empty. Then if kmem_cache_alloc races with the memory
cgroup destruction we can access the memory cgroup's copy of the cache
after it was destroyed:
CPU0 CPU1
---- ----
[ current=@t
@mc->memcg_params->nr_pages=0 ]
kmem_cache_alloc(@c):
call memcg_kmem_get_cache(@c);
proceed to allocation from @mc:
alloc a page for @mc:
...
move @t from @memcg
destroy @memcg:
mem_cgroup_css_offline(@memcg):
memcg_unregister_all_caches(@memcg):
kmem_cache_destroy(@mc)
add page to @mc
We could fix this issue by taking a reference to a per-memcg cache, but
that would require adding a per-cpu reference counter to per-memcg caches,
which would look cumbersome.
Instead, let's take a reference to a memory cgroup, which already has a
per-cpu reference counter, in the beginning of kmem_cache_alloc to be
dropped in the end, and move per memcg caches destruction from css offline
to css free. As a side effect, per-memcg caches will be destroyed not one
by one, but all at once when the last page accounted to the memory cgroup
is freed. This doesn't sound as a high price for code readability though.
Note, this patch does add some overhead to the kmem_cache_alloc hot path,
but it is pretty negligible - it's just a function call plus a per cpu
counter decrement, which is comparable to what we already have in
memcg_kmem_get_cache. Besides, it's only relevant if there are memory
cgroups with kmem accounting enabled. I don't think we can find a way to
handle this race w/o it, because alloc_page called from kmem_cache_alloc
may sleep so we can't flush all pending kmallocs w/o reference counting.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-12 16:56:38 -08:00
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2008-12-23 19:37:01 +09:00
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2011-02-25 11:38:54 -06:00
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2013-01-23 21:45:48 +00:00
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2015-02-10 14:09:32 -08:00
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2011-02-25 11:38:54 -06:00
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2015-02-10 14:09:32 -08:00
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2015-03-25 15:55:23 -07:00
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2015-02-10 14:09:32 -08:00
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2011-02-25 11:38:54 -06:00
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2009-12-18 16:26:20 -06:00
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2012-05-09 10:09:59 -05:00
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mm: slub: fix ALLOC_SLOWPATH stat
There used to be only one path out of __slab_alloc(), and ALLOC_SLOWPATH
got bumped in that exit path. Now there are two, and a bunch of gotos.
ALLOC_SLOWPATH can now get set more than once during a single call to
__slab_alloc() which is pretty bogus. Here's the sequence:
1. Enter __slab_alloc(), fall through all the way to the
stat(s, ALLOC_SLOWPATH);
2. hit 'if (!freelist)', and bump DEACTIVATE_BYPASS, jump to
new_slab (goto #1)
3. Hit 'if (c->partial)', bump CPU_PARTIAL_ALLOC, goto redo
(goto #2)
4. Fall through in the same path we did before all the way to
stat(s, ALLOC_SLOWPATH)
5. bump ALLOC_REFILL stat, then return
Doing this is obviously bogus. It keeps us from being able to
accurately compare ALLOC_SLOWPATH vs. ALLOC_FASTPATH. It also means
that the total number of allocs always exceeds the total number of
frees.
This patch moves stat(s, ALLOC_SLOWPATH) to be called from the same
place that __slab_alloc() is. This makes it much less likely that
ALLOC_SLOWPATH will get botched again in the spaghetti-code inside
__slab_alloc().
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:37 -07:00
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2007-10-16 01:26:05 -07:00
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|
mm: slub: fix ALLOC_SLOWPATH stat
There used to be only one path out of __slab_alloc(), and ALLOC_SLOWPATH
got bumped in that exit path. Now there are two, and a bunch of gotos.
ALLOC_SLOWPATH can now get set more than once during a single call to
__slab_alloc() which is pretty bogus. Here's the sequence:
1. Enter __slab_alloc(), fall through all the way to the
stat(s, ALLOC_SLOWPATH);
2. hit 'if (!freelist)', and bump DEACTIVATE_BYPASS, jump to
new_slab (goto #1)
3. Hit 'if (c->partial)', bump CPU_PARTIAL_ALLOC, goto redo
(goto #2)
4. Fall through in the same path we did before all the way to
stat(s, ALLOC_SLOWPATH)
5. bump ALLOC_REFILL stat, then return
Doing this is obviously bogus. It keeps us from being able to
accurately compare ALLOC_SLOWPATH vs. ALLOC_FASTPATH. It also means
that the total number of allocs always exceeds the total number of
frees.
This patch moves stat(s, ALLOC_SLOWPATH) to be called from the same
place that __slab_alloc() is. This makes it much less likely that
ALLOC_SLOWPATH will get botched again in the spaghetti-code inside
__slab_alloc().
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:06:37 -07:00
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slub: prefetch next freelist pointer in slab_alloc()
Recycling a page is a problem, since freelist link chain is hot on
cpu(s) which freed objects, and possibly very cold on cpu currently
owning slab.
Adding a prefetch of cache line containing the pointer to next object in
slab_alloc() helps a lot in many workloads, in particular on assymetric
ones (allocations done on one cpu, frees on another cpus). Added cost is
three machine instructions only.
Examples on my dual socket quad core ht machine (Intel CPU E5540
@2.53GHz) (16 logical cpus, 2 memory nodes), 64bit kernel.
Before patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
327577,471718 task-clock # 15,821 CPUs utilized ( +- 0,64% )
28 866 491 context-switches # 0,088 M/sec ( +- 1,80% )
1 506 929 CPU-migrations # 0,005 M/sec ( +- 3,24% )
127 151 page-faults # 0,000 M/sec ( +- 0,16% )
829 399 813 448 cycles # 2,532 GHz ( +- 0,64% )
580 664 691 740 stalled-cycles-frontend # 70,01% frontend cycles idle ( +- 0,71% )
197 431 700 448 stalled-cycles-backend # 23,80% backend cycles idle ( +- 1,03% )
503 548 648 975 instructions # 0,61 insns per cycle
# 1,15 stalled cycles per insn ( +- 0,46% )
95 780 068 471 branches # 292,389 M/sec ( +- 0,48% )
1 426 407 916 branch-misses # 1,49% of all branches ( +- 1,35% )
20,705679994 seconds time elapsed ( +- 0,64% )
After patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
286236,542804 task-clock # 15,786 CPUs utilized ( +- 1,32% )
19 703 372 context-switches # 0,069 M/sec ( +- 4,99% )
1 658 249 CPU-migrations # 0,006 M/sec ( +- 6,62% )
126 776 page-faults # 0,000 M/sec ( +- 0,12% )
724 636 593 213 cycles # 2,532 GHz ( +- 1,32% )
499 320 714 837 stalled-cycles-frontend # 68,91% frontend cycles idle ( +- 1,47% )
156 555 126 809 stalled-cycles-backend # 21,60% backend cycles idle ( +- 2,22% )
463 897 792 661 instructions # 0,64 insns per cycle
# 1,08 stalled cycles per insn ( +- 0,94% )
87 717 352 563 branches # 306,451 M/sec ( +- 0,99% )
941 738 280 branch-misses # 1,07% of all branches ( +- 3,35% )
18,132070670 seconds time elapsed ( +- 1,30% )
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Matt Mackall <mpm@selenic.com>
CC: David Rientjes <rientjes@google.com>
CC: "Alex,Shi" <alex.shi@intel.com>
CC: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-12-16 16:25:34 +01:00
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2011-02-25 11:38:54 -06:00
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2011-03-30 22:57:33 -03:00
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2011-02-25 11:38:54 -06:00
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2013-07-15 09:05:29 +08:00
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2011-02-25 11:38:54 -06:00
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2013-07-15 09:05:29 +08:00
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2011-02-25 11:38:54 -06:00
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2011-12-22 11:58:51 -06:00
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2011-02-25 11:38:54 -06:00
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slub: prefetch next freelist pointer in slab_alloc()
Recycling a page is a problem, since freelist link chain is hot on
cpu(s) which freed objects, and possibly very cold on cpu currently
owning slab.
Adding a prefetch of cache line containing the pointer to next object in
slab_alloc() helps a lot in many workloads, in particular on assymetric
ones (allocations done on one cpu, frees on another cpus). Added cost is
three machine instructions only.
Examples on my dual socket quad core ht machine (Intel CPU E5540
@2.53GHz) (16 logical cpus, 2 memory nodes), 64bit kernel.
Before patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
327577,471718 task-clock # 15,821 CPUs utilized ( +- 0,64% )
28 866 491 context-switches # 0,088 M/sec ( +- 1,80% )
1 506 929 CPU-migrations # 0,005 M/sec ( +- 3,24% )
127 151 page-faults # 0,000 M/sec ( +- 0,16% )
829 399 813 448 cycles # 2,532 GHz ( +- 0,64% )
580 664 691 740 stalled-cycles-frontend # 70,01% frontend cycles idle ( +- 0,71% )
197 431 700 448 stalled-cycles-backend # 23,80% backend cycles idle ( +- 1,03% )
503 548 648 975 instructions # 0,61 insns per cycle
# 1,15 stalled cycles per insn ( +- 0,46% )
95 780 068 471 branches # 292,389 M/sec ( +- 0,48% )
1 426 407 916 branch-misses # 1,49% of all branches ( +- 1,35% )
20,705679994 seconds time elapsed ( +- 0,64% )
After patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
286236,542804 task-clock # 15,786 CPUs utilized ( +- 1,32% )
19 703 372 context-switches # 0,069 M/sec ( +- 4,99% )
1 658 249 CPU-migrations # 0,006 M/sec ( +- 6,62% )
126 776 page-faults # 0,000 M/sec ( +- 0,12% )
724 636 593 213 cycles # 2,532 GHz ( +- 1,32% )
499 320 714 837 stalled-cycles-frontend # 68,91% frontend cycles idle ( +- 1,47% )
156 555 126 809 stalled-cycles-backend # 21,60% backend cycles idle ( +- 2,22% )
463 897 792 661 instructions # 0,64 insns per cycle
# 1,08 stalled cycles per insn ( +- 0,94% )
87 717 352 563 branches # 306,451 M/sec ( +- 0,99% )
941 738 280 branch-misses # 1,07% of all branches ( +- 3,35% )
18,132070670 seconds time elapsed ( +- 1,30% )
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Matt Mackall <mpm@selenic.com>
CC: David Rientjes <rientjes@google.com>
CC: "Alex,Shi" <alex.shi@intel.com>
CC: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-12-16 16:25:34 +01:00
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2011-02-25 11:38:54 -06:00
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slub: prefetch next freelist pointer in slab_alloc()
Recycling a page is a problem, since freelist link chain is hot on
cpu(s) which freed objects, and possibly very cold on cpu currently
owning slab.
Adding a prefetch of cache line containing the pointer to next object in
slab_alloc() helps a lot in many workloads, in particular on assymetric
ones (allocations done on one cpu, frees on another cpus). Added cost is
three machine instructions only.
Examples on my dual socket quad core ht machine (Intel CPU E5540
@2.53GHz) (16 logical cpus, 2 memory nodes), 64bit kernel.
Before patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
327577,471718 task-clock # 15,821 CPUs utilized ( +- 0,64% )
28 866 491 context-switches # 0,088 M/sec ( +- 1,80% )
1 506 929 CPU-migrations # 0,005 M/sec ( +- 3,24% )
127 151 page-faults # 0,000 M/sec ( +- 0,16% )
829 399 813 448 cycles # 2,532 GHz ( +- 0,64% )
580 664 691 740 stalled-cycles-frontend # 70,01% frontend cycles idle ( +- 0,71% )
197 431 700 448 stalled-cycles-backend # 23,80% backend cycles idle ( +- 1,03% )
503 548 648 975 instructions # 0,61 insns per cycle
# 1,15 stalled cycles per insn ( +- 0,46% )
95 780 068 471 branches # 292,389 M/sec ( +- 0,48% )
1 426 407 916 branch-misses # 1,49% of all branches ( +- 1,35% )
20,705679994 seconds time elapsed ( +- 0,64% )
After patch :
# perf stat -r 32 hackbench 50 process 4000 >/dev/null
Performance counter stats for 'hackbench 50 process 4000' (32 runs):
286236,542804 task-clock # 15,786 CPUs utilized ( +- 1,32% )
19 703 372 context-switches # 0,069 M/sec ( +- 4,99% )
1 658 249 CPU-migrations # 0,006 M/sec ( +- 6,62% )
126 776 page-faults # 0,000 M/sec ( +- 0,12% )
724 636 593 213 cycles # 2,532 GHz ( +- 1,32% )
499 320 714 837 stalled-cycles-frontend # 68,91% frontend cycles idle ( +- 1,47% )
156 555 126 809 stalled-cycles-backend # 21,60% backend cycles idle ( +- 2,22% )
463 897 792 661 instructions # 0,64 insns per cycle
# 1,08 stalled cycles per insn ( +- 0,94% )
87 717 352 563 branches # 306,451 M/sec ( +- 0,99% )
941 738 280 branch-misses # 1,07% of all branches ( +- 3,35% )
18,132070670 seconds time elapsed ( +- 1,30% )
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Matt Mackall <mpm@selenic.com>
CC: David Rientjes <rientjes@google.com>
CC: "Alex,Shi" <alex.shi@intel.com>
CC: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-12-16 16:25:34 +01:00
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2009-12-18 16:26:23 -06:00
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2007-05-10 03:15:16 -07:00
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mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
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2011-02-25 11:38:54 -06:00
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mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
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2012-06-13 10:24:57 -05:00
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2007-07-17 04:03:23 -07:00
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2015-11-20 15:57:52 -08:00
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2008-04-04 00:54:48 +02:00
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2007-05-10 03:15:16 -07:00
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2007-05-06 14:49:36 -07:00
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2012-09-08 17:47:58 -03:00
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2007-05-06 14:49:36 -07:00
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2012-09-08 17:47:58 -03:00
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2008-08-19 20:43:26 +03:00
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2013-07-15 09:05:29 +08:00
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2008-08-19 20:43:26 +03:00
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2007-05-06 14:49:36 -07:00
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2009-12-11 15:45:30 +08:00
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2010-10-21 10:29:19 +01:00
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2008-08-19 20:43:26 +03:00
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2012-09-08 17:47:58 -03:00
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2010-10-21 10:29:19 +01:00
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kasan, mm: change hooks signatures
Patch series "kasan: add software tag-based mode for arm64", v13.
This patchset adds a new software tag-based mode to KASAN [1]. (Initially
this mode was called KHWASAN, but it got renamed, see the naming rationale
at the end of this section).
The plan is to implement HWASan [2] for the kernel with the incentive,
that it's going to have comparable to KASAN performance, but in the same
time consume much less memory, trading that off for somewhat imprecise bug
detection and being supported only for arm64.
The underlying ideas of the approach used by software tag-based KASAN are:
1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store
pointer tags in the top byte of each kernel pointer.
2. Using shadow memory, we can store memory tags for each chunk of kernel
memory.
3. On each memory allocation, we can generate a random tag, embed it into
the returned pointer and set the memory tags that correspond to this
chunk of memory to the same value.
4. By using compiler instrumentation, before each memory access we can add
a check that the pointer tag matches the tag of the memory that is being
accessed.
5. On a tag mismatch we report an error.
With this patchset the existing KASAN mode gets renamed to generic KASAN,
with the word "generic" meaning that the implementation can be supported
by any architecture as it is purely software.
The new mode this patchset adds is called software tag-based KASAN. The
word "tag-based" refers to the fact that this mode uses tags embedded into
the top byte of kernel pointers and the TBI arm64 CPU feature that allows
to dereference such pointers. The word "software" here means that shadow
memory manipulation and tag checking on pointer dereference is done in
software. As it is the only tag-based implementation right now, "software
tag-based" KASAN is sometimes referred to as simply "tag-based" in this
patchset.
A potential expansion of this mode is a hardware tag-based mode, which
would use hardware memory tagging support (announced by Arm [3]) instead
of compiler instrumentation and manual shadow memory manipulation.
Same as generic KASAN, software tag-based KASAN is strictly a debugging
feature.
[1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html
[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a
====== Rationale
On mobile devices generic KASAN's memory usage is significant problem.
One of the main reasons to have tag-based KASAN is to be able to perform a
similar set of checks as the generic one does, but with lower memory
requirements.
Comment from Vishwath Mohan <vishwath@google.com>:
I don't have data on-hand, but anecdotally both ASAN and KASAN have proven
problematic to enable for environments that don't tolerate the increased
memory pressure well. This includes
(a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go,
(c) Connected components like Pixel's visual core [1].
These are both places I'd love to have a low(er) memory footprint option at
my disposal.
Comment from Evgenii Stepanov <eugenis@google.com>:
Looking at a live Android device under load, slab (according to
/proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's
overhead of 2x - 3x on top of it is not insignificant.
Not having this overhead enables near-production use - ex. running
KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do
not reproduce in test configuration. These are the ones that often cost
the most engineering time to track down.
CPU overhead is bad, but generally tolerable. RAM is critical, in our
experience. Once it gets low enough, OOM-killer makes your life
miserable.
[1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/
====== Technical details
Software tag-based KASAN mode is implemented in a very similar way to the
generic one. This patchset essentially does the following:
1. TCR_TBI1 is set to enable Top Byte Ignore.
2. Shadow memory is used (with a different scale, 1:16, so each shadow
byte corresponds to 16 bytes of kernel memory) to store memory tags.
3. All slab objects are aligned to shadow scale, which is 16 bytes.
4. All pointers returned from the slab allocator are tagged with a random
tag and the corresponding shadow memory is poisoned with the same value.
5. Compiler instrumentation is used to insert tag checks. Either by
calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and
CONFIG_KASAN_INLINE flags are reused).
6. When a tag mismatch is detected in callback instrumentation mode
KASAN simply prints a bug report. In case of inline instrumentation,
clang inserts a brk instruction, and KASAN has it's own brk handler,
which reports the bug.
7. The memory in between slab objects is marked with a reserved tag, and
acts as a redzone.
8. When a slab object is freed it's marked with a reserved tag.
Bug detection is imprecise for two reasons:
1. We won't catch some small out-of-bounds accesses, that fall into the
same shadow cell, as the last byte of a slab object.
2. We only have 1 byte to store tags, which means we have a 1/256
probability of a tag match for an incorrect access (actually even
slightly less due to reserved tag values).
Despite that there's a particular type of bugs that tag-based KASAN can
detect compared to generic KASAN: use-after-free after the object has been
allocated by someone else.
====== Testing
Some kernel developers voiced a concern that changing the top byte of
kernel pointers may lead to subtle bugs that are difficult to discover.
To address this concern deliberate testing has been performed.
It doesn't seem feasible to do some kind of static checking to find
potential issues with pointer tagging, so a dynamic approach was taken.
All pointer comparisons/subtractions have been instrumented in an LLVM
compiler pass and a kernel module that would print a bug report whenever
two pointers with different tags are being compared/subtracted (ignoring
comparisons with NULL pointers and with pointers obtained by casting an
error code to a pointer type) has been used. Then the kernel has been
booted in QEMU and on an Odroid C2 board and syzkaller has been run.
This yielded the following results.
The two places that look interesting are:
is_vmalloc_addr in include/linux/mm.h
is_kernel_rodata in mm/util.c
Here we compare a pointer with some fixed untagged values to make sure
that the pointer lies in a particular part of the kernel address space.
Since tag-based KASAN doesn't add tags to pointers that belong to rodata
or vmalloc regions, this should work as is. To make sure debug checks to
those two functions that check that the result doesn't change whether we
operate on pointers with or without untagging has been added.
A few other cases that don't look that interesting:
Comparing pointers to achieve unique sorting order of pointee objects
(e.g. sorting locks addresses before performing a double lock):
tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c
pipe_double_lock in fs/pipe.c
unix_state_double_lock in net/unix/af_unix.c
lock_two_nondirectories in fs/inode.c
mutex_lock_double in kernel/events/core.c
ep_cmp_ffd in fs/eventpoll.c
fsnotify_compare_groups fs/notify/mark.c
Nothing needs to be done here, since the tags embedded into pointers
don't change, so the sorting order would still be unique.
Checks that a pointer belongs to some particular allocation:
is_sibling_entry in lib/radix-tree.c
object_is_on_stack in include/linux/sched/task_stack.h
Nothing needs to be done here either, since two pointers can only belong
to the same allocation if they have the same tag.
Overall, since the kernel boots and works, there are no critical bugs.
As for the rest, the traditional kernel testing way (use until fails) is
the only one that looks feasible.
Another point here is that tag-based KASAN is available under a separate
config option that needs to be deliberately enabled. Even though it might
be used in a "near-production" environment to find bugs that are not found
during fuzzing or running tests, it is still a debug tool.
====== Benchmarks
The following numbers were collected on Odroid C2 board. Both generic and
tag-based KASAN were used in inline instrumentation mode.
Boot time [1]:
* ~1.7 sec for clean kernel
* ~5.0 sec for generic KASAN
* ~5.0 sec for tag-based KASAN
Network performance [2]:
* 8.33 Gbits/sec for clean kernel
* 3.17 Gbits/sec for generic KASAN
* 2.85 Gbits/sec for tag-based KASAN
Slab memory usage after boot [3]:
* ~40 kb for clean kernel
* ~105 kb (~260% overhead) for generic KASAN
* ~47 kb (~20% overhead) for tag-based KASAN
KASAN memory overhead consists of three main parts:
1. Increased slab memory usage due to redzones.
2. Shadow memory (the whole reserved once during boot).
3. Quaratine (grows gradually until some preset limit; the more the limit,
the more the chance to detect a use-after-free).
Comparing tag-based vs generic KASAN for each of these points:
1. 20% vs 260% overhead.
2. 1/16th vs 1/8th of physical memory.
3. Tag-based KASAN doesn't require quarantine.
[1] Time before the ext4 driver is initialized.
[2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
[3] Measured as `cat /proc/meminfo | grep Slab`.
====== Some notes
A few notes:
1. The patchset can be found here:
https://github.com/xairy/kasan-prototype/tree/khwasan
2. Building requires a recent Clang version (7.0.0 or later).
3. Stack instrumentation is not supported yet and will be added later.
This patch (of 25):
Tag-based KASAN changes the value of the top byte of pointers returned
from the kernel allocation functions (such as kmalloc). This patch
updates KASAN hooks signatures and their usage in SLAB and SLUB code to
reflect that.
Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 00:29:37 -08:00
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2010-10-21 10:29:19 +01:00
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2008-08-19 20:43:26 +03:00
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2010-10-21 10:29:19 +01:00
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2008-08-19 20:43:26 +03:00
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2007-05-06 14:49:36 -07:00
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2012-09-08 17:47:58 -03:00
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2008-08-19 20:43:26 +03:00
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2009-03-23 15:12:24 +02:00
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2012-06-13 10:24:57 -05:00
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2008-08-19 20:43:26 +03:00
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2007-05-06 14:49:36 -07:00
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2009-12-11 15:45:30 +08:00
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2010-10-21 10:29:19 +01:00
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2008-08-19 20:43:26 +03:00
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2010-10-21 10:29:19 +01:00
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2008-08-19 20:43:26 +03:00
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2012-09-08 17:47:58 -03:00
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2010-10-21 10:29:19 +01:00
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2015-02-13 14:39:42 -08:00
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kasan, mm: change hooks signatures
Patch series "kasan: add software tag-based mode for arm64", v13.
This patchset adds a new software tag-based mode to KASAN [1]. (Initially
this mode was called KHWASAN, but it got renamed, see the naming rationale
at the end of this section).
The plan is to implement HWASan [2] for the kernel with the incentive,
that it's going to have comparable to KASAN performance, but in the same
time consume much less memory, trading that off for somewhat imprecise bug
detection and being supported only for arm64.
The underlying ideas of the approach used by software tag-based KASAN are:
1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store
pointer tags in the top byte of each kernel pointer.
2. Using shadow memory, we can store memory tags for each chunk of kernel
memory.
3. On each memory allocation, we can generate a random tag, embed it into
the returned pointer and set the memory tags that correspond to this
chunk of memory to the same value.
4. By using compiler instrumentation, before each memory access we can add
a check that the pointer tag matches the tag of the memory that is being
accessed.
5. On a tag mismatch we report an error.
With this patchset the existing KASAN mode gets renamed to generic KASAN,
with the word "generic" meaning that the implementation can be supported
by any architecture as it is purely software.
The new mode this patchset adds is called software tag-based KASAN. The
word "tag-based" refers to the fact that this mode uses tags embedded into
the top byte of kernel pointers and the TBI arm64 CPU feature that allows
to dereference such pointers. The word "software" here means that shadow
memory manipulation and tag checking on pointer dereference is done in
software. As it is the only tag-based implementation right now, "software
tag-based" KASAN is sometimes referred to as simply "tag-based" in this
patchset.
A potential expansion of this mode is a hardware tag-based mode, which
would use hardware memory tagging support (announced by Arm [3]) instead
of compiler instrumentation and manual shadow memory manipulation.
Same as generic KASAN, software tag-based KASAN is strictly a debugging
feature.
[1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html
[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a
====== Rationale
On mobile devices generic KASAN's memory usage is significant problem.
One of the main reasons to have tag-based KASAN is to be able to perform a
similar set of checks as the generic one does, but with lower memory
requirements.
Comment from Vishwath Mohan <vishwath@google.com>:
I don't have data on-hand, but anecdotally both ASAN and KASAN have proven
problematic to enable for environments that don't tolerate the increased
memory pressure well. This includes
(a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go,
(c) Connected components like Pixel's visual core [1].
These are both places I'd love to have a low(er) memory footprint option at
my disposal.
Comment from Evgenii Stepanov <eugenis@google.com>:
Looking at a live Android device under load, slab (according to
/proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's
overhead of 2x - 3x on top of it is not insignificant.
Not having this overhead enables near-production use - ex. running
KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do
not reproduce in test configuration. These are the ones that often cost
the most engineering time to track down.
CPU overhead is bad, but generally tolerable. RAM is critical, in our
experience. Once it gets low enough, OOM-killer makes your life
miserable.
[1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/
====== Technical details
Software tag-based KASAN mode is implemented in a very similar way to the
generic one. This patchset essentially does the following:
1. TCR_TBI1 is set to enable Top Byte Ignore.
2. Shadow memory is used (with a different scale, 1:16, so each shadow
byte corresponds to 16 bytes of kernel memory) to store memory tags.
3. All slab objects are aligned to shadow scale, which is 16 bytes.
4. All pointers returned from the slab allocator are tagged with a random
tag and the corresponding shadow memory is poisoned with the same value.
5. Compiler instrumentation is used to insert tag checks. Either by
calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and
CONFIG_KASAN_INLINE flags are reused).
6. When a tag mismatch is detected in callback instrumentation mode
KASAN simply prints a bug report. In case of inline instrumentation,
clang inserts a brk instruction, and KASAN has it's own brk handler,
which reports the bug.
7. The memory in between slab objects is marked with a reserved tag, and
acts as a redzone.
8. When a slab object is freed it's marked with a reserved tag.
Bug detection is imprecise for two reasons:
1. We won't catch some small out-of-bounds accesses, that fall into the
same shadow cell, as the last byte of a slab object.
2. We only have 1 byte to store tags, which means we have a 1/256
probability of a tag match for an incorrect access (actually even
slightly less due to reserved tag values).
Despite that there's a particular type of bugs that tag-based KASAN can
detect compared to generic KASAN: use-after-free after the object has been
allocated by someone else.
====== Testing
Some kernel developers voiced a concern that changing the top byte of
kernel pointers may lead to subtle bugs that are difficult to discover.
To address this concern deliberate testing has been performed.
It doesn't seem feasible to do some kind of static checking to find
potential issues with pointer tagging, so a dynamic approach was taken.
All pointer comparisons/subtractions have been instrumented in an LLVM
compiler pass and a kernel module that would print a bug report whenever
two pointers with different tags are being compared/subtracted (ignoring
comparisons with NULL pointers and with pointers obtained by casting an
error code to a pointer type) has been used. Then the kernel has been
booted in QEMU and on an Odroid C2 board and syzkaller has been run.
This yielded the following results.
The two places that look interesting are:
is_vmalloc_addr in include/linux/mm.h
is_kernel_rodata in mm/util.c
Here we compare a pointer with some fixed untagged values to make sure
that the pointer lies in a particular part of the kernel address space.
Since tag-based KASAN doesn't add tags to pointers that belong to rodata
or vmalloc regions, this should work as is. To make sure debug checks to
those two functions that check that the result doesn't change whether we
operate on pointers with or without untagging has been added.
A few other cases that don't look that interesting:
Comparing pointers to achieve unique sorting order of pointee objects
(e.g. sorting locks addresses before performing a double lock):
tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c
pipe_double_lock in fs/pipe.c
unix_state_double_lock in net/unix/af_unix.c
lock_two_nondirectories in fs/inode.c
mutex_lock_double in kernel/events/core.c
ep_cmp_ffd in fs/eventpoll.c
fsnotify_compare_groups fs/notify/mark.c
Nothing needs to be done here, since the tags embedded into pointers
don't change, so the sorting order would still be unique.
Checks that a pointer belongs to some particular allocation:
is_sibling_entry in lib/radix-tree.c
object_is_on_stack in include/linux/sched/task_stack.h
Nothing needs to be done here either, since two pointers can only belong
to the same allocation if they have the same tag.
Overall, since the kernel boots and works, there are no critical bugs.
As for the rest, the traditional kernel testing way (use until fails) is
the only one that looks feasible.
Another point here is that tag-based KASAN is available under a separate
config option that needs to be deliberately enabled. Even though it might
be used in a "near-production" environment to find bugs that are not found
during fuzzing or running tests, it is still a debug tool.
====== Benchmarks
The following numbers were collected on Odroid C2 board. Both generic and
tag-based KASAN were used in inline instrumentation mode.
Boot time [1]:
* ~1.7 sec for clean kernel
* ~5.0 sec for generic KASAN
* ~5.0 sec for tag-based KASAN
Network performance [2]:
* 8.33 Gbits/sec for clean kernel
* 3.17 Gbits/sec for generic KASAN
* 2.85 Gbits/sec for tag-based KASAN
Slab memory usage after boot [3]:
* ~40 kb for clean kernel
* ~105 kb (~260% overhead) for generic KASAN
* ~47 kb (~20% overhead) for tag-based KASAN
KASAN memory overhead consists of three main parts:
1. Increased slab memory usage due to redzones.
2. Shadow memory (the whole reserved once during boot).
3. Quaratine (grows gradually until some preset limit; the more the limit,
the more the chance to detect a use-after-free).
Comparing tag-based vs generic KASAN for each of these points:
1. 20% vs 260% overhead.
2. 1/16th vs 1/8th of physical memory.
3. Tag-based KASAN doesn't require quarantine.
[1] Time before the ext4 driver is initialized.
[2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
[3] Measured as `cat /proc/meminfo | grep Slab`.
====== Some notes
A few notes:
1. The patchset can be found here:
https://github.com/xairy/kasan-prototype/tree/khwasan
2. Building requires a recent Clang version (7.0.0 or later).
3. Stack instrumentation is not supported yet and will be added later.
This patch (of 25):
Tag-based KASAN changes the value of the top byte of pointers returned
from the kernel allocation functions (such as kmalloc). This patch
updates KASAN hooks signatures and their usage in SLAB and SLUB code to
reflect that.
Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 00:29:37 -08:00
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2010-10-21 10:29:19 +01:00
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2008-08-19 20:43:26 +03:00
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2010-10-21 10:29:19 +01:00
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2008-08-19 20:43:26 +03:00
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2019-05-13 17:16:09 -07:00
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2008-08-19 20:43:26 +03:00
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2007-05-06 14:49:36 -07:00
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2015-02-10 14:09:37 -08:00
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2007-05-10 03:15:16 -07:00
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2011-02-25 11:38:54 -06:00
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2012-05-30 12:54:46 -05:00
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2016-03-15 14:54:59 -07:00
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2011-06-01 12:25:55 -05:00
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2008-02-15 23:45:26 -08:00
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2011-06-01 12:25:52 -05:00
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slub: remove one code path and reduce lock contention in __slab_free()
When we try to free object, there is some of case that we need
to take a node lock. This is the necessary step for preventing a race.
After taking a lock, then we try to cmpxchg_double_slab().
But, there is a possible scenario that cmpxchg_double_slab() is failed
with taking a lock. Following example explains it.
CPU A CPU B
need lock
... need lock
... lock!!
lock..but spin free success
spin... unlock
lock!!
free fail
In this case, retry with taking a lock is occured in CPU A.
I think that in this case for CPU A,
"release a lock first, and re-take a lock if necessary" is preferable way.
There are two reasons for this.
First, this makes __slab_free()'s logic somehow simple.
With this patch, 'was_frozen = 1' is "always" handled without taking a lock.
So we can remove one code path.
Second, it may reduce lock contention.
When we do retrying, status of slab is already changed,
so we don't need a lock anymore in almost every case.
"release a lock first, and re-take a lock if necessary" policy is
helpful to this.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-08-16 00:02:40 +09:00
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2011-06-01 12:25:52 -05:00
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2015-11-20 15:57:46 -08:00
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2011-06-01 12:25:52 -05:00
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2015-11-20 15:57:46 -08:00
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slub: remove one code path and reduce lock contention in __slab_free()
When we try to free object, there is some of case that we need
to take a node lock. This is the necessary step for preventing a race.
After taking a lock, then we try to cmpxchg_double_slab().
But, there is a possible scenario that cmpxchg_double_slab() is failed
with taking a lock. Following example explains it.
CPU A CPU B
need lock
... need lock
... lock!!
lock..but spin free success
spin... unlock
lock!!
free fail
In this case, retry with taking a lock is occured in CPU A.
I think that in this case for CPU A,
"release a lock first, and re-take a lock if necessary" is preferable way.
There are two reasons for this.
First, this makes __slab_free()'s logic somehow simple.
With this patch, 'was_frozen = 1' is "always" handled without taking a lock.
So we can remove one code path.
Second, it may reduce lock contention.
When we do retrying, status of slab is already changed,
so we don't need a lock anymore in almost every case.
"release a lock first, and re-take a lock if necessary" policy is
helpful to this.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-08-16 00:02:40 +09:00
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2011-08-09 16:12:27 -05:00
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2014-01-10 13:23:49 +01:00
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2011-08-09 16:12:27 -05:00
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2013-07-15 09:05:29 +08:00
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2011-08-09 16:12:27 -05:00
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2014-01-10 13:23:49 +01:00
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2011-08-09 16:12:27 -05:00
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2014-12-10 15:42:13 -08:00
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2011-08-09 16:12:27 -05:00
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2011-06-01 12:25:52 -05:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:52 -05:00
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2015-11-20 15:57:46 -08:00
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2011-06-01 12:25:52 -05:00
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2011-06-01 12:25:52 -05:00
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2011-08-09 16:12:27 -05:00
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2012-02-03 23:34:56 +08:00
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2011-08-09 16:12:27 -05:00
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2012-02-03 23:34:56 +08:00
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2011-08-09 16:12:27 -05:00
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2007-05-06 14:49:36 -07:00
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2014-07-02 15:22:35 -07:00
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slub: remove one code path and reduce lock contention in __slab_free()
When we try to free object, there is some of case that we need
to take a node lock. This is the necessary step for preventing a race.
After taking a lock, then we try to cmpxchg_double_slab().
But, there is a possible scenario that cmpxchg_double_slab() is failed
with taking a lock. Following example explains it.
CPU A CPU B
need lock
... need lock
... lock!!
lock..but spin free success
spin... unlock
lock!!
free fail
In this case, retry with taking a lock is occured in CPU A.
I think that in this case for CPU A,
"release a lock first, and re-take a lock if necessary" is preferable way.
There are two reasons for this.
First, this makes __slab_free()'s logic somehow simple.
With this patch, 'was_frozen = 1' is "always" handled without taking a lock.
So we can remove one code path.
Second, it may reduce lock contention.
When we do retrying, status of slab is already changed,
so we don't need a lock anymore in almost every case.
"release a lock first, and re-take a lock if necessary" policy is
helpful to this.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-08-16 00:02:40 +09:00
|
|
|
|
2007-05-06 14:49:36 -07:00
|
|
|
|
slub: remove one code path and reduce lock contention in __slab_free()
When we try to free object, there is some of case that we need
to take a node lock. This is the necessary step for preventing a race.
After taking a lock, then we try to cmpxchg_double_slab().
But, there is a possible scenario that cmpxchg_double_slab() is failed
with taking a lock. Following example explains it.
CPU A CPU B
need lock
... need lock
... lock!!
lock..but spin free success
spin... unlock
lock!!
free fail
In this case, retry with taking a lock is occured in CPU A.
I think that in this case for CPU A,
"release a lock first, and re-take a lock if necessary" is preferable way.
There are two reasons for this.
First, this makes __slab_free()'s logic somehow simple.
With this patch, 'was_frozen = 1' is "always" handled without taking a lock.
So we can remove one code path.
Second, it may reduce lock contention.
When we do retrying, status of slab is already changed,
so we don't need a lock anymore in almost every case.
"release a lock first, and re-take a lock if necessary" policy is
helpful to this.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-08-16 00:02:40 +09:00
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2013-06-19 14:05:52 +09:00
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2019-05-13 17:16:22 -07:00
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slub: remove one code path and reduce lock contention in __slab_free()
When we try to free object, there is some of case that we need
to take a node lock. This is the necessary step for preventing a race.
After taking a lock, then we try to cmpxchg_double_slab().
But, there is a possible scenario that cmpxchg_double_slab() is failed
with taking a lock. Following example explains it.
CPU A CPU B
need lock
... need lock
... lock!!
lock..but spin free success
spin... unlock
lock!!
free fail
In this case, retry with taking a lock is occured in CPU A.
I think that in this case for CPU A,
"release a lock first, and re-take a lock if necessary" is preferable way.
There are two reasons for this.
First, this makes __slab_free()'s logic somehow simple.
With this patch, 'was_frozen = 1' is "always" handled without taking a lock.
So we can remove one code path.
Second, it may reduce lock contention.
When we do retrying, status of slab is already changed,
so we don't need a lock anymore in almost every case.
"release a lock first, and re-take a lock if necessary" policy is
helpful to this.
Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-08-16 00:02:40 +09:00
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2008-02-07 17:47:41 -08:00
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2011-06-01 12:25:55 -05:00
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2007-05-06 14:49:36 -07:00
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2008-03-01 13:40:44 -08:00
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2007-05-06 14:49:36 -07:00
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2011-08-08 11:16:56 -05:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:50 -05:00
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2009-12-18 16:26:23 -06:00
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2014-01-10 13:23:49 +01:00
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2011-08-08 11:16:56 -05:00
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2014-01-10 13:23:49 +01:00
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2011-06-01 12:25:52 -05:00
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2011-06-01 12:25:55 -05:00
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2009-12-18 16:26:23 -06:00
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2007-05-06 14:49:36 -07:00
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2007-05-10 03:15:16 -07:00
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2015-11-20 15:57:46 -08:00
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2007-05-10 03:15:16 -07:00
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2016-07-28 15:49:07 -07:00
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2007-05-10 03:15:16 -07:00
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2015-11-20 15:57:46 -08:00
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2007-10-16 01:26:05 -07:00
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2011-02-25 11:38:54 -06:00
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2011-03-15 12:45:21 -05:00
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2011-02-25 11:38:54 -06:00
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2015-09-04 15:45:31 -07:00
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2011-02-25 11:38:54 -06:00
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2015-02-10 14:09:32 -08:00
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2015-03-25 15:55:23 -07:00
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2010-08-20 12:37:16 -05:00
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2015-02-10 14:09:32 -08:00
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2010-08-20 12:37:16 -05:00
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2011-05-17 16:29:31 -05:00
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2015-11-20 15:57:46 -08:00
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2011-02-25 11:38:54 -06:00
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2011-12-22 11:58:51 -06:00
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2011-02-25 11:38:54 -06:00
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2015-11-20 15:57:46 -08:00
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2011-02-25 11:38:54 -06:00
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2009-12-18 16:26:23 -06:00
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2007-05-10 03:15:16 -07:00
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2015-11-20 15:57:46 -08:00
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2007-05-10 03:15:16 -07:00
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2016-07-28 15:49:07 -07:00
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2018-04-10 16:30:31 -07:00
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2016-07-28 15:49:07 -07:00
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2018-04-10 16:30:31 -07:00
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2016-07-28 15:49:07 -07:00
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2018-12-28 00:29:53 -08:00
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2016-07-28 15:49:07 -07:00
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2007-05-06 14:49:36 -07:00
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2012-12-18 14:22:46 -08:00
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2012-09-04 23:06:14 +00:00
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2015-11-20 15:57:46 -08:00
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2009-03-23 15:12:24 +02:00
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2007-05-06 14:49:36 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2016-03-15 14:53:32 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2016-03-15 14:53:32 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2016-03-15 14:54:00 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2016-03-15 14:54:00 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2016-03-15 14:54:00 -07:00
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mm: charge/uncharge kmemcg from generic page allocator paths
Currently, to charge a non-slab allocation to kmemcg one has to use
alloc_kmem_pages helper with __GFP_ACCOUNT flag. A page allocated with
this helper should finally be freed using free_kmem_pages, otherwise it
won't be uncharged.
This API suits its current users fine, but it turns out to be impossible
to use along with page reference counting, i.e. when an allocation is
supposed to be freed with put_page, as it is the case with pipe or unix
socket buffers.
To overcome this limitation, this patch moves charging/uncharging to
generic page allocator paths, i.e. to __alloc_pages_nodemask and
free_pages_prepare, and zaps alloc/free_kmem_pages helpers. This way,
one can use any of the available page allocation functions to get the
allocated page charged to kmemcg - it's enough to pass __GFP_ACCOUNT,
just like in case of kmalloc and friends. A charged page will be
automatically uncharged on free.
To make it possible, we need to mark pages charged to kmemcg somehow.
To avoid introducing a new page flag, we make use of page->_mapcount for
marking such pages. Since pages charged to kmemcg are not supposed to
be mapped to userspace, it should work just fine. There are other
(ab)users of page->_mapcount - buddy and balloon pages - but we don't
conflict with them.
In case kmemcg is compiled out or not used at runtime, this patch
introduces no overhead to generic page allocator paths. If kmemcg is
used, it will be plus one gfp flags check on alloc and plus one
page->_mapcount check on free, which shouldn't hurt performance, because
the data accessed are hot.
Link: http://lkml.kernel.org/r/a9736d856f895bcb465d9f257b54efe32eda6f99.1464079538.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 15:24:24 -07:00
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2016-03-15 14:54:00 -07:00
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2016-03-15 14:53:32 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2016-03-15 14:54:00 -07:00
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2016-03-15 14:53:32 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2016-03-15 14:53:32 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2015-09-04 15:45:37 -07:00
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2016-03-15 14:53:32 -07:00
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2015-09-04 15:45:34 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2015-09-04 15:45:43 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2015-09-04 15:45:43 -07:00
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slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
|
|
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|
2016-12-12 16:41:35 -08:00
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|
slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
|
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|
2015-09-04 15:45:43 -07:00
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2016-03-15 14:53:32 -07:00
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|
slub: optimize bulk slowpath free by detached freelist
This change focus on improving the speed of object freeing in the
"slowpath" of kmem_cache_free_bulk.
The calls slab_free (fastpath) and __slab_free (slowpath) have been
extended with support for bulk free, which amortize the overhead of
the (locked) cmpxchg_double.
To use the new bulking feature, we build what I call a detached
freelist. The detached freelist takes advantage of three properties:
1) the free function call owns the object that is about to be freed,
thus writing into this memory is synchronization-free.
2) many freelist's can co-exist side-by-side in the same slab-page
each with a separate head pointer.
3) it is the visibility of the head pointer that needs synchronization.
Given these properties, the brilliant part is that the detached
freelist can be constructed without any need for synchronization. The
freelist is constructed directly in the page objects, without any
synchronization needed. The detached freelist is allocated on the
stack of the function call kmem_cache_free_bulk. Thus, the freelist
head pointer is not visible to other CPUs.
All objects in a SLUB freelist must belong to the same slab-page.
Thus, constructing the detached freelist is about matching objects
that belong to the same slab-page. The bulk free array is scanned is
a progressive manor with a limited look-ahead facility.
Kmem debug support is handled in call of slab_free().
Notice kmem_cache_free_bulk no longer need to disable IRQs. This
only slowed down single free bulk with approx 3 cycles.
Performance data:
Benchmarked[1] obj size 256 bytes on CPU i7-4790K @ 4.00GHz
SLUB fastpath single object quick reuse: 47 cycles(tsc) 11.931 ns
To get stable and comparable numbers, the kernel have been booted with
"slab_merge" (this also improve performance for larger bulk sizes).
Performance data, compared against fallback bulking:
bulk - fallback bulk - improvement with this patch
1 - 62 cycles(tsc) 15.662 ns - 49 cycles(tsc) 12.407 ns- improved 21.0%
2 - 55 cycles(tsc) 13.935 ns - 30 cycles(tsc) 7.506 ns - improved 45.5%
3 - 53 cycles(tsc) 13.341 ns - 23 cycles(tsc) 5.865 ns - improved 56.6%
4 - 52 cycles(tsc) 13.081 ns - 20 cycles(tsc) 5.048 ns - improved 61.5%
8 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.659 ns - improved 64.0%
16 - 49 cycles(tsc) 12.412 ns - 17 cycles(tsc) 4.495 ns - improved 65.3%
30 - 49 cycles(tsc) 12.484 ns - 18 cycles(tsc) 4.533 ns - improved 63.3%
32 - 50 cycles(tsc) 12.627 ns - 18 cycles(tsc) 4.707 ns - improved 64.0%
34 - 96 cycles(tsc) 24.243 ns - 23 cycles(tsc) 5.976 ns - improved 76.0%
48 - 83 cycles(tsc) 20.818 ns - 21 cycles(tsc) 5.329 ns - improved 74.7%
64 - 74 cycles(tsc) 18.700 ns - 20 cycles(tsc) 5.127 ns - improved 73.0%
128 - 90 cycles(tsc) 22.734 ns - 27 cycles(tsc) 6.833 ns - improved 70.0%
158 - 99 cycles(tsc) 24.776 ns - 30 cycles(tsc) 7.583 ns - improved 69.7%
250 - 104 cycles(tsc) 26.089 ns - 37 cycles(tsc) 9.280 ns - improved 64.4%
Performance data, compared current in-kernel bulking:
bulk - curr in-kernel - improvement with this patch
1 - 46 cycles(tsc) - 49 cycles(tsc) - improved (cycles:-3) -6.5%
2 - 27 cycles(tsc) - 30 cycles(tsc) - improved (cycles:-3) -11.1%
3 - 21 cycles(tsc) - 23 cycles(tsc) - improved (cycles:-2) -9.5%
4 - 18 cycles(tsc) - 20 cycles(tsc) - improved (cycles:-2) -11.1%
8 - 17 cycles(tsc) - 18 cycles(tsc) - improved (cycles:-1) -5.9%
16 - 18 cycles(tsc) - 17 cycles(tsc) - improved (cycles: 1) 5.6%
30 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
32 - 18 cycles(tsc) - 18 cycles(tsc) - improved (cycles: 0) 0.0%
34 - 78 cycles(tsc) - 23 cycles(tsc) - improved (cycles:55) 70.5%
48 - 60 cycles(tsc) - 21 cycles(tsc) - improved (cycles:39) 65.0%
64 - 49 cycles(tsc) - 20 cycles(tsc) - improved (cycles:29) 59.2%
128 - 69 cycles(tsc) - 27 cycles(tsc) - improved (cycles:42) 60.9%
158 - 79 cycles(tsc) - 30 cycles(tsc) - improved (cycles:49) 62.0%
250 - 86 cycles(tsc) - 37 cycles(tsc) - improved (cycles:49) 57.0%
Performance with normal SLUB merging is significantly slower for
larger bulking. This is believed to (primarily) be an effect of not
having to share the per-CPU data-structures, as tuning per-CPU size
can achieve similar performance.
bulk - slab_nomerge - normal SLUB merge
1 - 49 cycles(tsc) - 49 cycles(tsc) - merge slower with cycles:0
2 - 30 cycles(tsc) - 30 cycles(tsc) - merge slower with cycles:0
3 - 23 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:0
4 - 20 cycles(tsc) - 20 cycles(tsc) - merge slower with cycles:0
8 - 18 cycles(tsc) - 18 cycles(tsc) - merge slower with cycles:0
16 - 17 cycles(tsc) - 17 cycles(tsc) - merge slower with cycles:0
30 - 18 cycles(tsc) - 23 cycles(tsc) - merge slower with cycles:5
32 - 18 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:4
34 - 23 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:-1
48 - 21 cycles(tsc) - 22 cycles(tsc) - merge slower with cycles:1
64 - 20 cycles(tsc) - 48 cycles(tsc) - merge slower with cycles:28
128 - 27 cycles(tsc) - 57 cycles(tsc) - merge slower with cycles:30
158 - 30 cycles(tsc) - 59 cycles(tsc) - merge slower with cycles:29
250 - 37 cycles(tsc) - 56 cycles(tsc) - merge slower with cycles:19
Joint work with Alexander Duyck.
[1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test01.c
[akpm@linux-foundation.org: BUG_ON -> WARN_ON;return]
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-20 15:57:49 -08:00
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2015-09-04 15:45:34 -07:00
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2015-09-04 15:45:37 -07:00
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2015-11-20 15:57:58 -08:00
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2015-09-04 15:45:34 -07:00
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2015-09-04 15:45:37 -07:00
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2015-11-20 15:57:52 -08:00
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2015-09-04 15:45:37 -07:00
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2015-09-04 15:45:40 -07:00
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2015-11-20 15:57:38 -08:00
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2015-09-04 15:45:40 -07:00
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2015-11-20 15:57:38 -08:00
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2015-09-04 15:45:40 -07:00
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2015-09-04 15:45:37 -07:00
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mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:59:19 -07:00
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2015-09-04 15:45:37 -07:00
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2015-11-20 15:57:52 -08:00
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2015-11-20 15:57:58 -08:00
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2015-11-20 15:57:38 -08:00
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2015-11-20 15:57:52 -08:00
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2015-11-20 15:57:58 -08:00
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2015-09-04 15:45:34 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2008-04-14 19:13:29 +03:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2018-06-07 17:09:10 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2018-06-07 17:09:10 -07:00
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2008-10-22 23:00:38 +04:00
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2008-04-14 19:11:30 +03:00
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2018-06-07 17:09:10 -07:00
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2007-05-09 02:32:46 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2018-06-07 17:09:10 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:46 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2018-06-07 17:09:10 -07:00
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2007-05-09 02:32:46 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-09 02:32:46 -07:00
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2015-11-05 18:45:46 -08:00
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2007-05-09 02:32:46 -07:00
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2008-04-14 19:11:41 +03:00
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2018-06-07 17:09:10 -07:00
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2009-02-12 18:00:17 +02:00
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2007-05-09 02:32:46 -07:00
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2018-04-05 16:21:39 -07:00
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2008-04-14 19:13:29 +03:00
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2007-05-09 02:32:46 -07:00
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2018-06-07 17:09:10 -07:00
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2007-05-09 02:32:46 -07:00
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2009-08-19 21:44:13 +03:00
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2007-05-09 02:32:46 -07:00
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2018-06-07 17:09:10 -07:00
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2007-05-09 02:32:46 -07:00
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2018-06-07 17:09:10 -07:00
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2009-04-23 09:58:22 +03:00
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2007-05-09 02:32:46 -07:00
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2008-08-05 09:28:47 +03:00
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2012-05-11 00:50:47 +09:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:32 -07:00
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2008-04-14 18:53:02 +03:00
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2008-09-11 12:25:41 -07:00
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2007-05-06 14:49:42 -07:00
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2007-07-17 04:03:32 -07:00
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2007-05-06 14:49:36 -07:00
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2010-08-20 12:37:13 -05:00
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2007-10-16 01:26:08 -07:00
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2010-08-20 12:37:14 -05:00
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2013-01-10 19:14:19 +00:00
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2009-12-18 16:26:20 -06:00
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2011-02-25 11:38:54 -06:00
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2011-06-02 10:19:41 -04:00
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2011-02-25 11:38:54 -06:00
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2011-06-02 10:19:41 -04:00
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2009-12-18 16:26:20 -06:00
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2011-02-25 11:38:54 -06:00
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2007-10-16 01:26:08 -07:00
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2010-08-20 12:37:15 -05:00
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2007-05-06 14:49:36 -07:00
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2013-11-08 20:47:37 +08:00
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2007-10-16 01:26:08 -07:00
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2007-05-06 14:49:36 -07:00
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2010-08-20 12:37:13 -05:00
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2007-05-06 14:49:36 -07:00
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2010-08-20 12:37:15 -05:00
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2007-05-06 14:49:36 -07:00
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2010-08-20 12:37:15 -05:00
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2007-05-06 14:49:36 -07:00
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2007-08-22 14:01:57 -07:00
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2014-06-04 16:06:34 -07:00
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2007-08-22 14:01:57 -07:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:32 -07:00
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2010-09-29 07:15:01 -05:00
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2010-08-20 12:37:15 -05:00
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2007-07-17 04:03:32 -07:00
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2018-12-28 00:29:41 -08:00
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2016-03-25 14:22:02 -07:00
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2018-12-28 00:29:41 -08:00
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2012-05-11 00:50:47 +09:00
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2010-08-20 12:37:15 -05:00
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2008-02-15 23:45:26 -08:00
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2014-01-24 07:20:23 -08:00
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2014-02-10 14:25:46 -08:00
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2014-01-24 07:20:23 -08:00
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2014-02-10 14:25:46 -08:00
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2007-05-06 14:49:36 -07:00
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2014-08-06 16:04:09 -07:00
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2007-05-06 14:49:36 -07:00
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2014-08-06 16:04:09 -07:00
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2007-05-06 14:49:36 -07:00
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2017-09-06 16:19:15 -07:00
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2007-05-06 14:49:36 -07:00
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2016-02-17 13:11:37 -08:00
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2016-07-26 15:21:59 -07:00
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2016-02-17 13:11:37 -08:00
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2010-08-20 12:37:13 -05:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:25:33 -07:00
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2007-05-06 14:49:36 -07:00
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2010-05-21 14:41:35 -07:00
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2010-08-20 12:37:13 -05:00
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2010-05-21 14:41:35 -07:00
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2007-05-06 14:49:36 -07:00
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2010-08-20 12:37:15 -05:00
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2010-08-20 12:37:13 -05:00
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2010-05-21 14:41:35 -07:00
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2012-05-11 00:50:47 +09:00
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2017-09-06 16:19:15 -07:00
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2007-05-06 14:49:36 -07:00
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2009-02-25 09:16:35 +02:00
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2009-02-22 17:40:07 -08:00
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2017-07-06 15:36:34 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:41 +03:00
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2007-05-06 14:49:36 -07:00
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2017-11-15 17:32:18 -08:00
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2018-04-05 16:21:28 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2008-02-15 23:45:25 -08:00
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2007-05-06 14:49:36 -07:00
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2017-01-18 02:53:44 -08:00
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2007-05-16 22:10:50 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2012-06-13 10:24:57 -05:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:44 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2017-01-18 02:53:44 -08:00
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2007-05-16 22:10:50 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-23 13:57:31 -07:00
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2007-05-06 14:49:36 -07:00
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2016-07-28 15:49:07 -07:00
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2007-05-06 14:49:36 -07:00
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2016-07-28 15:49:07 -07:00
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2016-03-15 14:55:12 -07:00
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2007-05-06 14:49:36 -07:00
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2008-12-29 22:14:56 +01:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:12 -07:00
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2007-05-09 02:32:44 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2012-11-28 16:23:16 +00:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:41 +03:00
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2018-06-07 17:09:10 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2008-02-14 14:21:32 -08:00
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2008-04-14 19:11:31 +03:00
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2008-02-14 14:21:32 -08:00
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2013-01-10 19:14:19 +00:00
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2008-02-14 14:21:32 -08:00
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mm: add support for kmem caches in DMA32 zone
Patch series "iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables",
v6.
This is a followup to the discussion in [1], [2].
IOMMUs using ARMv7 short-descriptor format require page tables (level 1
and 2) to be allocated within the first 4GB of RAM, even on 64-bit
systems.
For L1 tables that are bigger than a page, we can just use
__get_free_pages with GFP_DMA32 (on arm64 systems only, arm would still
use GFP_DMA).
For L2 tables that only take 1KB, it would be a waste to allocate a full
page, so we considered 3 approaches:
1. This series, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2 page
tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable to reuse
freed fragments until the whole page is freed. [3]
This series is the most memory-efficient approach.
stable@ note:
We confirmed that this is a regression, and IOMMU errors happen on 4.19
and linux-next/master on MT8173 (elm, Acer Chromebook R13). The issue
most likely starts from commit ad67f5a6545f ("arm64: replace ZONE_DMA
with ZONE_DMA32"), i.e. 4.15, and presumably breaks a number of Mediatek
platforms (and maybe others?).
[1] https://lists.linuxfoundation.org/pipermail/iommu/2018-November/030876.html
[2] https://lists.linuxfoundation.org/pipermail/iommu/2018-December/031696.html
[3] https://patchwork.codeaurora.org/patch/671639/
This patch (of 3):
IOMMUs using ARMv7 short-descriptor format require page tables to be
allocated within the first 4GB of RAM, even on 64-bit systems. On arm64,
this is done by passing GFP_DMA32 flag to memory allocation functions.
For IOMMU L2 tables that only take 1KB, it would be a waste to allocate
a full page using get_free_pages, so we considered 3 approaches:
1. This patch, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2
page tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable
to reuse freed fragments until the whole page is freed.
This change makes it possible to create a custom cache in DMA32 zone using
kmem_cache_create, then allocate memory using kmem_cache_alloc.
We do not create a DMA32 kmalloc cache array, as there are currently no
users of kmalloc(..., GFP_DMA32). These calls will continue to trigger a
warning, as we keep GFP_DMA32 in GFP_SLAB_BUG_MASK.
This implies that calls to kmem_cache_*alloc on a SLAB_CACHE_DMA32
kmem_cache must _not_ use GFP_DMA32 (it is anyway redundant and
unnecessary).
Link: http://lkml.kernel.org/r/20181210011504.122604-2-drinkcat@chromium.org
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Sasha Levin <Alexander.Levin@microsoft.com>
Cc: Huaisheng Ye <yehs1@lenovo.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Yong Wu <yong.wu@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Tomasz Figa <tfiga@google.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-28 20:43:42 -07:00
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2008-02-14 14:21:32 -08:00
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2007-05-06 14:49:36 -07:00
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2018-06-07 17:09:10 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:31 +03:00
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2007-05-06 14:49:36 -07:00
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2017-11-15 17:32:18 -08:00
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2007-05-06 14:49:36 -07:00
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2012-09-04 23:18:33 +00:00
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2017-09-06 16:19:18 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:41 +03:00
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2007-05-06 14:49:36 -07:00
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2009-07-27 18:30:35 -07:00
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2012-06-13 10:24:57 -05:00
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2009-07-27 18:30:35 -07:00
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2007-05-06 14:49:36 -07:00
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2012-01-12 17:17:33 -08:00
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2016-03-15 14:55:09 -07:00
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2011-06-01 12:25:49 -05:00
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2009-02-22 17:40:07 -08:00
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2011-08-09 16:12:27 -05:00
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2017-07-06 15:36:34 -07:00
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2011-08-09 16:12:27 -05:00
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2007-05-06 14:49:36 -07:00
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2008-08-19 08:51:22 -05:00
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2007-05-06 14:49:36 -07:00
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2016-07-26 15:21:59 -07:00
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2010-08-20 12:37:13 -05:00
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2007-10-16 01:26:05 -07:00
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2007-05-06 14:49:36 -07:00
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2010-08-20 12:37:13 -05:00
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2012-09-05 00:20:34 +00:00
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2009-12-18 16:26:22 -06:00
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2007-10-16 01:26:08 -07:00
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2007-05-06 14:49:36 -07:00
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2012-09-05 00:20:34 +00:00
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2007-05-06 14:49:36 -07:00
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2008-04-25 12:22:43 -07:00
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2018-10-26 15:03:06 -07:00
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2010-03-24 22:25:47 +01:00
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2012-09-04 23:18:33 +00:00
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2008-04-25 12:22:43 -07:00
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2011-04-15 14:48:13 -05:00
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2008-04-25 12:22:43 -07:00
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2014-06-04 16:06:34 -07:00
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2008-04-25 12:22:43 -07:00
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2018-10-26 15:03:06 -07:00
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2008-04-25 12:22:43 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-23 12:36:52 -07:00
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2016-02-17 13:11:37 -08:00
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2007-05-06 14:49:36 -07:00
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2008-04-23 12:36:52 -07:00
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2007-05-06 14:49:36 -07:00
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mm/slub.c: run free_partial() outside of the kmem_cache_node->list_lock
With debugobjects enabled and using SLAB_DESTROY_BY_RCU, when a
kmem_cache_node is destroyed the call_rcu() may trigger a slab
allocation to fill the debug object pool (__debug_object_init:fill_pool).
Everywhere but during kmem_cache_destroy(), discard_slab() is performed
outside of the kmem_cache_node->list_lock and avoids a lockdep warning
about potential recursion:
=============================================
[ INFO: possible recursive locking detected ]
4.8.0-rc1-gfxbench+ #1 Tainted: G U
---------------------------------------------
rmmod/8895 is trying to acquire lock:
(&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811c80d7>] get_partial_node.isra.63+0x47/0x430
but task is already holding lock:
(&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811cbda4>] __kmem_cache_shutdown+0x54/0x320
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(&n->list_lock)->rlock);
lock(&(&n->list_lock)->rlock);
*** DEADLOCK ***
May be due to missing lock nesting notation
5 locks held by rmmod/8895:
#0: (&dev->mutex){......}, at: driver_detach+0x42/0xc0
#1: (&dev->mutex){......}, at: driver_detach+0x50/0xc0
#2: (cpu_hotplug.dep_map){++++++}, at: get_online_cpus+0x2d/0x80
#3: (slab_mutex){+.+.+.}, at: kmem_cache_destroy+0x3c/0x220
#4: (&(&n->list_lock)->rlock){-.-...}, at: __kmem_cache_shutdown+0x54/0x320
stack backtrace:
CPU: 6 PID: 8895 Comm: rmmod Tainted: G U 4.8.0-rc1-gfxbench+ #1
Hardware name: Gigabyte Technology Co., Ltd. H87M-D3H/H87M-D3H, BIOS F11 08/18/2015
Call Trace:
__lock_acquire+0x1646/0x1ad0
lock_acquire+0xb2/0x200
_raw_spin_lock+0x36/0x50
get_partial_node.isra.63+0x47/0x430
___slab_alloc.constprop.67+0x1a7/0x3b0
__slab_alloc.isra.64.constprop.66+0x43/0x80
kmem_cache_alloc+0x236/0x2d0
__debug_object_init+0x2de/0x400
debug_object_activate+0x109/0x1e0
__call_rcu.constprop.63+0x32/0x2f0
call_rcu+0x12/0x20
discard_slab+0x3d/0x40
__kmem_cache_shutdown+0xdb/0x320
shutdown_cache+0x19/0x60
kmem_cache_destroy+0x1ae/0x220
i915_gem_load_cleanup+0x14/0x40 [i915]
i915_driver_unload+0x151/0x180 [i915]
i915_pci_remove+0x14/0x20 [i915]
pci_device_remove+0x34/0xb0
__device_release_driver+0x95/0x140
driver_detach+0xb6/0xc0
bus_remove_driver+0x53/0xd0
driver_unregister+0x27/0x50
pci_unregister_driver+0x25/0x70
i915_exit+0x1a/0x1e2 [i915]
SyS_delete_module+0x193/0x1f0
entry_SYSCALL_64_fastpath+0x1c/0xac
Fixes: 52b4b950b507 ("mm: slab: free kmem_cache_node after destroy sysfs file")
Link: http://lkml.kernel.org/r/1470759070-18743-1-git-send-email-chris@chris-wilson.co.uk
Reported-by: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-10 16:27:58 -07:00
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2007-05-06 14:49:36 -07:00
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2016-02-17 13:11:37 -08:00
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2019-05-13 17:16:12 -07:00
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2007-05-06 14:49:36 -07:00
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2016-02-17 13:11:37 -08:00
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2019-05-13 17:16:12 -07:00
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2008-04-25 12:22:43 -07:00
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2016-02-17 13:11:37 -08:00
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2008-04-23 12:36:52 -07:00
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2008-04-25 12:22:43 -07:00
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2016-02-17 13:11:37 -08:00
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mm/slub.c: run free_partial() outside of the kmem_cache_node->list_lock
With debugobjects enabled and using SLAB_DESTROY_BY_RCU, when a
kmem_cache_node is destroyed the call_rcu() may trigger a slab
allocation to fill the debug object pool (__debug_object_init:fill_pool).
Everywhere but during kmem_cache_destroy(), discard_slab() is performed
outside of the kmem_cache_node->list_lock and avoids a lockdep warning
about potential recursion:
=============================================
[ INFO: possible recursive locking detected ]
4.8.0-rc1-gfxbench+ #1 Tainted: G U
---------------------------------------------
rmmod/8895 is trying to acquire lock:
(&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811c80d7>] get_partial_node.isra.63+0x47/0x430
but task is already holding lock:
(&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811cbda4>] __kmem_cache_shutdown+0x54/0x320
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(&n->list_lock)->rlock);
lock(&(&n->list_lock)->rlock);
*** DEADLOCK ***
May be due to missing lock nesting notation
5 locks held by rmmod/8895:
#0: (&dev->mutex){......}, at: driver_detach+0x42/0xc0
#1: (&dev->mutex){......}, at: driver_detach+0x50/0xc0
#2: (cpu_hotplug.dep_map){++++++}, at: get_online_cpus+0x2d/0x80
#3: (slab_mutex){+.+.+.}, at: kmem_cache_destroy+0x3c/0x220
#4: (&(&n->list_lock)->rlock){-.-...}, at: __kmem_cache_shutdown+0x54/0x320
stack backtrace:
CPU: 6 PID: 8895 Comm: rmmod Tainted: G U 4.8.0-rc1-gfxbench+ #1
Hardware name: Gigabyte Technology Co., Ltd. H87M-D3H/H87M-D3H, BIOS F11 08/18/2015
Call Trace:
__lock_acquire+0x1646/0x1ad0
lock_acquire+0xb2/0x200
_raw_spin_lock+0x36/0x50
get_partial_node.isra.63+0x47/0x430
___slab_alloc.constprop.67+0x1a7/0x3b0
__slab_alloc.isra.64.constprop.66+0x43/0x80
kmem_cache_alloc+0x236/0x2d0
__debug_object_init+0x2de/0x400
debug_object_activate+0x109/0x1e0
__call_rcu.constprop.63+0x32/0x2f0
call_rcu+0x12/0x20
discard_slab+0x3d/0x40
__kmem_cache_shutdown+0xdb/0x320
shutdown_cache+0x19/0x60
kmem_cache_destroy+0x1ae/0x220
i915_gem_load_cleanup+0x14/0x40 [i915]
i915_driver_unload+0x151/0x180 [i915]
i915_pci_remove+0x14/0x20 [i915]
pci_device_remove+0x34/0xb0
__device_release_driver+0x95/0x140
driver_detach+0xb6/0xc0
bus_remove_driver+0x53/0xd0
driver_unregister+0x27/0x50
pci_unregister_driver+0x25/0x70
i915_exit+0x1a/0x1e2 [i915]
SyS_delete_module+0x193/0x1f0
entry_SYSCALL_64_fastpath+0x1c/0xac
Fixes: 52b4b950b507 ("mm: slab: free kmem_cache_node after destroy sysfs file")
Link: http://lkml.kernel.org/r/1470759070-18743-1-git-send-email-chris@chris-wilson.co.uk
Reported-by: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-10 16:27:58 -07:00
|
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2019-05-13 17:16:12 -07:00
|
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|
mm/slub.c: run free_partial() outside of the kmem_cache_node->list_lock
With debugobjects enabled and using SLAB_DESTROY_BY_RCU, when a
kmem_cache_node is destroyed the call_rcu() may trigger a slab
allocation to fill the debug object pool (__debug_object_init:fill_pool).
Everywhere but during kmem_cache_destroy(), discard_slab() is performed
outside of the kmem_cache_node->list_lock and avoids a lockdep warning
about potential recursion:
=============================================
[ INFO: possible recursive locking detected ]
4.8.0-rc1-gfxbench+ #1 Tainted: G U
---------------------------------------------
rmmod/8895 is trying to acquire lock:
(&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811c80d7>] get_partial_node.isra.63+0x47/0x430
but task is already holding lock:
(&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811cbda4>] __kmem_cache_shutdown+0x54/0x320
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(&n->list_lock)->rlock);
lock(&(&n->list_lock)->rlock);
*** DEADLOCK ***
May be due to missing lock nesting notation
5 locks held by rmmod/8895:
#0: (&dev->mutex){......}, at: driver_detach+0x42/0xc0
#1: (&dev->mutex){......}, at: driver_detach+0x50/0xc0
#2: (cpu_hotplug.dep_map){++++++}, at: get_online_cpus+0x2d/0x80
#3: (slab_mutex){+.+.+.}, at: kmem_cache_destroy+0x3c/0x220
#4: (&(&n->list_lock)->rlock){-.-...}, at: __kmem_cache_shutdown+0x54/0x320
stack backtrace:
CPU: 6 PID: 8895 Comm: rmmod Tainted: G U 4.8.0-rc1-gfxbench+ #1
Hardware name: Gigabyte Technology Co., Ltd. H87M-D3H/H87M-D3H, BIOS F11 08/18/2015
Call Trace:
__lock_acquire+0x1646/0x1ad0
lock_acquire+0xb2/0x200
_raw_spin_lock+0x36/0x50
get_partial_node.isra.63+0x47/0x430
___slab_alloc.constprop.67+0x1a7/0x3b0
__slab_alloc.isra.64.constprop.66+0x43/0x80
kmem_cache_alloc+0x236/0x2d0
__debug_object_init+0x2de/0x400
debug_object_activate+0x109/0x1e0
__call_rcu.constprop.63+0x32/0x2f0
call_rcu+0x12/0x20
discard_slab+0x3d/0x40
__kmem_cache_shutdown+0xdb/0x320
shutdown_cache+0x19/0x60
kmem_cache_destroy+0x1ae/0x220
i915_gem_load_cleanup+0x14/0x40 [i915]
i915_driver_unload+0x151/0x180 [i915]
i915_pci_remove+0x14/0x20 [i915]
pci_device_remove+0x34/0xb0
__device_release_driver+0x95/0x140
driver_detach+0xb6/0xc0
bus_remove_driver+0x53/0xd0
driver_unregister+0x27/0x50
pci_unregister_driver+0x25/0x70
i915_exit+0x1a/0x1e2 [i915]
SyS_delete_module+0x193/0x1f0
entry_SYSCALL_64_fastpath+0x1c/0xac
Fixes: 52b4b950b507 ("mm: slab: free kmem_cache_node after destroy sysfs file")
Link: http://lkml.kernel.org/r/1470759070-18743-1-git-send-email-chris@chris-wilson.co.uk
Reported-by: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-10 16:27:58 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:57 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2016-02-17 13:11:37 -08:00
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2007-05-06 14:49:36 -07:00
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2014-08-06 16:04:09 -07:00
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2007-05-06 14:49:36 -07:00
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2014-08-06 16:04:09 -07:00
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2008-04-23 12:36:52 -07:00
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2007-05-06 14:49:36 -07:00
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2017-02-22 15:41:11 -08:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:24:38 -07:00
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2008-08-19 20:43:26 +03:00
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2007-05-06 14:49:36 -07:00
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2013-01-10 19:14:19 +00:00
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2008-02-11 22:47:46 +02:00
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2007-10-16 01:24:38 -07:00
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2013-01-10 19:14:19 +00:00
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2007-10-16 01:24:38 -07:00
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2007-07-17 04:03:22 -07:00
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2012-09-08 17:47:58 -03:00
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2008-08-19 20:43:26 +03:00
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2009-03-23 15:12:24 +02:00
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2008-08-19 20:43:26 +03:00
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kasan, mm: change hooks signatures
Patch series "kasan: add software tag-based mode for arm64", v13.
This patchset adds a new software tag-based mode to KASAN [1]. (Initially
this mode was called KHWASAN, but it got renamed, see the naming rationale
at the end of this section).
The plan is to implement HWASan [2] for the kernel with the incentive,
that it's going to have comparable to KASAN performance, but in the same
time consume much less memory, trading that off for somewhat imprecise bug
detection and being supported only for arm64.
The underlying ideas of the approach used by software tag-based KASAN are:
1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store
pointer tags in the top byte of each kernel pointer.
2. Using shadow memory, we can store memory tags for each chunk of kernel
memory.
3. On each memory allocation, we can generate a random tag, embed it into
the returned pointer and set the memory tags that correspond to this
chunk of memory to the same value.
4. By using compiler instrumentation, before each memory access we can add
a check that the pointer tag matches the tag of the memory that is being
accessed.
5. On a tag mismatch we report an error.
With this patchset the existing KASAN mode gets renamed to generic KASAN,
with the word "generic" meaning that the implementation can be supported
by any architecture as it is purely software.
The new mode this patchset adds is called software tag-based KASAN. The
word "tag-based" refers to the fact that this mode uses tags embedded into
the top byte of kernel pointers and the TBI arm64 CPU feature that allows
to dereference such pointers. The word "software" here means that shadow
memory manipulation and tag checking on pointer dereference is done in
software. As it is the only tag-based implementation right now, "software
tag-based" KASAN is sometimes referred to as simply "tag-based" in this
patchset.
A potential expansion of this mode is a hardware tag-based mode, which
would use hardware memory tagging support (announced by Arm [3]) instead
of compiler instrumentation and manual shadow memory manipulation.
Same as generic KASAN, software tag-based KASAN is strictly a debugging
feature.
[1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html
[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a
====== Rationale
On mobile devices generic KASAN's memory usage is significant problem.
One of the main reasons to have tag-based KASAN is to be able to perform a
similar set of checks as the generic one does, but with lower memory
requirements.
Comment from Vishwath Mohan <vishwath@google.com>:
I don't have data on-hand, but anecdotally both ASAN and KASAN have proven
problematic to enable for environments that don't tolerate the increased
memory pressure well. This includes
(a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go,
(c) Connected components like Pixel's visual core [1].
These are both places I'd love to have a low(er) memory footprint option at
my disposal.
Comment from Evgenii Stepanov <eugenis@google.com>:
Looking at a live Android device under load, slab (according to
/proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's
overhead of 2x - 3x on top of it is not insignificant.
Not having this overhead enables near-production use - ex. running
KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do
not reproduce in test configuration. These are the ones that often cost
the most engineering time to track down.
CPU overhead is bad, but generally tolerable. RAM is critical, in our
experience. Once it gets low enough, OOM-killer makes your life
miserable.
[1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/
====== Technical details
Software tag-based KASAN mode is implemented in a very similar way to the
generic one. This patchset essentially does the following:
1. TCR_TBI1 is set to enable Top Byte Ignore.
2. Shadow memory is used (with a different scale, 1:16, so each shadow
byte corresponds to 16 bytes of kernel memory) to store memory tags.
3. All slab objects are aligned to shadow scale, which is 16 bytes.
4. All pointers returned from the slab allocator are tagged with a random
tag and the corresponding shadow memory is poisoned with the same value.
5. Compiler instrumentation is used to insert tag checks. Either by
calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and
CONFIG_KASAN_INLINE flags are reused).
6. When a tag mismatch is detected in callback instrumentation mode
KASAN simply prints a bug report. In case of inline instrumentation,
clang inserts a brk instruction, and KASAN has it's own brk handler,
which reports the bug.
7. The memory in between slab objects is marked with a reserved tag, and
acts as a redzone.
8. When a slab object is freed it's marked with a reserved tag.
Bug detection is imprecise for two reasons:
1. We won't catch some small out-of-bounds accesses, that fall into the
same shadow cell, as the last byte of a slab object.
2. We only have 1 byte to store tags, which means we have a 1/256
probability of a tag match for an incorrect access (actually even
slightly less due to reserved tag values).
Despite that there's a particular type of bugs that tag-based KASAN can
detect compared to generic KASAN: use-after-free after the object has been
allocated by someone else.
====== Testing
Some kernel developers voiced a concern that changing the top byte of
kernel pointers may lead to subtle bugs that are difficult to discover.
To address this concern deliberate testing has been performed.
It doesn't seem feasible to do some kind of static checking to find
potential issues with pointer tagging, so a dynamic approach was taken.
All pointer comparisons/subtractions have been instrumented in an LLVM
compiler pass and a kernel module that would print a bug report whenever
two pointers with different tags are being compared/subtracted (ignoring
comparisons with NULL pointers and with pointers obtained by casting an
error code to a pointer type) has been used. Then the kernel has been
booted in QEMU and on an Odroid C2 board and syzkaller has been run.
This yielded the following results.
The two places that look interesting are:
is_vmalloc_addr in include/linux/mm.h
is_kernel_rodata in mm/util.c
Here we compare a pointer with some fixed untagged values to make sure
that the pointer lies in a particular part of the kernel address space.
Since tag-based KASAN doesn't add tags to pointers that belong to rodata
or vmalloc regions, this should work as is. To make sure debug checks to
those two functions that check that the result doesn't change whether we
operate on pointers with or without untagging has been added.
A few other cases that don't look that interesting:
Comparing pointers to achieve unique sorting order of pointee objects
(e.g. sorting locks addresses before performing a double lock):
tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c
pipe_double_lock in fs/pipe.c
unix_state_double_lock in net/unix/af_unix.c
lock_two_nondirectories in fs/inode.c
mutex_lock_double in kernel/events/core.c
ep_cmp_ffd in fs/eventpoll.c
fsnotify_compare_groups fs/notify/mark.c
Nothing needs to be done here, since the tags embedded into pointers
don't change, so the sorting order would still be unique.
Checks that a pointer belongs to some particular allocation:
is_sibling_entry in lib/radix-tree.c
object_is_on_stack in include/linux/sched/task_stack.h
Nothing needs to be done here either, since two pointers can only belong
to the same allocation if they have the same tag.
Overall, since the kernel boots and works, there are no critical bugs.
As for the rest, the traditional kernel testing way (use until fails) is
the only one that looks feasible.
Another point here is that tag-based KASAN is available under a separate
config option that needs to be deliberately enabled. Even though it might
be used in a "near-production" environment to find bugs that are not found
during fuzzing or running tests, it is still a debug tool.
====== Benchmarks
The following numbers were collected on Odroid C2 board. Both generic and
tag-based KASAN were used in inline instrumentation mode.
Boot time [1]:
* ~1.7 sec for clean kernel
* ~5.0 sec for generic KASAN
* ~5.0 sec for tag-based KASAN
Network performance [2]:
* 8.33 Gbits/sec for clean kernel
* 3.17 Gbits/sec for generic KASAN
* 2.85 Gbits/sec for tag-based KASAN
Slab memory usage after boot [3]:
* ~40 kb for clean kernel
* ~105 kb (~260% overhead) for generic KASAN
* ~47 kb (~20% overhead) for tag-based KASAN
KASAN memory overhead consists of three main parts:
1. Increased slab memory usage due to redzones.
2. Shadow memory (the whole reserved once during boot).
3. Quaratine (grows gradually until some preset limit; the more the limit,
the more the chance to detect a use-after-free).
Comparing tag-based vs generic KASAN for each of these points:
1. 20% vs 260% overhead.
2. 1/16th vs 1/8th of physical memory.
3. Tag-based KASAN doesn't require quarantine.
[1] Time before the ext4 driver is initialized.
[2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
[3] Measured as `cat /proc/meminfo | grep Slab`.
====== Some notes
A few notes:
1. The patchset can be found here:
https://github.com/xairy/kasan-prototype/tree/khwasan
2. Building requires a recent Clang version (7.0.0 or later).
3. Stack instrumentation is not supported yet and will be added later.
This patch (of 25):
Tag-based KASAN changes the value of the top byte of pointers returned
from the kernel allocation functions (such as kmalloc). This patch
updates KASAN hooks signatures and their usage in SLAB and SLUB code to
reflect that.
Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 00:29:37 -08:00
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2015-02-13 14:39:42 -08:00
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2008-08-19 20:43:26 +03:00
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2007-05-06 14:49:36 -07:00
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2010-09-29 21:02:15 +09:00
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2008-03-01 13:56:40 -08:00
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2008-11-25 16:55:53 +01:00
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2009-07-07 10:32:59 +01:00
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2008-03-01 13:56:40 -08:00
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2017-11-15 17:35:54 -08:00
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mm: charge/uncharge kmemcg from generic page allocator paths
Currently, to charge a non-slab allocation to kmemcg one has to use
alloc_kmem_pages helper with __GFP_ACCOUNT flag. A page allocated with
this helper should finally be freed using free_kmem_pages, otherwise it
won't be uncharged.
This API suits its current users fine, but it turns out to be impossible
to use along with page reference counting, i.e. when an allocation is
supposed to be freed with put_page, as it is the case with pipe or unix
socket buffers.
To overcome this limitation, this patch moves charging/uncharging to
generic page allocator paths, i.e. to __alloc_pages_nodemask and
free_pages_prepare, and zaps alloc/free_kmem_pages helpers. This way,
one can use any of the available page allocation functions to get the
allocated page charged to kmemcg - it's enough to pass __GFP_ACCOUNT,
just like in case of kmalloc and friends. A charged page will be
automatically uncharged on free.
To make it possible, we need to mark pages charged to kmemcg somehow.
To avoid introducing a new page flag, we make use of page->_mapcount for
marking such pages. Since pages charged to kmemcg are not supposed to
be mapped to userspace, it should work just fine. There are other
(ab)users of page->_mapcount - buddy and balloon pages - but we don't
conflict with them.
In case kmemcg is compiled out or not used at runtime, this patch
introduces no overhead to generic page allocator paths. If kmemcg is
used, it will be plus one gfp flags check on alloc and plus one
page->_mapcount check on free, which shouldn't hurt performance, because
the data accessed are hot.
Link: http://lkml.kernel.org/r/a9736d856f895bcb465d9f257b54efe32eda6f99.1464079538.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 15:24:24 -07:00
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2008-03-01 13:56:40 -08:00
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2009-07-07 10:32:59 +01:00
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kasan, mm: change hooks signatures
Patch series "kasan: add software tag-based mode for arm64", v13.
This patchset adds a new software tag-based mode to KASAN [1]. (Initially
this mode was called KHWASAN, but it got renamed, see the naming rationale
at the end of this section).
The plan is to implement HWASan [2] for the kernel with the incentive,
that it's going to have comparable to KASAN performance, but in the same
time consume much less memory, trading that off for somewhat imprecise bug
detection and being supported only for arm64.
The underlying ideas of the approach used by software tag-based KASAN are:
1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store
pointer tags in the top byte of each kernel pointer.
2. Using shadow memory, we can store memory tags for each chunk of kernel
memory.
3. On each memory allocation, we can generate a random tag, embed it into
the returned pointer and set the memory tags that correspond to this
chunk of memory to the same value.
4. By using compiler instrumentation, before each memory access we can add
a check that the pointer tag matches the tag of the memory that is being
accessed.
5. On a tag mismatch we report an error.
With this patchset the existing KASAN mode gets renamed to generic KASAN,
with the word "generic" meaning that the implementation can be supported
by any architecture as it is purely software.
The new mode this patchset adds is called software tag-based KASAN. The
word "tag-based" refers to the fact that this mode uses tags embedded into
the top byte of kernel pointers and the TBI arm64 CPU feature that allows
to dereference such pointers. The word "software" here means that shadow
memory manipulation and tag checking on pointer dereference is done in
software. As it is the only tag-based implementation right now, "software
tag-based" KASAN is sometimes referred to as simply "tag-based" in this
patchset.
A potential expansion of this mode is a hardware tag-based mode, which
would use hardware memory tagging support (announced by Arm [3]) instead
of compiler instrumentation and manual shadow memory manipulation.
Same as generic KASAN, software tag-based KASAN is strictly a debugging
feature.
[1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html
[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a
====== Rationale
On mobile devices generic KASAN's memory usage is significant problem.
One of the main reasons to have tag-based KASAN is to be able to perform a
similar set of checks as the generic one does, but with lower memory
requirements.
Comment from Vishwath Mohan <vishwath@google.com>:
I don't have data on-hand, but anecdotally both ASAN and KASAN have proven
problematic to enable for environments that don't tolerate the increased
memory pressure well. This includes
(a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go,
(c) Connected components like Pixel's visual core [1].
These are both places I'd love to have a low(er) memory footprint option at
my disposal.
Comment from Evgenii Stepanov <eugenis@google.com>:
Looking at a live Android device under load, slab (according to
/proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's
overhead of 2x - 3x on top of it is not insignificant.
Not having this overhead enables near-production use - ex. running
KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do
not reproduce in test configuration. These are the ones that often cost
the most engineering time to track down.
CPU overhead is bad, but generally tolerable. RAM is critical, in our
experience. Once it gets low enough, OOM-killer makes your life
miserable.
[1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/
====== Technical details
Software tag-based KASAN mode is implemented in a very similar way to the
generic one. This patchset essentially does the following:
1. TCR_TBI1 is set to enable Top Byte Ignore.
2. Shadow memory is used (with a different scale, 1:16, so each shadow
byte corresponds to 16 bytes of kernel memory) to store memory tags.
3. All slab objects are aligned to shadow scale, which is 16 bytes.
4. All pointers returned from the slab allocator are tagged with a random
tag and the corresponding shadow memory is poisoned with the same value.
5. Compiler instrumentation is used to insert tag checks. Either by
calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and
CONFIG_KASAN_INLINE flags are reused).
6. When a tag mismatch is detected in callback instrumentation mode
KASAN simply prints a bug report. In case of inline instrumentation,
clang inserts a brk instruction, and KASAN has it's own brk handler,
which reports the bug.
7. The memory in between slab objects is marked with a reserved tag, and
acts as a redzone.
8. When a slab object is freed it's marked with a reserved tag.
Bug detection is imprecise for two reasons:
1. We won't catch some small out-of-bounds accesses, that fall into the
same shadow cell, as the last byte of a slab object.
2. We only have 1 byte to store tags, which means we have a 1/256
probability of a tag match for an incorrect access (actually even
slightly less due to reserved tag values).
Despite that there's a particular type of bugs that tag-based KASAN can
detect compared to generic KASAN: use-after-free after the object has been
allocated by someone else.
====== Testing
Some kernel developers voiced a concern that changing the top byte of
kernel pointers may lead to subtle bugs that are difficult to discover.
To address this concern deliberate testing has been performed.
It doesn't seem feasible to do some kind of static checking to find
potential issues with pointer tagging, so a dynamic approach was taken.
All pointer comparisons/subtractions have been instrumented in an LLVM
compiler pass and a kernel module that would print a bug report whenever
two pointers with different tags are being compared/subtracted (ignoring
comparisons with NULL pointers and with pointers obtained by casting an
error code to a pointer type) has been used. Then the kernel has been
booted in QEMU and on an Odroid C2 board and syzkaller has been run.
This yielded the following results.
The two places that look interesting are:
is_vmalloc_addr in include/linux/mm.h
is_kernel_rodata in mm/util.c
Here we compare a pointer with some fixed untagged values to make sure
that the pointer lies in a particular part of the kernel address space.
Since tag-based KASAN doesn't add tags to pointers that belong to rodata
or vmalloc regions, this should work as is. To make sure debug checks to
those two functions that check that the result doesn't change whether we
operate on pointers with or without untagging has been added.
A few other cases that don't look that interesting:
Comparing pointers to achieve unique sorting order of pointee objects
(e.g. sorting locks addresses before performing a double lock):
tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c
pipe_double_lock in fs/pipe.c
unix_state_double_lock in net/unix/af_unix.c
lock_two_nondirectories in fs/inode.c
mutex_lock_double in kernel/events/core.c
ep_cmp_ffd in fs/eventpoll.c
fsnotify_compare_groups fs/notify/mark.c
Nothing needs to be done here, since the tags embedded into pointers
don't change, so the sorting order would still be unique.
Checks that a pointer belongs to some particular allocation:
is_sibling_entry in lib/radix-tree.c
object_is_on_stack in include/linux/sched/task_stack.h
Nothing needs to be done here either, since two pointers can only belong
to the same allocation if they have the same tag.
Overall, since the kernel boots and works, there are no critical bugs.
As for the rest, the traditional kernel testing way (use until fails) is
the only one that looks feasible.
Another point here is that tag-based KASAN is available under a separate
config option that needs to be deliberately enabled. Even though it might
be used in a "near-production" environment to find bugs that are not found
during fuzzing or running tests, it is still a debug tool.
====== Benchmarks
The following numbers were collected on Odroid C2 board. Both generic and
tag-based KASAN were used in inline instrumentation mode.
Boot time [1]:
* ~1.7 sec for clean kernel
* ~5.0 sec for generic KASAN
* ~5.0 sec for tag-based KASAN
Network performance [2]:
* 8.33 Gbits/sec for clean kernel
* 3.17 Gbits/sec for generic KASAN
* 2.85 Gbits/sec for tag-based KASAN
Slab memory usage after boot [3]:
* ~40 kb for clean kernel
* ~105 kb (~260% overhead) for generic KASAN
* ~47 kb (~20% overhead) for tag-based KASAN
KASAN memory overhead consists of three main parts:
1. Increased slab memory usage due to redzones.
2. Shadow memory (the whole reserved once during boot).
3. Quaratine (grows gradually until some preset limit; the more the limit,
the more the chance to detect a use-after-free).
Comparing tag-based vs generic KASAN for each of these points:
1. 20% vs 260% overhead.
2. 1/16th vs 1/8th of physical memory.
3. Tag-based KASAN doesn't require quarantine.
[1] Time before the ext4 driver is initialized.
[2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
[3] Measured as `cat /proc/meminfo | grep Slab`.
====== Some notes
A few notes:
1. The patchset can be found here:
https://github.com/xairy/kasan-prototype/tree/khwasan
2. Building requires a recent Clang version (7.0.0 or later).
3. Stack instrumentation is not supported yet and will be added later.
This patch (of 25):
Tag-based KASAN changes the value of the top byte of pointers returned
from the kernel allocation functions (such as kmalloc). This patch
updates KASAN hooks signatures and their usage in SLAB and SLUB code to
reflect that.
Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 00:29:37 -08:00
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2008-03-01 13:56:40 -08:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:24:38 -07:00
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2008-08-19 20:43:26 +03:00
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2007-05-06 14:49:36 -07:00
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2013-01-10 19:14:19 +00:00
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2008-08-19 20:43:26 +03:00
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2009-03-23 15:12:24 +02:00
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2008-08-19 20:43:26 +03:00
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2007-10-16 01:24:38 -07:00
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2013-01-10 19:14:19 +00:00
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2007-10-16 01:24:38 -07:00
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2007-07-17 04:03:22 -07:00
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2012-09-08 17:47:58 -03:00
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2008-08-19 20:43:26 +03:00
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2009-03-23 15:12:24 +02:00
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2008-08-19 20:43:26 +03:00
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kasan, mm: change hooks signatures
Patch series "kasan: add software tag-based mode for arm64", v13.
This patchset adds a new software tag-based mode to KASAN [1]. (Initially
this mode was called KHWASAN, but it got renamed, see the naming rationale
at the end of this section).
The plan is to implement HWASan [2] for the kernel with the incentive,
that it's going to have comparable to KASAN performance, but in the same
time consume much less memory, trading that off for somewhat imprecise bug
detection and being supported only for arm64.
The underlying ideas of the approach used by software tag-based KASAN are:
1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store
pointer tags in the top byte of each kernel pointer.
2. Using shadow memory, we can store memory tags for each chunk of kernel
memory.
3. On each memory allocation, we can generate a random tag, embed it into
the returned pointer and set the memory tags that correspond to this
chunk of memory to the same value.
4. By using compiler instrumentation, before each memory access we can add
a check that the pointer tag matches the tag of the memory that is being
accessed.
5. On a tag mismatch we report an error.
With this patchset the existing KASAN mode gets renamed to generic KASAN,
with the word "generic" meaning that the implementation can be supported
by any architecture as it is purely software.
The new mode this patchset adds is called software tag-based KASAN. The
word "tag-based" refers to the fact that this mode uses tags embedded into
the top byte of kernel pointers and the TBI arm64 CPU feature that allows
to dereference such pointers. The word "software" here means that shadow
memory manipulation and tag checking on pointer dereference is done in
software. As it is the only tag-based implementation right now, "software
tag-based" KASAN is sometimes referred to as simply "tag-based" in this
patchset.
A potential expansion of this mode is a hardware tag-based mode, which
would use hardware memory tagging support (announced by Arm [3]) instead
of compiler instrumentation and manual shadow memory manipulation.
Same as generic KASAN, software tag-based KASAN is strictly a debugging
feature.
[1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html
[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a
====== Rationale
On mobile devices generic KASAN's memory usage is significant problem.
One of the main reasons to have tag-based KASAN is to be able to perform a
similar set of checks as the generic one does, but with lower memory
requirements.
Comment from Vishwath Mohan <vishwath@google.com>:
I don't have data on-hand, but anecdotally both ASAN and KASAN have proven
problematic to enable for environments that don't tolerate the increased
memory pressure well. This includes
(a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go,
(c) Connected components like Pixel's visual core [1].
These are both places I'd love to have a low(er) memory footprint option at
my disposal.
Comment from Evgenii Stepanov <eugenis@google.com>:
Looking at a live Android device under load, slab (according to
/proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's
overhead of 2x - 3x on top of it is not insignificant.
Not having this overhead enables near-production use - ex. running
KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do
not reproduce in test configuration. These are the ones that often cost
the most engineering time to track down.
CPU overhead is bad, but generally tolerable. RAM is critical, in our
experience. Once it gets low enough, OOM-killer makes your life
miserable.
[1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/
====== Technical details
Software tag-based KASAN mode is implemented in a very similar way to the
generic one. This patchset essentially does the following:
1. TCR_TBI1 is set to enable Top Byte Ignore.
2. Shadow memory is used (with a different scale, 1:16, so each shadow
byte corresponds to 16 bytes of kernel memory) to store memory tags.
3. All slab objects are aligned to shadow scale, which is 16 bytes.
4. All pointers returned from the slab allocator are tagged with a random
tag and the corresponding shadow memory is poisoned with the same value.
5. Compiler instrumentation is used to insert tag checks. Either by
calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and
CONFIG_KASAN_INLINE flags are reused).
6. When a tag mismatch is detected in callback instrumentation mode
KASAN simply prints a bug report. In case of inline instrumentation,
clang inserts a brk instruction, and KASAN has it's own brk handler,
which reports the bug.
7. The memory in between slab objects is marked with a reserved tag, and
acts as a redzone.
8. When a slab object is freed it's marked with a reserved tag.
Bug detection is imprecise for two reasons:
1. We won't catch some small out-of-bounds accesses, that fall into the
same shadow cell, as the last byte of a slab object.
2. We only have 1 byte to store tags, which means we have a 1/256
probability of a tag match for an incorrect access (actually even
slightly less due to reserved tag values).
Despite that there's a particular type of bugs that tag-based KASAN can
detect compared to generic KASAN: use-after-free after the object has been
allocated by someone else.
====== Testing
Some kernel developers voiced a concern that changing the top byte of
kernel pointers may lead to subtle bugs that are difficult to discover.
To address this concern deliberate testing has been performed.
It doesn't seem feasible to do some kind of static checking to find
potential issues with pointer tagging, so a dynamic approach was taken.
All pointer comparisons/subtractions have been instrumented in an LLVM
compiler pass and a kernel module that would print a bug report whenever
two pointers with different tags are being compared/subtracted (ignoring
comparisons with NULL pointers and with pointers obtained by casting an
error code to a pointer type) has been used. Then the kernel has been
booted in QEMU and on an Odroid C2 board and syzkaller has been run.
This yielded the following results.
The two places that look interesting are:
is_vmalloc_addr in include/linux/mm.h
is_kernel_rodata in mm/util.c
Here we compare a pointer with some fixed untagged values to make sure
that the pointer lies in a particular part of the kernel address space.
Since tag-based KASAN doesn't add tags to pointers that belong to rodata
or vmalloc regions, this should work as is. To make sure debug checks to
those two functions that check that the result doesn't change whether we
operate on pointers with or without untagging has been added.
A few other cases that don't look that interesting:
Comparing pointers to achieve unique sorting order of pointee objects
(e.g. sorting locks addresses before performing a double lock):
tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c
pipe_double_lock in fs/pipe.c
unix_state_double_lock in net/unix/af_unix.c
lock_two_nondirectories in fs/inode.c
mutex_lock_double in kernel/events/core.c
ep_cmp_ffd in fs/eventpoll.c
fsnotify_compare_groups fs/notify/mark.c
Nothing needs to be done here, since the tags embedded into pointers
don't change, so the sorting order would still be unique.
Checks that a pointer belongs to some particular allocation:
is_sibling_entry in lib/radix-tree.c
object_is_on_stack in include/linux/sched/task_stack.h
Nothing needs to be done here either, since two pointers can only belong
to the same allocation if they have the same tag.
Overall, since the kernel boots and works, there are no critical bugs.
As for the rest, the traditional kernel testing way (use until fails) is
the only one that looks feasible.
Another point here is that tag-based KASAN is available under a separate
config option that needs to be deliberately enabled. Even though it might
be used in a "near-production" environment to find bugs that are not found
during fuzzing or running tests, it is still a debug tool.
====== Benchmarks
The following numbers were collected on Odroid C2 board. Both generic and
tag-based KASAN were used in inline instrumentation mode.
Boot time [1]:
* ~1.7 sec for clean kernel
* ~5.0 sec for generic KASAN
* ~5.0 sec for tag-based KASAN
Network performance [2]:
* 8.33 Gbits/sec for clean kernel
* 3.17 Gbits/sec for generic KASAN
* 2.85 Gbits/sec for tag-based KASAN
Slab memory usage after boot [3]:
* ~40 kb for clean kernel
* ~105 kb (~260% overhead) for generic KASAN
* ~47 kb (~20% overhead) for tag-based KASAN
KASAN memory overhead consists of three main parts:
1. Increased slab memory usage due to redzones.
2. Shadow memory (the whole reserved once during boot).
3. Quaratine (grows gradually until some preset limit; the more the limit,
the more the chance to detect a use-after-free).
Comparing tag-based vs generic KASAN for each of these points:
1. 20% vs 260% overhead.
2. 1/16th vs 1/8th of physical memory.
3. Tag-based KASAN doesn't require quarantine.
[1] Time before the ext4 driver is initialized.
[2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
[3] Measured as `cat /proc/meminfo | grep Slab`.
====== Some notes
A few notes:
1. The patchset can be found here:
https://github.com/xairy/kasan-prototype/tree/khwasan
2. Building requires a recent Clang version (7.0.0 or later).
3. Stack instrumentation is not supported yet and will be added later.
This patch (of 25):
Tag-based KASAN changes the value of the top byte of pointers returned
from the kernel allocation functions (such as kmalloc). This patch
updates KASAN hooks signatures and their usage in SLAB and SLUB code to
reflect that.
Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 00:29:37 -08:00
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2015-02-13 14:39:42 -08:00
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2008-08-19 20:43:26 +03:00
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2007-05-06 14:49:36 -07:00
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2019-05-13 17:16:09 -07:00
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2007-05-06 14:49:36 -07:00
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2016-06-23 15:24:05 -07:00
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2018-01-10 15:17:01 -08:00
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2016-06-23 15:24:05 -07:00
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2018-01-10 14:48:22 -08:00
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2016-06-23 15:24:05 -07:00
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2018-04-05 16:21:20 -07:00
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2016-06-23 15:24:05 -07:00
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2019-01-08 15:23:15 -08:00
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2016-06-23 15:24:05 -07:00
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2018-01-10 14:48:22 -08:00
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2016-06-23 15:24:05 -07:00
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2018-01-10 14:48:22 -08:00
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2016-06-23 15:24:05 -07:00
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2018-01-10 15:17:01 -08:00
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2018-01-10 14:48:22 -08:00
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2016-06-23 15:24:05 -07:00
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2018-01-10 15:17:01 -08:00
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2017-11-30 13:04:32 -08:00
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2018-01-10 15:17:01 -08:00
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2018-01-10 14:48:22 -08:00
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2016-06-23 15:24:05 -07:00
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2019-07-11 20:54:14 -07:00
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2007-05-06 14:49:36 -07:00
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2007-06-08 13:46:49 -07:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:24:46 -07:00
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2007-06-08 13:46:49 -07:00
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2007-12-04 23:45:30 -08:00
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2008-05-22 19:22:25 +03:00
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2007-12-04 23:45:30 -08:00
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2008-05-22 19:22:25 +03:00
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2007-05-06 14:49:36 -07:00
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slub: Commonize slab_cache field in struct page
Right now, slab and slub have fields in struct page to derive which
cache a page belongs to, but they do it slightly differently.
slab uses a field called slab_cache, that lives in the third double
word. slub, uses a field called "slab", living outside of the
doublewords area.
Ideally, we could use the same field for this. Since slub heavily makes
use of the doubleword region, there isn't really much room to move
slub's slab_cache field around. Since slab does not have such strict
placement restrictions, we can move it outside the doubleword area.
The naming used by slab, "slab_cache", is less confusing, and it is
preferred over slub's generic "slab".
Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2012-10-22 18:05:36 +04:00
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2007-05-06 14:49:36 -07:00
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2019-07-11 20:54:14 -07:00
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2007-05-06 14:49:36 -07:00
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2008-02-07 17:47:41 -08:00
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2007-05-06 14:49:36 -07:00
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2009-03-25 11:05:57 +02:00
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2007-10-16 01:24:44 -07:00
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2007-05-06 14:49:36 -07:00
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2007-05-06 14:49:41 -07:00
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2007-10-16 01:24:38 -07:00
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2008-05-28 10:32:22 -07:00
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2018-02-06 15:36:23 -08:00
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mm: charge/uncharge kmemcg from generic page allocator paths
Currently, to charge a non-slab allocation to kmemcg one has to use
alloc_kmem_pages helper with __GFP_ACCOUNT flag. A page allocated with
this helper should finally be freed using free_kmem_pages, otherwise it
won't be uncharged.
This API suits its current users fine, but it turns out to be impossible
to use along with page reference counting, i.e. when an allocation is
supposed to be freed with put_page, as it is the case with pipe or unix
socket buffers.
To overcome this limitation, this patch moves charging/uncharging to
generic page allocator paths, i.e. to __alloc_pages_nodemask and
free_pages_prepare, and zaps alloc/free_kmem_pages helpers. This way,
one can use any of the available page allocation functions to get the
allocated page charged to kmemcg - it's enough to pass __GFP_ACCOUNT,
just like in case of kmalloc and friends. A charged page will be
automatically uncharged on free.
To make it possible, we need to mark pages charged to kmemcg somehow.
To avoid introducing a new page flag, we make use of page->_mapcount for
marking such pages. Since pages charged to kmemcg are not supposed to
be mapped to userspace, it should work just fine. There are other
(ab)users of page->_mapcount - buddy and balloon pages - but we don't
conflict with them.
In case kmemcg is compiled out or not used at runtime, this patch
introduces no overhead to generic page allocator paths. If kmemcg is
used, it will be plus one gfp flags check on alloc and plus one
page->_mapcount check on free, which shouldn't hurt performance, because
the data accessed are hot.
Link: http://lkml.kernel.org/r/a9736d856f895bcb465d9f257b54efe32eda6f99.1464079538.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 15:24:24 -07:00
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2007-10-16 01:24:38 -07:00
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2015-11-20 15:57:46 -08:00
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2007-05-06 14:49:36 -07:00
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2015-02-12 14:59:41 -08:00
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2007-05-06 14:49:46 -07:00
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2015-02-12 14:59:41 -08:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:46 -07:00
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2017-02-22 15:41:27 -08:00
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2007-05-06 14:49:46 -07:00
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2015-02-12 14:59:41 -08:00
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2007-05-06 14:49:46 -07:00
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2015-02-12 14:59:44 -08:00
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2007-05-06 14:49:46 -07:00
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2014-08-06 16:04:09 -07:00
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2015-02-12 14:59:41 -08:00
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2007-05-06 14:49:46 -07:00
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2015-02-12 14:59:41 -08:00
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2007-05-06 14:49:46 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:46 -07:00
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2019-05-13 17:16:12 -07:00
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2015-02-12 14:59:41 -08:00
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2019-05-13 17:16:12 -07:00
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2011-08-09 16:12:22 -05:00
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2015-02-12 14:59:41 -08:00
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2019-05-13 17:16:12 -07:00
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2007-05-06 14:49:46 -07:00
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2015-02-12 14:59:41 -08:00
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2007-05-06 14:49:46 -07:00
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2015-02-12 14:59:41 -08:00
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2007-05-06 14:49:46 -07:00
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2011-08-09 16:12:22 -05:00
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2019-05-13 17:16:12 -07:00
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2011-08-09 16:12:22 -05:00
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2015-02-12 14:59:44 -08:00
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2007-05-06 14:49:46 -07:00
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2015-02-12 14:59:44 -08:00
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2007-05-06 14:49:46 -07:00
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2017-02-22 15:41:27 -08:00
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2019-07-11 20:56:09 -07:00
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2017-02-22 15:41:30 -08:00
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2017-02-22 15:41:33 -08:00
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2017-02-22 15:41:30 -08:00
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2017-02-22 15:41:27 -08:00
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2017-07-06 15:36:34 -07:00
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2017-02-22 15:41:27 -08:00
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2019-05-13 17:16:09 -07:00
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2017-02-22 15:41:27 -08:00
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2007-10-21 16:41:37 -07:00
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2012-07-06 15:25:12 -05:00
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2007-10-21 16:41:37 -07:00
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2017-02-22 15:41:27 -08:00
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2012-07-06 15:25:12 -05:00
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2007-10-21 16:41:37 -07:00
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2012-12-11 16:01:05 -08:00
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2007-10-21 16:41:37 -07:00
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2012-07-06 15:25:12 -05:00
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2007-10-21 16:41:37 -07:00
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2009-12-18 15:40:42 -05:00
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2007-10-21 16:41:37 -07:00
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2008-04-14 18:53:02 +03:00
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2007-10-21 16:41:37 -07:00
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2010-08-25 14:51:14 -05:00
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2007-10-21 16:41:37 -07:00
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2012-07-06 15:25:12 -05:00
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2007-10-21 16:41:37 -07:00
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2012-12-11 16:01:05 -08:00
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2007-10-21 16:41:37 -07:00
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2008-04-29 16:11:12 -07:00
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2007-10-21 16:41:37 -07:00
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2012-07-06 15:25:12 -05:00
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2007-10-21 16:41:37 -07:00
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2010-08-25 14:51:14 -05:00
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2007-10-21 16:41:37 -07:00
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2012-05-11 00:50:47 +09:00
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2007-10-21 16:41:37 -07:00
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2012-07-06 15:25:12 -05:00
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2007-10-21 16:41:37 -07:00
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2008-12-01 13:13:48 -08:00
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2007-10-21 16:41:37 -07:00
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2013-04-29 15:08:06 -07:00
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2007-10-21 16:41:37 -07:00
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2007-05-06 14:49:36 -07:00
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2010-08-20 12:37:15 -05:00
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2012-11-28 16:23:07 +00:00
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2010-08-20 12:37:15 -05:00
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2012-11-28 16:23:07 +00:00
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2010-08-20 12:37:15 -05:00
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2012-11-28 16:23:07 +00:00
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2014-08-06 16:04:09 -07:00
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2010-08-20 12:37:15 -05:00
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2012-11-28 16:23:07 +00:00
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2010-08-20 12:37:15 -05:00
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2013-02-22 20:20:00 +04:00
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2014-08-06 16:04:09 -07:00
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2010-08-20 12:37:15 -05:00
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2019-05-13 17:16:12 -07:00
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2014-08-06 16:04:09 -07:00
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2010-08-20 12:37:15 -05:00
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2011-04-12 15:22:26 +08:00
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2019-05-13 17:16:12 -07:00
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2014-08-06 16:04:09 -07:00
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2010-08-20 12:37:15 -05:00
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2015-02-12 14:59:20 -08:00
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2012-11-28 16:23:07 +00:00
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mm: memcg/slab: postpone kmem_cache memcg pointer initialization to memcg_link_cache()
Patch series "mm: reparent slab memory on cgroup removal", v7.
# Why do we need this?
We've noticed that the number of dying cgroups is steadily growing on most
of our hosts in production. The following investigation revealed an issue
in the userspace memory reclaim code [1], accounting of kernel stacks [2],
and also the main reason: slab objects.
The underlying problem is quite simple: any page charged to a cgroup holds
a reference to it, so the cgroup can't be reclaimed unless all charged
pages are gone. If a slab object is actively used by other cgroups, it
won't be reclaimed, and will prevent the origin cgroup from being
reclaimed.
Slab objects, and first of all vfs cache, is shared between cgroups, which
are using the same underlying fs, and what's even more important, it's
shared between multiple generations of the same workload. So if something
is running periodically every time in a new cgroup (like how systemd
works), we do accumulate multiple dying cgroups.
Strictly speaking pagecache isn't different here, but there is a key
difference: we disable protection and apply some extra pressure on LRUs of
dying cgroups, and these LRUs contain all charged pages. My experiments
show that with the disabled kernel memory accounting the number of dying
cgroups stabilizes at a relatively small number (~100, depends on memory
pressure and cgroup creation rate), and with kernel memory accounting it
grows pretty steadily up to several thousands.
Memory cgroups are quite complex and big objects (mostly due to percpu
stats), so it leads to noticeable memory losses. Memory occupied by dying
cgroups is measured in hundreds of megabytes. I've even seen a host with
more than 100Gb of memory wasted for dying cgroups. It leads to a
degradation of performance with the uptime, and generally limits the usage
of cgroups.
My previous attempt [3] to fix the problem by applying extra pressure on
slab shrinker lists caused a regressions with xfs and ext4, and has been
reverted [4]. The following attempts to find the right balance [5, 6]
were not successful.
So instead of trying to find a maybe non-existing balance, let's do
reparent accounted slab caches to the parent cgroup on cgroup removal.
# Implementation approach
There is however a significant problem with reparenting of slab memory:
there is no list of charged pages. Some of them are in shrinker lists,
but not all. Introducing of a new list is really not an option.
But fortunately there is a way forward: every slab page has a stable
pointer to the corresponding kmem_cache. So the idea is to reparent
kmem_caches instead of slab pages.
It's actually simpler and cheaper, but requires some underlying changes:
1) Make kmem_caches to hold a single reference to the memory cgroup,
instead of a separate reference per every slab page.
2) Stop setting page->mem_cgroup pointer for memcg slab pages and use
page->kmem_cache->memcg indirection instead. It's used only on
slab page release, so performance overhead shouldn't be a big issue.
3) Introduce a refcounter for non-root slab caches. It's required to
be able to destroy kmem_caches when they become empty and release
the associated memory cgroup.
There is a bonus: currently we release all memcg kmem_caches all together
with the memory cgroup itself. This patchset allows individual
kmem_caches to be released as soon as they become inactive and free.
Some additional implementation details are provided in corresponding
commit messages.
# Results
Below is the average number of dying cgroups on two groups of our
production hosts. They do run some sort of web frontend workload, the
memory pressure is moderate. As we can see, with the kernel memory
reparenting the number stabilizes in 60s range; however with the original
version it grows almost linearly and doesn't show any signs of plateauing.
The difference in slab and percpu usage between patched and unpatched
versions also grows linearly. In 7 days it exceeded 200Mb.
day 0 1 2 3 4 5 6 7
original 56 362 628 752 1070 1250 1490 1560
patched 23 46 51 55 60 57 67 69
mem diff(Mb) 22 74 123 152 164 182 214 241
# Links
[1]: commit 68600f623d69 ("mm: don't miss the last page because of round-off error")
[2]: commit 9b6f7e163cd0 ("mm: rework memcg kernel stack accounting")
[3]: commit 172b06c32b94 ("mm: slowly shrink slabs with a relatively small number of objects")
[4]: commit a9a238e83fbb ("Revert "mm: slowly shrink slabs with a relatively small number of objects")
[5]: https://lkml.org/lkml/2019/1/28/1865
[6]: https://marc.info/?l=linux-mm&m=155064763626437&w=2
This patch (of 10):
Initialize kmem_cache->memcg_params.memcg pointer in memcg_link_cache()
rather than in init_memcg_params().
Once kmem_cache will hold a reference to the memory cgroup, it will
simplify the refcounting.
For non-root kmem_caches memcg_link_cache() is always called before the
kmem_cache becomes visible to a user, so it's safe.
Link: http://lkml.kernel.org/r/20190611231813.3148843-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-11 20:56:02 -07:00
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2012-11-28 16:23:07 +00:00
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2010-08-20 12:37:15 -05:00
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2007-05-06 14:49:36 -07:00
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2012-11-28 16:23:07 +00:00
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2010-08-20 12:37:15 -05:00
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2012-01-10 15:07:32 -08:00
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2012-11-28 16:23:07 +00:00
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2010-08-20 12:37:15 -05:00
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2012-11-28 16:23:07 +00:00
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usercopy: Prepare for usercopy whitelisting
This patch prepares the slab allocator to handle caches having annotations
(useroffset and usersize) defining usercopy regions.
This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on
my understanding of the code. Changes or omissions from the original
code are mine and don't reflect the original grsecurity/PaX code.
Currently, hardened usercopy performs dynamic bounds checking on slab
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs. To further
restrict what memory is available for copying, this creates a way to
whitelist specific areas of a given slab cache object for copying to/from
userspace, allowing much finer granularity of access control. Slab caches
that are never exposed to userspace can declare no whitelist for their
objects, thereby keeping them unavailable to userspace via dynamic copy
operations. (Note, an implicit form of whitelisting is the use of constant
sizes in usercopy operations and get_user()/put_user(); these bypass
hardened usercopy checks since these sizes cannot change at runtime.)
To support this whitelist annotation, usercopy region offset and size
members are added to struct kmem_cache. The slab allocator receives a
new function, kmem_cache_create_usercopy(), that creates a new cache
with a usercopy region defined, suitable for declaring spans of fields
within the objects that get copied to/from userspace.
In this patch, the default kmem_cache_create() marks the entire allocation
as whitelisted, leaving it semantically unchanged. Once all fine-grained
whitelists have been added (in subsequent patches), this will be changed
to a usersize of 0, making caches created with kmem_cache_create() not
copyable to/from userspace.
After the entire usercopy whitelist series is applied, less than 15%
of the slab cache memory remains exposed to potential usercopy bugs
after a fresh boot:
Total Slab Memory: 48074720
Usercopyable Memory: 6367532 13.2%
task_struct 0.2% 4480/1630720
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 269760/8740224
dentry 11.1% 585984/5273856
mm_struct 29.1% 54912/188448
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 81920/81920
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 167936/167936
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 455616/455616
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 812032/812032
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1310720/1310720
After some kernel build workloads, the percentage (mainly driven by
dentry and inode caches expanding) drops under 10%:
Total Slab Memory: 95516184
Usercopyable Memory: 8497452 8.8%
task_struct 0.2% 4000/1456000
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 1217280/39439872
dentry 11.1% 1623200/14608800
mm_struct 29.1% 73216/251264
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 94208/94208
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 245760/245760
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 563520/563520
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 794624/794624
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1257472/1257472
Signed-off-by: David Windsor <dave@nullcore.net>
[kees: adjust commit log, split out a few extra kmalloc hunks]
[kees: add field names to function declarations]
[kees: convert BUGs to WARNs and fail closed]
[kees: add attack surface reduction analysis to commit log]
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christoph Lameter <cl@linux.com>
2017-06-10 22:50:28 -04:00
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2007-10-21 16:41:37 -07:00
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2013-04-29 15:08:06 -07:00
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2007-05-06 14:49:36 -07:00
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2012-11-28 16:23:07 +00:00
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usercopy: Prepare for usercopy whitelisting
This patch prepares the slab allocator to handle caches having annotations
(useroffset and usersize) defining usercopy regions.
This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on
my understanding of the code. Changes or omissions from the original
code are mine and don't reflect the original grsecurity/PaX code.
Currently, hardened usercopy performs dynamic bounds checking on slab
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs. To further
restrict what memory is available for copying, this creates a way to
whitelist specific areas of a given slab cache object for copying to/from
userspace, allowing much finer granularity of access control. Slab caches
that are never exposed to userspace can declare no whitelist for their
objects, thereby keeping them unavailable to userspace via dynamic copy
operations. (Note, an implicit form of whitelisting is the use of constant
sizes in usercopy operations and get_user()/put_user(); these bypass
hardened usercopy checks since these sizes cannot change at runtime.)
To support this whitelist annotation, usercopy region offset and size
members are added to struct kmem_cache. The slab allocator receives a
new function, kmem_cache_create_usercopy(), that creates a new cache
with a usercopy region defined, suitable for declaring spans of fields
within the objects that get copied to/from userspace.
In this patch, the default kmem_cache_create() marks the entire allocation
as whitelisted, leaving it semantically unchanged. Once all fine-grained
whitelists have been added (in subsequent patches), this will be changed
to a usersize of 0, making caches created with kmem_cache_create() not
copyable to/from userspace.
After the entire usercopy whitelist series is applied, less than 15%
of the slab cache memory remains exposed to potential usercopy bugs
after a fresh boot:
Total Slab Memory: 48074720
Usercopyable Memory: 6367532 13.2%
task_struct 0.2% 4480/1630720
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 269760/8740224
dentry 11.1% 585984/5273856
mm_struct 29.1% 54912/188448
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 81920/81920
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 167936/167936
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 455616/455616
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 812032/812032
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1310720/1310720
After some kernel build workloads, the percentage (mainly driven by
dentry and inode caches expanding) drops under 10%:
Total Slab Memory: 95516184
Usercopyable Memory: 8497452 8.8%
task_struct 0.2% 4000/1456000
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 1217280/39439872
dentry 11.1% 1623200/14608800
mm_struct 29.1% 73216/251264
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 94208/94208
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 245760/245760
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 563520/563520
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 794624/794624
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1257472/1257472
Signed-off-by: David Windsor <dave@nullcore.net>
[kees: adjust commit log, split out a few extra kmalloc hunks]
[kees: add field names to function declarations]
[kees: convert BUGs to WARNs and fail closed]
[kees: add attack surface reduction analysis to commit log]
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christoph Lameter <cl@linux.com>
2017-06-10 22:50:28 -04:00
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2012-09-04 23:18:33 +00:00
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2012-11-28 16:23:07 +00:00
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2010-08-20 12:37:15 -05:00
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2015-06-24 16:55:57 -07:00
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2013-01-10 19:12:17 +00:00
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2007-05-06 14:49:36 -07:00
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2016-07-26 15:21:59 -07:00
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2016-08-18 14:57:19 +02:00
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2007-05-06 14:49:36 -07:00
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2019-03-05 15:48:26 -08:00
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2013-01-10 19:12:17 +00:00
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2007-05-06 14:49:36 -07:00
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2009-06-12 14:03:06 +03:00
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2012-12-18 14:22:34 -08:00
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2018-04-05 16:20:37 -07:00
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2017-11-15 17:32:18 -08:00
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2007-05-06 14:49:36 -07:00
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2015-02-12 14:59:23 -08:00
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2007-05-06 14:49:36 -07:00
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memcg, slab: never try to merge memcg caches
When a kmem cache is created (kmem_cache_create_memcg()), we first try to
find a compatible cache that already exists and can handle requests from
the new cache, i.e. has the same object size, alignment, ctor, etc. If
there is such a cache, we do not create any new caches, instead we simply
increment the refcount of the cache found and return it.
Currently we do this procedure not only when creating root caches, but
also for memcg caches. However, there is no point in that, because, as
every memcg cache has exactly the same parameters as its parent and cache
merging cannot be turned off in runtime (only on boot by passing
"slub_nomerge"), the root caches of any two potentially mergeable memcg
caches should be merged already, i.e. it must be the same root cache, and
therefore we couldn't even get to the memcg cache creation, because it
already exists.
The only exception is boot caches - they are explicitly forbidden to be
merged by setting their refcount to -1. There are currently only two of
them - kmem_cache and kmem_cache_node, which are used in slab internals (I
do not count kmalloc caches as their refcount is set to 1 immediately
after creation). Since they are prevented from merging preliminary I
guess we should avoid to merge their children too.
So let's remove the useless code responsible for merging memcg caches.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Glauber Costa <glommer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 15:39:23 -07:00
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2007-05-06 14:49:36 -07:00
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2014-04-07 15:39:29 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:17 -07:00
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2018-04-05 16:21:06 -07:00
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2008-02-15 23:45:26 -08:00
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2015-02-12 14:59:23 -08:00
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2014-04-07 15:39:29 -07:00
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2018-04-05 16:21:06 -07:00
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2014-04-07 15:39:29 -07:00
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2008-12-17 22:09:46 -08:00
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2012-09-05 00:18:32 +00:00
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2008-12-17 22:09:46 -08:00
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2007-07-17 04:03:31 -07:00
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2008-02-15 23:45:26 -08:00
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2012-09-05 00:18:32 +00:00
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2010-09-14 23:21:12 +03:00
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2017-11-15 17:32:18 -08:00
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2012-09-05 00:18:32 +00:00
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2012-09-05 12:07:44 +03:00
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2012-07-06 15:25:13 -05:00
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2012-09-05 12:07:44 +03:00
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2012-07-06 15:25:13 -05:00
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2012-11-28 16:23:07 +00:00
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slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2012-09-05 12:07:44 +03:00
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2016-02-17 13:11:37 -08:00
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2012-09-05 12:07:44 +03:00
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2007-05-06 14:49:36 -07:00
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2008-08-19 20:43:25 +03:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:24:38 -07:00
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2008-08-24 20:49:35 +03:00
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2007-10-16 01:24:38 -07:00
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2013-01-10 19:14:19 +00:00
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2008-02-11 22:47:46 +02:00
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2013-01-10 19:14:19 +00:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:24:44 -07:00
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2007-07-17 04:03:22 -07:00
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2007-05-06 14:49:36 -07:00
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2012-09-08 17:47:58 -03:00
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2008-08-24 20:49:35 +03:00
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2011-03-30 22:57:33 -03:00
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2009-03-23 15:12:24 +02:00
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2008-08-24 20:49:35 +03:00
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2007-05-06 14:49:36 -07:00
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2010-09-29 21:02:15 +09:00
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2007-05-06 14:49:36 -07:00
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2008-08-19 20:43:25 +03:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:24:38 -07:00
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2008-08-24 20:49:35 +03:00
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2007-10-16 01:24:38 -07:00
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2013-01-10 19:14:19 +00:00
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2010-04-08 17:26:44 +08:00
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2008-02-11 22:47:46 +02:00
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2013-01-10 19:14:19 +00:00
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2007-05-06 14:49:36 -07:00
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2007-10-16 01:24:44 -07:00
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2007-07-17 04:03:22 -07:00
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2007-05-06 14:49:36 -07:00
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2012-09-08 17:47:58 -03:00
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2008-08-24 20:49:35 +03:00
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2011-03-30 22:57:33 -03:00
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2009-03-23 15:12:24 +02:00
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2008-08-24 20:49:35 +03:00
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2007-05-06 14:49:36 -07:00
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2010-09-29 21:02:15 +09:00
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2007-05-06 14:49:36 -07:00
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2010-10-05 13:57:26 -05:00
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2008-04-14 19:11:40 +03:00
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2010-10-05 13:57:26 -05:00
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2008-04-14 19:11:40 +03:00
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2010-10-05 13:57:26 -05:00
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2007-07-17 04:03:30 -07:00
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2007-05-06 14:49:43 -07:00
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2008-03-01 13:40:44 -08:00
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2007-05-06 14:49:43 -07:00
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2008-04-14 19:11:30 +03:00
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2007-05-06 14:49:43 -07:00
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2011-04-15 14:48:13 -05:00
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2007-05-06 14:49:43 -07:00
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2008-04-14 19:11:31 +03:00
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2007-05-09 02:32:40 -07:00
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2010-12-01 20:04:20 +02:00
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2007-05-06 14:49:43 -07:00
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2007-07-17 04:03:30 -07:00
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2007-05-06 14:49:43 -07:00
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2011-06-01 12:25:53 -05:00
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2007-05-06 14:49:43 -07:00
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2007-07-17 04:03:30 -07:00
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2007-05-06 14:49:43 -07:00
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2019-05-13 17:16:12 -07:00
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2007-07-17 04:03:30 -07:00
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2007-05-06 14:49:43 -07:00
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2014-06-04 16:06:34 -07:00
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2007-05-06 14:49:43 -07:00
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2019-05-13 17:16:12 -07:00
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2007-07-17 04:03:30 -07:00
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2007-05-06 14:49:43 -07:00
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2014-06-04 16:06:34 -07:00
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2007-05-06 14:49:43 -07:00
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2007-07-17 04:03:30 -07:00
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2007-05-06 14:49:43 -07:00
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2014-08-06 16:04:09 -07:00
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2018-10-26 15:03:06 -07:00
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2007-07-17 04:03:30 -07:00
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2007-05-06 14:49:43 -07:00
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2014-08-06 16:04:09 -07:00
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2007-07-17 04:03:30 -07:00
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2018-10-26 15:03:06 -07:00
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2007-05-06 14:49:43 -07:00
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2007-05-06 14:49:45 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:45 -07:00
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2008-08-19 20:43:25 +03:00
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2007-05-09 02:32:45 -07:00
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2009-01-01 10:12:29 +10:30
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2007-05-09 02:32:45 -07:00
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2007-05-06 14:49:45 -07:00
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2007-07-17 04:03:20 -07:00
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2007-05-06 14:49:45 -07:00
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2007-07-17 04:03:20 -07:00
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2007-05-06 14:49:45 -07:00
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2007-05-09 02:32:45 -07:00
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2007-05-06 14:49:45 -07:00
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2008-08-19 20:43:25 +03:00
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2007-05-09 02:32:45 -07:00
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2007-05-06 14:49:45 -07:00
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2007-05-09 02:32:45 -07:00
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2009-01-01 10:12:29 +10:30
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2007-05-09 02:32:45 -07:00
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2007-05-06 14:49:45 -07:00
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2007-05-09 02:32:45 -07:00
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2007-05-06 14:49:45 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:45 -07:00
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2007-07-17 04:03:20 -07:00
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2007-05-06 14:49:45 -07:00
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2007-05-09 02:32:45 -07:00
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2009-01-01 10:12:29 +10:30
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2007-05-09 02:32:45 -07:00
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2007-05-06 14:49:45 -07:00
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2010-03-24 22:25:47 +01:00
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2010-09-29 21:02:13 +09:00
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2007-05-06 14:49:45 -07:00
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2008-03-01 13:40:44 -08:00
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2007-05-06 14:49:45 -07:00
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2008-04-14 19:11:30 +03:00
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2011-04-15 14:48:13 -05:00
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2007-05-06 14:49:45 -07:00
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2008-04-14 19:11:31 +03:00
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2007-05-09 02:32:45 -07:00
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2007-05-06 14:49:45 -07:00
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2008-01-31 15:20:50 -08:00
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2007-05-06 14:49:45 -07:00
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2007-07-17 04:03:20 -07:00
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2007-05-06 14:49:45 -07:00
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2014-08-06 16:04:09 -07:00
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2018-10-26 15:03:06 -07:00
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2007-05-06 14:49:45 -07:00
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2010-03-24 22:25:47 +01:00
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2017-09-13 16:28:29 -07:00
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2018-10-26 15:03:06 -07:00
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2007-07-17 04:03:20 -07:00
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2010-03-24 22:25:47 +01:00
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2007-05-06 14:49:45 -07:00
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2014-08-06 16:04:09 -07:00
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2007-05-06 14:49:45 -07:00
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2007-08-22 14:01:56 -07:00
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2007-05-06 14:49:45 -07:00
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2019-05-13 17:16:12 -07:00
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2010-03-24 22:25:47 +01:00
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2019-05-13 17:16:12 -07:00
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2010-03-24 22:25:47 +01:00
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2007-05-06 14:49:45 -07:00
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2007-05-09 02:32:45 -07:00
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2007-05-06 14:49:45 -07:00
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2008-12-09 13:14:27 -08:00
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2007-05-06 14:49:45 -07:00
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2008-01-31 15:20:50 -08:00
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2007-05-09 02:32:45 -07:00
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2011-01-13 15:45:52 -08:00
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2007-05-06 14:49:45 -07:00
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2008-01-31 15:20:50 -08:00
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2007-05-09 02:32:45 -07:00
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2008-01-31 15:20:50 -08:00
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2008-05-01 04:34:31 -07:00
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2007-05-09 02:32:45 -07:00
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2008-01-31 15:20:50 -08:00
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2007-05-09 02:32:45 -07:00
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2008-01-31 15:20:50 -08:00
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2007-05-09 02:32:45 -07:00
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2008-01-31 15:20:50 -08:00
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2007-05-09 02:32:45 -07:00
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2009-01-01 10:12:29 +10:30
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2015-02-13 14:37:59 -08:00
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2007-05-09 02:32:45 -07:00
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2009-06-16 15:32:15 -07:00
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2015-02-13 14:37:59 -08:00
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2007-05-09 02:32:45 -07:00
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2008-01-31 15:20:50 -08:00
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2007-05-06 14:49:45 -07:00
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2018-10-26 15:03:06 -07:00
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2007-05-06 14:49:45 -07:00
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2008-01-31 15:20:50 -08:00
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2007-05-06 14:49:45 -07:00
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2019-05-13 17:16:09 -07:00
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2007-05-06 14:49:45 -07:00
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2010-10-05 13:57:27 -05:00
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2014-08-06 16:04:16 -07:00
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2010-10-05 13:57:27 -05:00
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mm, slab: combine kmalloc_caches and kmalloc_dma_caches
Patch series "kmalloc-reclaimable caches", v4.
As discussed at LSF/MM [1] here's a patchset that introduces
kmalloc-reclaimable caches (more details in the second patch) and uses
them for dcache external names. That allows us to repurpose the
NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series.
With patch 3/6, dcache external names are allocated from kmalloc-rcl-*
caches, eliminating the need for manual accounting. More importantly, it
also ensures the reclaimable kmalloc allocations are grouped in pages
separate from the regular kmalloc allocations. The need for proper
accounting of dcache external names has shown it's easy for misbehaving
process to allocate lots of them, causing premature OOMs. Without the
added grouping, it's likely that a similar workload can interleave the
dcache external names allocations with regular kmalloc allocations (note:
I haven't searched myself for an example of such regular kmalloc
allocation, but I would be very surprised if there wasn't some). A
pathological case would be e.g. one 64byte regular allocations with 63
external dcache names in a page (64x64=4096), which means the page is not
freed even after reclaiming after all dcache names, and the process can
thus "steal" the whole page with single 64byte allocation.
If other kmalloc users similar to dcache external names become identified,
they can also benefit from the new functionality simply by adding
__GFP_RECLAIMABLE to the kmalloc calls.
Side benefits of the patchset (that could be also merged separately)
include removed branch for detecting __GFP_DMA kmalloc(), and shortening
kmalloc cache names in /proc/slabinfo output. The latter is potentially
an ABI break in case there are tools parsing the names and expecting the
values to be in bytes.
This is how /proc/slabinfo looks like after booting in virtme:
...
kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
...
kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0
kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0
kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0
kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0
...
/proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter:
...
nr_slab_reclaimable 2817
nr_slab_unreclaimable 1781
...
nr_kernel_misc_reclaimable 0
...
/proc/meminfo with new KReclaimable counter:
...
Shmem: 564 kB
KReclaimable: 11260 kB
Slab: 18368 kB
SReclaimable: 11260 kB
SUnreclaim: 7108 kB
KernelStack: 1248 kB
...
This patch (of 6):
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for
__GFP_DMA in the allocation hotpaths. We can avoid the branches by
combining kmalloc_caches and kmalloc_dma_caches into a single
two-dimensional array where the outer dimension is cache "type". This
will also allow to add kmalloc-reclaimable caches as a third type.
Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 15:05:34 -07:00
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2010-10-05 13:57:27 -05:00
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2013-01-10 19:14:19 +00:00
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2010-10-05 13:57:27 -05:00
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2014-06-04 16:06:34 -07:00
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2010-10-05 13:57:27 -05:00
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2014-06-04 16:06:34 -07:00
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2010-10-05 13:57:27 -05:00
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mm, slab: combine kmalloc_caches and kmalloc_dma_caches
Patch series "kmalloc-reclaimable caches", v4.
As discussed at LSF/MM [1] here's a patchset that introduces
kmalloc-reclaimable caches (more details in the second patch) and uses
them for dcache external names. That allows us to repurpose the
NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series.
With patch 3/6, dcache external names are allocated from kmalloc-rcl-*
caches, eliminating the need for manual accounting. More importantly, it
also ensures the reclaimable kmalloc allocations are grouped in pages
separate from the regular kmalloc allocations. The need for proper
accounting of dcache external names has shown it's easy for misbehaving
process to allocate lots of them, causing premature OOMs. Without the
added grouping, it's likely that a similar workload can interleave the
dcache external names allocations with regular kmalloc allocations (note:
I haven't searched myself for an example of such regular kmalloc
allocation, but I would be very surprised if there wasn't some). A
pathological case would be e.g. one 64byte regular allocations with 63
external dcache names in a page (64x64=4096), which means the page is not
freed even after reclaiming after all dcache names, and the process can
thus "steal" the whole page with single 64byte allocation.
If other kmalloc users similar to dcache external names become identified,
they can also benefit from the new functionality simply by adding
__GFP_RECLAIMABLE to the kmalloc calls.
Side benefits of the patchset (that could be also merged separately)
include removed branch for detecting __GFP_DMA kmalloc(), and shortening
kmalloc cache names in /proc/slabinfo output. The latter is potentially
an ABI break in case there are tools parsing the names and expecting the
values to be in bytes.
This is how /proc/slabinfo looks like after booting in virtme:
...
kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
...
kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0
kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0
kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0
kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0
...
/proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter:
...
nr_slab_reclaimable 2817
nr_slab_unreclaimable 1781
...
nr_kernel_misc_reclaimable 0
...
/proc/meminfo with new KReclaimable counter:
...
Shmem: 564 kB
KReclaimable: 11260 kB
Slab: 18368 kB
SReclaimable: 11260 kB
SUnreclaim: 7108 kB
KernelStack: 1248 kB
...
This patch (of 6):
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for
__GFP_DMA in the allocation hotpaths. We can avoid the branches by
combining kmalloc_caches and kmalloc_dma_caches into a single
two-dimensional array where the outer dimension is cache "type". This
will also allow to add kmalloc-reclaimable caches as a third type.
Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 15:05:34 -07:00
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2010-10-05 13:57:27 -05:00
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2014-06-04 16:06:34 -07:00
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2010-10-05 13:57:27 -05:00
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mm, slab: combine kmalloc_caches and kmalloc_dma_caches
Patch series "kmalloc-reclaimable caches", v4.
As discussed at LSF/MM [1] here's a patchset that introduces
kmalloc-reclaimable caches (more details in the second patch) and uses
them for dcache external names. That allows us to repurpose the
NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series.
With patch 3/6, dcache external names are allocated from kmalloc-rcl-*
caches, eliminating the need for manual accounting. More importantly, it
also ensures the reclaimable kmalloc allocations are grouped in pages
separate from the regular kmalloc allocations. The need for proper
accounting of dcache external names has shown it's easy for misbehaving
process to allocate lots of them, causing premature OOMs. Without the
added grouping, it's likely that a similar workload can interleave the
dcache external names allocations with regular kmalloc allocations (note:
I haven't searched myself for an example of such regular kmalloc
allocation, but I would be very surprised if there wasn't some). A
pathological case would be e.g. one 64byte regular allocations with 63
external dcache names in a page (64x64=4096), which means the page is not
freed even after reclaiming after all dcache names, and the process can
thus "steal" the whole page with single 64byte allocation.
If other kmalloc users similar to dcache external names become identified,
they can also benefit from the new functionality simply by adding
__GFP_RECLAIMABLE to the kmalloc calls.
Side benefits of the patchset (that could be also merged separately)
include removed branch for detecting __GFP_DMA kmalloc(), and shortening
kmalloc cache names in /proc/slabinfo output. The latter is potentially
an ABI break in case there are tools parsing the names and expecting the
values to be in bytes.
This is how /proc/slabinfo looks like after booting in virtme:
...
kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
...
kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0
kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0
kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0
kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0
...
/proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter:
...
nr_slab_reclaimable 2817
nr_slab_unreclaimable 1781
...
nr_kernel_misc_reclaimable 0
...
/proc/meminfo with new KReclaimable counter:
...
Shmem: 564 kB
KReclaimable: 11260 kB
Slab: 18368 kB
SReclaimable: 11260 kB
SUnreclaim: 7108 kB
KernelStack: 1248 kB
...
This patch (of 6):
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for
__GFP_DMA in the allocation hotpaths. We can avoid the branches by
combining kmalloc_caches and kmalloc_dma_caches into a single
two-dimensional array where the outer dimension is cache "type". This
will also allow to add kmalloc-reclaimable caches as a third type.
Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 15:05:34 -07:00
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2010-10-05 13:57:27 -05:00
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2014-06-04 16:06:34 -07:00
|
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|
|
|
|
|
|
mm, slab: combine kmalloc_caches and kmalloc_dma_caches
Patch series "kmalloc-reclaimable caches", v4.
As discussed at LSF/MM [1] here's a patchset that introduces
kmalloc-reclaimable caches (more details in the second patch) and uses
them for dcache external names. That allows us to repurpose the
NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series.
With patch 3/6, dcache external names are allocated from kmalloc-rcl-*
caches, eliminating the need for manual accounting. More importantly, it
also ensures the reclaimable kmalloc allocations are grouped in pages
separate from the regular kmalloc allocations. The need for proper
accounting of dcache external names has shown it's easy for misbehaving
process to allocate lots of them, causing premature OOMs. Without the
added grouping, it's likely that a similar workload can interleave the
dcache external names allocations with regular kmalloc allocations (note:
I haven't searched myself for an example of such regular kmalloc
allocation, but I would be very surprised if there wasn't some). A
pathological case would be e.g. one 64byte regular allocations with 63
external dcache names in a page (64x64=4096), which means the page is not
freed even after reclaiming after all dcache names, and the process can
thus "steal" the whole page with single 64byte allocation.
If other kmalloc users similar to dcache external names become identified,
they can also benefit from the new functionality simply by adding
__GFP_RECLAIMABLE to the kmalloc calls.
Side benefits of the patchset (that could be also merged separately)
include removed branch for detecting __GFP_DMA kmalloc(), and shortening
kmalloc cache names in /proc/slabinfo output. The latter is potentially
an ABI break in case there are tools parsing the names and expecting the
values to be in bytes.
This is how /proc/slabinfo looks like after booting in virtme:
...
kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
...
kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0
kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0
kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0
kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0
...
/proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter:
...
nr_slab_reclaimable 2817
nr_slab_unreclaimable 1781
...
nr_kernel_misc_reclaimable 0
...
/proc/meminfo with new KReclaimable counter:
...
Shmem: 564 kB
KReclaimable: 11260 kB
Slab: 18368 kB
SReclaimable: 11260 kB
SUnreclaim: 7108 kB
KernelStack: 1248 kB
...
This patch (of 6):
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for
__GFP_DMA in the allocation hotpaths. We can avoid the branches by
combining kmalloc_caches and kmalloc_dma_caches into a single
two-dimensional array where the outer dimension is cache "type". This
will also allow to add kmalloc-reclaimable caches as a third type.
Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 15:05:34 -07:00
|
|
|
|
2010-10-05 13:57:27 -05:00
|
|
|
|
2014-06-04 16:06:34 -07:00
|
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|
|
2010-10-05 13:57:27 -05:00
|
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|
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|
|
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|
|
|
|
|
2014-06-04 16:06:34 -07:00
|
|
|
|
mm, slab: combine kmalloc_caches and kmalloc_dma_caches
Patch series "kmalloc-reclaimable caches", v4.
As discussed at LSF/MM [1] here's a patchset that introduces
kmalloc-reclaimable caches (more details in the second patch) and uses
them for dcache external names. That allows us to repurpose the
NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series.
With patch 3/6, dcache external names are allocated from kmalloc-rcl-*
caches, eliminating the need for manual accounting. More importantly, it
also ensures the reclaimable kmalloc allocations are grouped in pages
separate from the regular kmalloc allocations. The need for proper
accounting of dcache external names has shown it's easy for misbehaving
process to allocate lots of them, causing premature OOMs. Without the
added grouping, it's likely that a similar workload can interleave the
dcache external names allocations with regular kmalloc allocations (note:
I haven't searched myself for an example of such regular kmalloc
allocation, but I would be very surprised if there wasn't some). A
pathological case would be e.g. one 64byte regular allocations with 63
external dcache names in a page (64x64=4096), which means the page is not
freed even after reclaiming after all dcache names, and the process can
thus "steal" the whole page with single 64byte allocation.
If other kmalloc users similar to dcache external names become identified,
they can also benefit from the new functionality simply by adding
__GFP_RECLAIMABLE to the kmalloc calls.
Side benefits of the patchset (that could be also merged separately)
include removed branch for detecting __GFP_DMA kmalloc(), and shortening
kmalloc cache names in /proc/slabinfo output. The latter is potentially
an ABI break in case there are tools parsing the names and expecting the
values to be in bytes.
This is how /proc/slabinfo looks like after booting in virtme:
...
kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
...
kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0
kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0
kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0
kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0
...
/proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter:
...
nr_slab_reclaimable 2817
nr_slab_unreclaimable 1781
...
nr_kernel_misc_reclaimable 0
...
/proc/meminfo with new KReclaimable counter:
...
Shmem: 564 kB
KReclaimable: 11260 kB
Slab: 18368 kB
SReclaimable: 11260 kB
SUnreclaim: 7108 kB
KernelStack: 1248 kB
...
This patch (of 6):
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for
__GFP_DMA in the allocation hotpaths. We can avoid the branches by
combining kmalloc_caches and kmalloc_dma_caches into a single
two-dimensional array where the outer dimension is cache "type". This
will also allow to add kmalloc-reclaimable caches as a third type.
Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 15:05:34 -07:00
|
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|
2010-10-05 13:57:27 -05:00
|
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|
2014-06-04 16:06:34 -07:00
|
|
|
|
mm, slab: combine kmalloc_caches and kmalloc_dma_caches
Patch series "kmalloc-reclaimable caches", v4.
As discussed at LSF/MM [1] here's a patchset that introduces
kmalloc-reclaimable caches (more details in the second patch) and uses
them for dcache external names. That allows us to repurpose the
NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series.
With patch 3/6, dcache external names are allocated from kmalloc-rcl-*
caches, eliminating the need for manual accounting. More importantly, it
also ensures the reclaimable kmalloc allocations are grouped in pages
separate from the regular kmalloc allocations. The need for proper
accounting of dcache external names has shown it's easy for misbehaving
process to allocate lots of them, causing premature OOMs. Without the
added grouping, it's likely that a similar workload can interleave the
dcache external names allocations with regular kmalloc allocations (note:
I haven't searched myself for an example of such regular kmalloc
allocation, but I would be very surprised if there wasn't some). A
pathological case would be e.g. one 64byte regular allocations with 63
external dcache names in a page (64x64=4096), which means the page is not
freed even after reclaiming after all dcache names, and the process can
thus "steal" the whole page with single 64byte allocation.
If other kmalloc users similar to dcache external names become identified,
they can also benefit from the new functionality simply by adding
__GFP_RECLAIMABLE to the kmalloc calls.
Side benefits of the patchset (that could be also merged separately)
include removed branch for detecting __GFP_DMA kmalloc(), and shortening
kmalloc cache names in /proc/slabinfo output. The latter is potentially
an ABI break in case there are tools parsing the names and expecting the
values to be in bytes.
This is how /proc/slabinfo looks like after booting in virtme:
...
kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
...
kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0
kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0
kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0
kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0
...
/proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter:
...
nr_slab_reclaimable 2817
nr_slab_unreclaimable 1781
...
nr_kernel_misc_reclaimable 0
...
/proc/meminfo with new KReclaimable counter:
...
Shmem: 564 kB
KReclaimable: 11260 kB
Slab: 18368 kB
SReclaimable: 11260 kB
SUnreclaim: 7108 kB
KernelStack: 1248 kB
...
This patch (of 6):
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for
__GFP_DMA in the allocation hotpaths. We can avoid the branches by
combining kmalloc_caches and kmalloc_dma_caches into a single
two-dimensional array where the outer dimension is cache "type". This
will also allow to add kmalloc-reclaimable caches as a third type.
Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 15:05:34 -07:00
|
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2010-10-05 13:57:27 -05:00
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|
2014-06-04 16:06:34 -07:00
|
|
|
|
mm, slab: combine kmalloc_caches and kmalloc_dma_caches
Patch series "kmalloc-reclaimable caches", v4.
As discussed at LSF/MM [1] here's a patchset that introduces
kmalloc-reclaimable caches (more details in the second patch) and uses
them for dcache external names. That allows us to repurpose the
NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series.
With patch 3/6, dcache external names are allocated from kmalloc-rcl-*
caches, eliminating the need for manual accounting. More importantly, it
also ensures the reclaimable kmalloc allocations are grouped in pages
separate from the regular kmalloc allocations. The need for proper
accounting of dcache external names has shown it's easy for misbehaving
process to allocate lots of them, causing premature OOMs. Without the
added grouping, it's likely that a similar workload can interleave the
dcache external names allocations with regular kmalloc allocations (note:
I haven't searched myself for an example of such regular kmalloc
allocation, but I would be very surprised if there wasn't some). A
pathological case would be e.g. one 64byte regular allocations with 63
external dcache names in a page (64x64=4096), which means the page is not
freed even after reclaiming after all dcache names, and the process can
thus "steal" the whole page with single 64byte allocation.
If other kmalloc users similar to dcache external names become identified,
they can also benefit from the new functionality simply by adding
__GFP_RECLAIMABLE to the kmalloc calls.
Side benefits of the patchset (that could be also merged separately)
include removed branch for detecting __GFP_DMA kmalloc(), and shortening
kmalloc cache names in /proc/slabinfo output. The latter is potentially
an ABI break in case there are tools parsing the names and expecting the
values to be in bytes.
This is how /proc/slabinfo looks like after booting in virtme:
...
kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
...
kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0
kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0
kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0
kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0
...
/proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter:
...
nr_slab_reclaimable 2817
nr_slab_unreclaimable 1781
...
nr_kernel_misc_reclaimable 0
...
/proc/meminfo with new KReclaimable counter:
...
Shmem: 564 kB
KReclaimable: 11260 kB
Slab: 18368 kB
SReclaimable: 11260 kB
SUnreclaim: 7108 kB
KernelStack: 1248 kB
...
This patch (of 6):
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for
__GFP_DMA in the allocation hotpaths. We can avoid the branches by
combining kmalloc_caches and kmalloc_dma_caches into a single
two-dimensional array where the outer dimension is cache "type". This
will also allow to add kmalloc-reclaimable caches as a third type.
Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 15:05:34 -07:00
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2010-10-05 13:57:27 -05:00
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2019-05-13 17:16:09 -07:00
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2010-10-05 13:57:27 -05:00
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2010-10-05 13:57:26 -05:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2017-02-22 15:41:39 -08:00
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2008-03-02 23:28:24 +03:00
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2007-05-06 14:49:36 -07:00
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treewide: kzalloc() -> kcalloc()
The kzalloc() function has a 2-factor argument form, kcalloc(). This
patch replaces cases of:
kzalloc(a * b, gfp)
with:
kcalloc(a * b, gfp)
as well as handling cases of:
kzalloc(a * b * c, gfp)
with:
kzalloc(array3_size(a, b, c), gfp)
as it's slightly less ugly than:
kzalloc_array(array_size(a, b), c, gfp)
This does, however, attempt to ignore constant size factors like:
kzalloc(4 * 1024, gfp)
though any constants defined via macros get caught up in the conversion.
Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.
The Coccinelle script used for this was:
// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@
(
kzalloc(
- (sizeof(TYPE)) * E
+ sizeof(TYPE) * E
, ...)
|
kzalloc(
- (sizeof(THING)) * E
+ sizeof(THING) * E
, ...)
)
// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@
(
kzalloc(
- sizeof(u8) * (COUNT)
+ COUNT
, ...)
|
kzalloc(
- sizeof(__u8) * (COUNT)
+ COUNT
, ...)
|
kzalloc(
- sizeof(char) * (COUNT)
+ COUNT
, ...)
|
kzalloc(
- sizeof(unsigned char) * (COUNT)
+ COUNT
, ...)
|
kzalloc(
- sizeof(u8) * COUNT
+ COUNT
, ...)
|
kzalloc(
- sizeof(__u8) * COUNT
+ COUNT
, ...)
|
kzalloc(
- sizeof(char) * COUNT
+ COUNT
, ...)
|
kzalloc(
- sizeof(unsigned char) * COUNT
+ COUNT
, ...)
)
// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@
(
- kzalloc
+ kcalloc
(
- sizeof(TYPE) * (COUNT_ID)
+ COUNT_ID, sizeof(TYPE)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(TYPE) * COUNT_ID
+ COUNT_ID, sizeof(TYPE)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(TYPE) * (COUNT_CONST)
+ COUNT_CONST, sizeof(TYPE)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(TYPE) * COUNT_CONST
+ COUNT_CONST, sizeof(TYPE)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(THING) * (COUNT_ID)
+ COUNT_ID, sizeof(THING)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(THING) * COUNT_ID
+ COUNT_ID, sizeof(THING)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(THING) * (COUNT_CONST)
+ COUNT_CONST, sizeof(THING)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(THING) * COUNT_CONST
+ COUNT_CONST, sizeof(THING)
, ...)
)
// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@
- kzalloc
+ kcalloc
(
- SIZE * COUNT
+ COUNT, SIZE
, ...)
// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@
(
kzalloc(
- sizeof(TYPE) * (COUNT) * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
kzalloc(
- sizeof(TYPE) * (COUNT) * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
kzalloc(
- sizeof(TYPE) * COUNT * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
kzalloc(
- sizeof(TYPE) * COUNT * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
kzalloc(
- sizeof(THING) * (COUNT) * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
kzalloc(
- sizeof(THING) * (COUNT) * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
kzalloc(
- sizeof(THING) * COUNT * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
kzalloc(
- sizeof(THING) * COUNT * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
)
// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@
(
kzalloc(
- sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+ array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
, ...)
|
kzalloc(
- sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
, ...)
|
kzalloc(
- sizeof(THING1) * sizeof(THING2) * COUNT
+ array3_size(COUNT, sizeof(THING1), sizeof(THING2))
, ...)
|
kzalloc(
- sizeof(THING1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(THING1), sizeof(THING2))
, ...)
|
kzalloc(
- sizeof(TYPE1) * sizeof(THING2) * COUNT
+ array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
, ...)
|
kzalloc(
- sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
, ...)
)
// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@
(
kzalloc(
- (COUNT) * STRIDE * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kzalloc(
- COUNT * (STRIDE) * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kzalloc(
- COUNT * STRIDE * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kzalloc(
- (COUNT) * (STRIDE) * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kzalloc(
- COUNT * (STRIDE) * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kzalloc(
- (COUNT) * STRIDE * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kzalloc(
- (COUNT) * (STRIDE) * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kzalloc(
- COUNT * STRIDE * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
)
// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@
(
kzalloc(C1 * C2 * C3, ...)
|
kzalloc(
- (E1) * E2 * E3
+ array3_size(E1, E2, E3)
, ...)
|
kzalloc(
- (E1) * (E2) * E3
+ array3_size(E1, E2, E3)
, ...)
|
kzalloc(
- (E1) * (E2) * (E3)
+ array3_size(E1, E2, E3)
, ...)
|
kzalloc(
- E1 * E2 * E3
+ array3_size(E1, E2, E3)
, ...)
)
// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@
(
kzalloc(sizeof(THING) * C2, ...)
|
kzalloc(sizeof(TYPE) * C2, ...)
|
kzalloc(C1 * C2 * C3, ...)
|
kzalloc(C1 * C2, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(TYPE) * (E2)
+ E2, sizeof(TYPE)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(TYPE) * E2
+ E2, sizeof(TYPE)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(THING) * (E2)
+ E2, sizeof(THING)
, ...)
|
- kzalloc
+ kcalloc
(
- sizeof(THING) * E2
+ E2, sizeof(THING)
, ...)
|
- kzalloc
+ kcalloc
(
- (E1) * E2
+ E1, E2
, ...)
|
- kzalloc
+ kcalloc
(
- (E1) * (E2)
+ E1, E2
, ...)
|
- kzalloc
+ kcalloc
(
- E1 * E2
+ E1, E2
, ...)
)
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-12 14:03:40 -07:00
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2008-03-02 23:28:24 +03:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2013-07-15 09:05:29 +08:00
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2012-05-09 10:09:56 -05:00
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2011-08-09 16:12:27 -05:00
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2007-10-16 01:26:05 -07:00
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2015-04-15 16:14:08 -07:00
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2012-05-09 10:09:56 -05:00
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2008-04-14 19:11:40 +03:00
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2012-05-09 10:09:56 -05:00
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2011-08-09 16:12:27 -05:00
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2012-05-09 10:09:56 -05:00
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2017-07-06 15:36:31 -07:00
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2011-08-09 16:12:27 -05:00
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2013-09-10 11:43:37 +08:00
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2011-11-22 16:02:02 +01:00
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2011-08-09 16:12:27 -05:00
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2007-05-06 14:49:36 -07:00
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mem-hotplug: implement get/put_online_mems
kmem_cache_{create,destroy,shrink} need to get a stable value of
cpu/node online mask, because they init/destroy/access per-cpu/node
kmem_cache parts, which can be allocated or destroyed on cpu/mem
hotplug. To protect against cpu hotplug, these functions use
{get,put}_online_cpus. However, they do nothing to synchronize with
memory hotplug - taking the slab_mutex does not eliminate the
possibility of race as described in patch 2.
What we need there is something like get_online_cpus, but for memory.
We already have lock_memory_hotplug, which serves for the purpose, but
it's a bit of a hammer right now, because it's backed by a mutex. As a
result, it imposes some limitations to locking order, which are not
desirable, and can't be used just like get_online_cpus. That's why in
patch 1 I substitute it with get/put_online_mems, which work exactly
like get/put_online_cpus except they block not cpu, but memory hotplug.
[ v1 can be found at https://lkml.org/lkml/2014/4/6/68. I NAK'ed it by
myself, because it used an rw semaphore for get/put_online_mems,
making them dead lock prune. ]
This patch (of 2):
{un}lock_memory_hotplug, which is used to synchronize against memory
hotplug, is currently backed by a mutex, which makes it a bit of a
hammer - threads that only want to get a stable value of online nodes
mask won't be able to proceed concurrently. Also, it imposes some
strong locking ordering rules on it, which narrows down the set of its
usage scenarios.
This patch introduces get/put_online_mems, which are the same as
get/put_online_cpus, but for memory hotplug, i.e. executing a code
inside a get/put_online_mems section will guarantee a stable value of
online nodes, present pages, etc.
lock_memory_hotplug()/unlock_memory_hotplug() are removed altogether.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:07:18 -07:00
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2010-10-05 13:57:26 -05:00
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2008-04-14 19:11:40 +03:00
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2014-08-06 16:04:09 -07:00
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2007-05-06 14:49:36 -07:00
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2013-07-15 09:05:29 +08:00
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2008-04-14 19:11:40 +03:00
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2010-10-05 13:57:26 -05:00
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2014-08-06 16:04:09 -07:00
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2008-04-14 19:11:40 +03:00
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2014-08-06 16:04:09 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2014-08-06 16:04:09 -07:00
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2007-05-06 14:49:36 -07:00
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mem-hotplug: implement get/put_online_mems
kmem_cache_{create,destroy,shrink} need to get a stable value of
cpu/node online mask, because they init/destroy/access per-cpu/node
kmem_cache parts, which can be allocated or destroyed on cpu/mem
hotplug. To protect against cpu hotplug, these functions use
{get,put}_online_cpus. However, they do nothing to synchronize with
memory hotplug - taking the slab_mutex does not eliminate the
possibility of race as described in patch 2.
What we need there is something like get_online_cpus, but for memory.
We already have lock_memory_hotplug, which serves for the purpose, but
it's a bit of a hammer right now, because it's backed by a mutex. As a
result, it imposes some limitations to locking order, which are not
desirable, and can't be used just like get_online_cpus. That's why in
patch 1 I substitute it with get/put_online_mems, which work exactly
like get/put_online_cpus except they block not cpu, but memory hotplug.
[ v1 can be found at https://lkml.org/lkml/2014/4/6/68. I NAK'ed it by
myself, because it used an rw semaphore for get/put_online_mems,
making them dead lock prune. ]
This patch (of 2):
{un}lock_memory_hotplug, which is used to synchronize against memory
hotplug, is currently backed by a mutex, which makes it a bit of a
hammer - threads that only want to get a stable value of online nodes
mask won't be able to proceed concurrently. Also, it imposes some
strong locking ordering rules on it, which narrows down the set of its
usage scenarios.
This patch introduces get/put_online_mems, which are the same as
get/put_online_cpus, but for memory hotplug, i.e. executing a code
inside a get/put_online_mems section will guarantee a stable value of
online nodes, present pages, etc.
lock_memory_hotplug()/unlock_memory_hotplug() are removed altogether.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:07:18 -07:00
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2007-05-06 14:49:36 -07:00
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2010-10-05 13:57:26 -05:00
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2007-05-06 14:49:36 -07:00
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2014-08-06 16:04:09 -07:00
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2007-10-16 01:26:05 -07:00
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2014-08-06 16:04:09 -07:00
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2008-05-06 20:42:39 -07:00
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2007-05-06 14:49:36 -07:00
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2014-08-06 16:04:09 -07:00
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2007-05-06 14:49:36 -07:00
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2010-10-05 13:57:26 -05:00
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2007-05-06 14:49:36 -07:00
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2011-07-14 15:07:13 +03:00
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2007-05-06 14:49:36 -07:00
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mm: restrict access to slab files under procfs and sysfs
Historically /proc/slabinfo and files under /sys/kernel/slab/* have
world read permissions and are accessible to the world. slabinfo
contains rather private information related both to the kernel and
userspace tasks. Depending on the situation, it might reveal either
private information per se or information useful to make another
targeted attack. Some examples of what can be learned by
reading/watching for /proc/slabinfo entries:
1) dentry (and different *inode*) number might reveal other processes fs
activity. The number of dentry "active objects" doesn't strictly show
file count opened/touched by a process, however, there is a good
correlation between them. The patch "proc: force dcache drop on
unauthorized access" relies on the privacy of dentry count.
2) different inode entries might reveal the same information as (1), but
these are more fine granted counters. If a filesystem is mounted in a
private mount point (or even a private namespace) and fs type differs from
other mounted fs types, fs activity in this mount point/namespace is
revealed. If there is a single ecryptfs mount point, the whole fs
activity of a single user is revealed. Number of files in ecryptfs
mount point is a private information per se.
3) fuse_* reveals number of files / fs activity of a user in a user
private mount point. It is approx. the same severity as ecryptfs
infoleak in (2).
4) sysfs_dir_cache similar to (2) reveals devices' addition/removal,
which can be otherwise hidden by "chmod 0700 /sys/". With 0444 slabinfo
the precise number of sysfs files is known to the world.
5) buffer_head might reveal some kernel activity. With other
information leaks an attacker might identify what specific kernel
routines generate buffer_head activity.
6) *kmalloc* infoleaks are very situational. Attacker should watch for
the specific kmalloc size entry and filter the noise related to the unrelated
kernel activity. If an attacker has relatively silent victim system, he
might get rather precise counters.
Additional information sources might significantly increase the slabinfo
infoleak benefits. E.g. if an attacker knows that the processes
activity on the system is very low (only core daemons like syslog and
cron), he may run setxid binaries / trigger local daemon activity /
trigger network services activity / await sporadic cron jobs activity
/ etc. and get rather precise counters for fs and network activity of
these privileged tasks, which is unknown otherwise.
Also hiding slabinfo and /sys/kernel/slab/* is a one step to complicate
exploitation of kernel heap overflows (and possibly, other bugs). The
related discussion:
http://thread.gmane.org/gmane.linux.kernel/1108378
To keep compatibility with old permission model where non-root
monitoring daemon could watch for kernel memleaks though slabinfo one
should do:
groupadd slabinfo
usermod -a -G slabinfo $MONITOR_USER
And add the following commands to init scripts (to mountall.conf in
Ubuntu's upstart case):
chmod g+r /proc/slabinfo /sys/kernel/slab/*/*
chgrp slabinfo /proc/slabinfo /sys/kernel/slab/*/*
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Reviewed-by: Kees Cook <kees@ubuntu.com>
Reviewed-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: David Rientjes <rientjes@google.com>
CC: Valdis.Kletnieks@vt.edu
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Alan Cox <alan@linux.intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-27 21:54:53 +04:00
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2007-05-06 14:49:36 -07:00
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|
mm: restrict access to slab files under procfs and sysfs
Historically /proc/slabinfo and files under /sys/kernel/slab/* have
world read permissions and are accessible to the world. slabinfo
contains rather private information related both to the kernel and
userspace tasks. Depending on the situation, it might reveal either
private information per se or information useful to make another
targeted attack. Some examples of what can be learned by
reading/watching for /proc/slabinfo entries:
1) dentry (and different *inode*) number might reveal other processes fs
activity. The number of dentry "active objects" doesn't strictly show
file count opened/touched by a process, however, there is a good
correlation between them. The patch "proc: force dcache drop on
unauthorized access" relies on the privacy of dentry count.
2) different inode entries might reveal the same information as (1), but
these are more fine granted counters. If a filesystem is mounted in a
private mount point (or even a private namespace) and fs type differs from
other mounted fs types, fs activity in this mount point/namespace is
revealed. If there is a single ecryptfs mount point, the whole fs
activity of a single user is revealed. Number of files in ecryptfs
mount point is a private information per se.
3) fuse_* reveals number of files / fs activity of a user in a user
private mount point. It is approx. the same severity as ecryptfs
infoleak in (2).
4) sysfs_dir_cache similar to (2) reveals devices' addition/removal,
which can be otherwise hidden by "chmod 0700 /sys/". With 0444 slabinfo
the precise number of sysfs files is known to the world.
5) buffer_head might reveal some kernel activity. With other
information leaks an attacker might identify what specific kernel
routines generate buffer_head activity.
6) *kmalloc* infoleaks are very situational. Attacker should watch for
the specific kmalloc size entry and filter the noise related to the unrelated
kernel activity. If an attacker has relatively silent victim system, he
might get rather precise counters.
Additional information sources might significantly increase the slabinfo
infoleak benefits. E.g. if an attacker knows that the processes
activity on the system is very low (only core daemons like syslog and
cron), he may run setxid binaries / trigger local daemon activity /
trigger network services activity / await sporadic cron jobs activity
/ etc. and get rather precise counters for fs and network activity of
these privileged tasks, which is unknown otherwise.
Also hiding slabinfo and /sys/kernel/slab/* is a one step to complicate
exploitation of kernel heap overflows (and possibly, other bugs). The
related discussion:
http://thread.gmane.org/gmane.linux.kernel/1108378
To keep compatibility with old permission model where non-root
monitoring daemon could watch for kernel memleaks though slabinfo one
should do:
groupadd slabinfo
usermod -a -G slabinfo $MONITOR_USER
And add the following commands to init scripts (to mountall.conf in
Ubuntu's upstart case):
chmod g+r /proc/slabinfo /sys/kernel/slab/*/*
chgrp slabinfo /proc/slabinfo /sys/kernel/slab/*/*
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Reviewed-by: Kees Cook <kees@ubuntu.com>
Reviewed-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: David Rientjes <rientjes@google.com>
CC: Valdis.Kletnieks@vt.edu
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Alan Cox <alan@linux.intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-27 21:54:53 +04:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:20 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:02 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:17 -07:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:41 +03:00
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2018-04-05 16:21:39 -07:00
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2008-04-29 16:11:12 -07:00
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2018-04-05 16:21:39 -07:00
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2008-04-29 16:11:12 -07:00
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2008-04-14 19:11:41 +03:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:39 -07:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:41 +03:00
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2007-05-06 14:49:36 -07:00
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slub: add min_partial sysfs tunable
Now that a cache's min_partial has been moved to struct kmem_cache, it's
possible to easily tune it from userspace by adding a sysfs attribute.
It may not be desirable to keep a large number of partial slabs around
if a cache is used infrequently and memory, especially when constrained
by a cgroup, is scarce. It's better to allow userspace to set the
minimum policy per cache instead of relying explicitly on
kmem_cache_shrink().
The memory savings from simply moving min_partial from struct
kmem_cache_node to struct kmem_cache is obviously not significant
(unless maybe you're from SGI or something), at the largest it's
# allocated caches * (MAX_NUMNODES - 1) * sizeof(unsigned long)
The true savings occurs when userspace reduces the number of partial
slabs that would otherwise be wasted, especially on machines with a
large number of nodes (ia64 with CONFIG_NODES_SHIFT at 10 for default?).
As well as the kernel estimates ideal values for n->min_partial and
ensures it's within a sane range, userspace has no other input other
than writing to /sys/kernel/slab/cache/shrink.
There simply isn't any better heuristic to add when calculating the
partial values for a better estimate that works for all possible caches.
And since it's currently a static value, the user really has no way of
reclaiming that wasted space, which can be significant when constrained
by a cgroup (either cpusets or, later, memory controller slab limits)
without shrinking it entirely.
This also allows the user to specify that increased fragmentation and
more partial slabs are actually desired to avoid the cost of allocating
new slabs at runtime for specific caches.
There's also no reason why this should be a per-struct kmem_cache_node
value in the first place. You could argue that a machine would have
such node size asymmetries that it should be specified on a per-node
basis, but we know nobody is doing that right now since it's a purely
static value at the moment and there's no convenient way to tune that
via slub's sysfs interface.
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-02-22 17:40:09 -08:00
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2013-09-11 14:20:25 -07:00
|
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|
slub: add min_partial sysfs tunable
Now that a cache's min_partial has been moved to struct kmem_cache, it's
possible to easily tune it from userspace by adding a sysfs attribute.
It may not be desirable to keep a large number of partial slabs around
if a cache is used infrequently and memory, especially when constrained
by a cgroup, is scarce. It's better to allow userspace to set the
minimum policy per cache instead of relying explicitly on
kmem_cache_shrink().
The memory savings from simply moving min_partial from struct
kmem_cache_node to struct kmem_cache is obviously not significant
(unless maybe you're from SGI or something), at the largest it's
# allocated caches * (MAX_NUMNODES - 1) * sizeof(unsigned long)
The true savings occurs when userspace reduces the number of partial
slabs that would otherwise be wasted, especially on machines with a
large number of nodes (ia64 with CONFIG_NODES_SHIFT at 10 for default?).
As well as the kernel estimates ideal values for n->min_partial and
ensures it's within a sane range, userspace has no other input other
than writing to /sys/kernel/slab/cache/shrink.
There simply isn't any better heuristic to add when calculating the
partial values for a better estimate that works for all possible caches.
And since it's currently a static value, the user really has no way of
reclaiming that wasted space, which can be significant when constrained
by a cgroup (either cpusets or, later, memory controller slab limits)
without shrinking it entirely.
This also allows the user to specify that increased fragmentation and
more partial slabs are actually desired to avoid the cost of allocating
new slabs at runtime for specific caches.
There's also no reason why this should be a per-struct kmem_cache_node
value in the first place. You could argue that a machine would have
such node size asymmetries that it should be specified on a per-node
basis, but we know nobody is doing that right now since it's a purely
static value at the moment and there's no convenient way to tune that
via slub's sysfs interface.
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-02-22 17:40:09 -08:00
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|
|
2009-02-25 09:16:35 +02:00
|
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|
|
slub: add min_partial sysfs tunable
Now that a cache's min_partial has been moved to struct kmem_cache, it's
possible to easily tune it from userspace by adding a sysfs attribute.
It may not be desirable to keep a large number of partial slabs around
if a cache is used infrequently and memory, especially when constrained
by a cgroup, is scarce. It's better to allow userspace to set the
minimum policy per cache instead of relying explicitly on
kmem_cache_shrink().
The memory savings from simply moving min_partial from struct
kmem_cache_node to struct kmem_cache is obviously not significant
(unless maybe you're from SGI or something), at the largest it's
# allocated caches * (MAX_NUMNODES - 1) * sizeof(unsigned long)
The true savings occurs when userspace reduces the number of partial
slabs that would otherwise be wasted, especially on machines with a
large number of nodes (ia64 with CONFIG_NODES_SHIFT at 10 for default?).
As well as the kernel estimates ideal values for n->min_partial and
ensures it's within a sane range, userspace has no other input other
than writing to /sys/kernel/slab/cache/shrink.
There simply isn't any better heuristic to add when calculating the
partial values for a better estimate that works for all possible caches.
And since it's currently a static value, the user really has no way of
reclaiming that wasted space, which can be significant when constrained
by a cgroup (either cpusets or, later, memory controller slab limits)
without shrinking it entirely.
This also allows the user to specify that increased fragmentation and
more partial slabs are actually desired to avoid the cost of allocating
new slabs at runtime for specific caches.
There's also no reason why this should be a per-struct kmem_cache_node
value in the first place. You could argue that a machine would have
such node size asymmetries that it should be specified on a per-node
basis, but we know nobody is doing that right now since it's a purely
static value at the moment and there's no convenient way to tune that
via slub's sysfs interface.
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-02-22 17:40:09 -08:00
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2011-08-09 16:12:27 -05:00
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2017-07-06 15:36:34 -07:00
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2011-08-09 16:12:27 -05:00
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2018-04-05 16:21:10 -07:00
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2011-08-09 16:12:27 -05:00
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2018-04-05 16:21:10 -07:00
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2011-08-09 16:12:27 -05:00
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2013-06-19 14:05:52 +09:00
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2012-01-09 13:19:45 -08:00
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2011-08-09 16:12:27 -05:00
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2017-07-06 15:36:34 -07:00
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2011-08-09 16:12:27 -05:00
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2007-05-06 14:49:36 -07:00
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2011-01-13 15:45:52 -08:00
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2007-05-06 14:49:36 -07:00
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2014-08-06 16:04:51 -07:00
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2007-05-06 14:49:36 -07:00
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2008-02-15 15:22:21 -08:00
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2007-05-06 14:49:36 -07:00
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2008-02-15 15:22:21 -08:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2011-08-09 16:12:27 -05:00
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2017-07-06 15:36:31 -07:00
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2011-08-09 16:12:27 -05:00
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2017-07-06 15:36:31 -07:00
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2011-08-09 16:12:27 -05:00
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2007-05-06 14:49:36 -07:00
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2007-05-06 14:49:56 -07:00
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2007-05-06 14:49:36 -07:00
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usercopy: Prepare for usercopy whitelisting
This patch prepares the slab allocator to handle caches having annotations
(useroffset and usersize) defining usercopy regions.
This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on
my understanding of the code. Changes or omissions from the original
code are mine and don't reflect the original grsecurity/PaX code.
Currently, hardened usercopy performs dynamic bounds checking on slab
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs. To further
restrict what memory is available for copying, this creates a way to
whitelist specific areas of a given slab cache object for copying to/from
userspace, allowing much finer granularity of access control. Slab caches
that are never exposed to userspace can declare no whitelist for their
objects, thereby keeping them unavailable to userspace via dynamic copy
operations. (Note, an implicit form of whitelisting is the use of constant
sizes in usercopy operations and get_user()/put_user(); these bypass
hardened usercopy checks since these sizes cannot change at runtime.)
To support this whitelist annotation, usercopy region offset and size
members are added to struct kmem_cache. The slab allocator receives a
new function, kmem_cache_create_usercopy(), that creates a new cache
with a usercopy region defined, suitable for declaring spans of fields
within the objects that get copied to/from userspace.
In this patch, the default kmem_cache_create() marks the entire allocation
as whitelisted, leaving it semantically unchanged. Once all fine-grained
whitelists have been added (in subsequent patches), this will be changed
to a usersize of 0, making caches created with kmem_cache_create() not
copyable to/from userspace.
After the entire usercopy whitelist series is applied, less than 15%
of the slab cache memory remains exposed to potential usercopy bugs
after a fresh boot:
Total Slab Memory: 48074720
Usercopyable Memory: 6367532 13.2%
task_struct 0.2% 4480/1630720
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 269760/8740224
dentry 11.1% 585984/5273856
mm_struct 29.1% 54912/188448
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 81920/81920
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 167936/167936
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 455616/455616
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 812032/812032
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1310720/1310720
After some kernel build workloads, the percentage (mainly driven by
dentry and inode caches expanding) drops under 10%:
Total Slab Memory: 95516184
Usercopyable Memory: 8497452 8.8%
task_struct 0.2% 4000/1456000
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 1217280/39439872
dentry 11.1% 1623200/14608800
mm_struct 29.1% 73216/251264
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 94208/94208
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 245760/245760
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 563520/563520
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 794624/794624
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1257472/1257472
Signed-off-by: David Windsor <dave@nullcore.net>
[kees: adjust commit log, split out a few extra kmalloc hunks]
[kees: add field names to function declarations]
[kees: convert BUGs to WARNs and fail closed]
[kees: add attack surface reduction analysis to commit log]
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christoph Lameter <cl@linux.com>
2017-06-10 22:50:28 -04:00
|
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|
|
2018-04-05 16:21:31 -07:00
|
|
|
|
usercopy: Prepare for usercopy whitelisting
This patch prepares the slab allocator to handle caches having annotations
(useroffset and usersize) defining usercopy regions.
This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on
my understanding of the code. Changes or omissions from the original
code are mine and don't reflect the original grsecurity/PaX code.
Currently, hardened usercopy performs dynamic bounds checking on slab
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs. To further
restrict what memory is available for copying, this creates a way to
whitelist specific areas of a given slab cache object for copying to/from
userspace, allowing much finer granularity of access control. Slab caches
that are never exposed to userspace can declare no whitelist for their
objects, thereby keeping them unavailable to userspace via dynamic copy
operations. (Note, an implicit form of whitelisting is the use of constant
sizes in usercopy operations and get_user()/put_user(); these bypass
hardened usercopy checks since these sizes cannot change at runtime.)
To support this whitelist annotation, usercopy region offset and size
members are added to struct kmem_cache. The slab allocator receives a
new function, kmem_cache_create_usercopy(), that creates a new cache
with a usercopy region defined, suitable for declaring spans of fields
within the objects that get copied to/from userspace.
In this patch, the default kmem_cache_create() marks the entire allocation
as whitelisted, leaving it semantically unchanged. Once all fine-grained
whitelists have been added (in subsequent patches), this will be changed
to a usersize of 0, making caches created with kmem_cache_create() not
copyable to/from userspace.
After the entire usercopy whitelist series is applied, less than 15%
of the slab cache memory remains exposed to potential usercopy bugs
after a fresh boot:
Total Slab Memory: 48074720
Usercopyable Memory: 6367532 13.2%
task_struct 0.2% 4480/1630720
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 269760/8740224
dentry 11.1% 585984/5273856
mm_struct 29.1% 54912/188448
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 81920/81920
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 167936/167936
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 455616/455616
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 812032/812032
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1310720/1310720
After some kernel build workloads, the percentage (mainly driven by
dentry and inode caches expanding) drops under 10%:
Total Slab Memory: 95516184
Usercopyable Memory: 8497452 8.8%
task_struct 0.2% 4000/1456000
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 1217280/39439872
dentry 11.1% 1623200/14608800
mm_struct 29.1% 73216/251264
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 94208/94208
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 245760/245760
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 563520/563520
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 794624/794624
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1257472/1257472
Signed-off-by: David Windsor <dave@nullcore.net>
[kees: adjust commit log, split out a few extra kmalloc hunks]
[kees: add field names to function declarations]
[kees: convert BUGs to WARNs and fail closed]
[kees: add attack surface reduction analysis to commit log]
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christoph Lameter <cl@linux.com>
2017-06-10 22:50:28 -04:00
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2007-05-06 14:49:36 -07:00
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2017-01-18 02:53:44 -08:00
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2007-05-06 14:49:36 -07:00
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2010-10-05 13:57:26 -05:00
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2010-10-05 13:57:27 -05:00
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2016-03-15 14:55:06 -07:00
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2010-10-05 13:57:27 -05:00
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2016-03-15 14:55:06 -07:00
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2011-06-01 12:25:49 -05:00
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2016-03-15 14:55:06 -07:00
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2011-06-01 12:25:49 -05:00
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2010-10-05 13:57:27 -05:00
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2014-10-09 15:26:11 -07:00
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2010-10-05 13:57:27 -05:00
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2011-06-01 12:25:49 -05:00
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2010-10-05 13:57:27 -05:00
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2011-06-01 12:25:49 -05:00
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2010-10-05 13:57:27 -05:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:49 -05:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:49 -05:00
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2008-04-14 19:11:41 +03:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:49 -05:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:49 -05:00
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2008-04-14 19:11:41 +03:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:49 -05:00
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2007-05-06 14:49:36 -07:00
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2011-06-01 12:25:49 -05:00
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2008-04-14 19:11:41 +03:00
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2007-05-06 14:49:36 -07:00
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2007-05-06 14:49:43 -07:00
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2007-07-17 04:03:30 -07:00
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2007-05-06 14:49:43 -07:00
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2010-10-05 13:57:27 -05:00
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2014-10-09 15:26:11 -07:00
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2010-10-05 13:57:27 -05:00
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2010-10-05 13:57:26 -05:00
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2007-05-06 14:49:43 -07:00
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2007-05-06 14:49:46 -07:00
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2015-02-12 14:59:41 -08:00
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2007-05-06 14:49:46 -07:00
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2007-05-06 14:49:36 -07:00
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2008-01-07 23:20:26 -08:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:20:48 -07:00
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2007-05-06 14:49:36 -07:00
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2008-01-07 23:20:26 -08:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:20:48 -07:00
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2008-04-29 16:11:12 -07:00
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2018-04-05 16:20:48 -07:00
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2008-04-29 16:11:12 -07:00
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2018-04-05 16:20:48 -07:00
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2008-04-29 16:11:12 -07:00
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2018-04-05 16:20:48 -07:00
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2007-05-06 14:49:36 -07:00
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2008-01-07 23:20:26 -08:00
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2007-05-06 14:49:36 -07:00
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2008-02-07 17:47:41 -08:00
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treewide: kmalloc() -> kmalloc_array()
The kmalloc() function has a 2-factor argument form, kmalloc_array(). This
patch replaces cases of:
kmalloc(a * b, gfp)
with:
kmalloc_array(a * b, gfp)
as well as handling cases of:
kmalloc(a * b * c, gfp)
with:
kmalloc(array3_size(a, b, c), gfp)
as it's slightly less ugly than:
kmalloc_array(array_size(a, b), c, gfp)
This does, however, attempt to ignore constant size factors like:
kmalloc(4 * 1024, gfp)
though any constants defined via macros get caught up in the conversion.
Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.
The tools/ directory was manually excluded, since it has its own
implementation of kmalloc().
The Coccinelle script used for this was:
// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@
(
kmalloc(
- (sizeof(TYPE)) * E
+ sizeof(TYPE) * E
, ...)
|
kmalloc(
- (sizeof(THING)) * E
+ sizeof(THING) * E
, ...)
)
// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@
(
kmalloc(
- sizeof(u8) * (COUNT)
+ COUNT
, ...)
|
kmalloc(
- sizeof(__u8) * (COUNT)
+ COUNT
, ...)
|
kmalloc(
- sizeof(char) * (COUNT)
+ COUNT
, ...)
|
kmalloc(
- sizeof(unsigned char) * (COUNT)
+ COUNT
, ...)
|
kmalloc(
- sizeof(u8) * COUNT
+ COUNT
, ...)
|
kmalloc(
- sizeof(__u8) * COUNT
+ COUNT
, ...)
|
kmalloc(
- sizeof(char) * COUNT
+ COUNT
, ...)
|
kmalloc(
- sizeof(unsigned char) * COUNT
+ COUNT
, ...)
)
// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@
(
- kmalloc
+ kmalloc_array
(
- sizeof(TYPE) * (COUNT_ID)
+ COUNT_ID, sizeof(TYPE)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(TYPE) * COUNT_ID
+ COUNT_ID, sizeof(TYPE)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(TYPE) * (COUNT_CONST)
+ COUNT_CONST, sizeof(TYPE)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(TYPE) * COUNT_CONST
+ COUNT_CONST, sizeof(TYPE)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(THING) * (COUNT_ID)
+ COUNT_ID, sizeof(THING)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(THING) * COUNT_ID
+ COUNT_ID, sizeof(THING)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(THING) * (COUNT_CONST)
+ COUNT_CONST, sizeof(THING)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(THING) * COUNT_CONST
+ COUNT_CONST, sizeof(THING)
, ...)
)
// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@
- kmalloc
+ kmalloc_array
(
- SIZE * COUNT
+ COUNT, SIZE
, ...)
// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@
(
kmalloc(
- sizeof(TYPE) * (COUNT) * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
kmalloc(
- sizeof(TYPE) * (COUNT) * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
kmalloc(
- sizeof(TYPE) * COUNT * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
kmalloc(
- sizeof(TYPE) * COUNT * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
kmalloc(
- sizeof(THING) * (COUNT) * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
kmalloc(
- sizeof(THING) * (COUNT) * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
kmalloc(
- sizeof(THING) * COUNT * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
kmalloc(
- sizeof(THING) * COUNT * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
)
// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@
(
kmalloc(
- sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+ array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
, ...)
|
kmalloc(
- sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
, ...)
|
kmalloc(
- sizeof(THING1) * sizeof(THING2) * COUNT
+ array3_size(COUNT, sizeof(THING1), sizeof(THING2))
, ...)
|
kmalloc(
- sizeof(THING1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(THING1), sizeof(THING2))
, ...)
|
kmalloc(
- sizeof(TYPE1) * sizeof(THING2) * COUNT
+ array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
, ...)
|
kmalloc(
- sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
, ...)
)
// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@
(
kmalloc(
- (COUNT) * STRIDE * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kmalloc(
- COUNT * (STRIDE) * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kmalloc(
- COUNT * STRIDE * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kmalloc(
- (COUNT) * (STRIDE) * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kmalloc(
- COUNT * (STRIDE) * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kmalloc(
- (COUNT) * STRIDE * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kmalloc(
- (COUNT) * (STRIDE) * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
kmalloc(
- COUNT * STRIDE * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
)
// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@
(
kmalloc(C1 * C2 * C3, ...)
|
kmalloc(
- (E1) * E2 * E3
+ array3_size(E1, E2, E3)
, ...)
|
kmalloc(
- (E1) * (E2) * E3
+ array3_size(E1, E2, E3)
, ...)
|
kmalloc(
- (E1) * (E2) * (E3)
+ array3_size(E1, E2, E3)
, ...)
|
kmalloc(
- E1 * E2 * E3
+ array3_size(E1, E2, E3)
, ...)
)
// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@
(
kmalloc(sizeof(THING) * C2, ...)
|
kmalloc(sizeof(TYPE) * C2, ...)
|
kmalloc(C1 * C2 * C3, ...)
|
kmalloc(C1 * C2, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(TYPE) * (E2)
+ E2, sizeof(TYPE)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(TYPE) * E2
+ E2, sizeof(TYPE)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(THING) * (E2)
+ E2, sizeof(THING)
, ...)
|
- kmalloc
+ kmalloc_array
(
- sizeof(THING) * E2
+ E2, sizeof(THING)
, ...)
|
- kmalloc
+ kmalloc_array
(
- (E1) * E2
+ E1, E2
, ...)
|
- kmalloc
+ kmalloc_array
(
- (E1) * (E2)
+ E1, E2
, ...)
|
- kmalloc
+ kmalloc_array
(
- E1 * E2
+ E1, E2
, ...)
)
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-12 13:55:00 -07:00
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2008-02-07 17:47:41 -08:00
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2009-12-18 16:26:20 -06:00
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2008-02-07 17:47:41 -08:00
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2008-04-14 18:52:05 +03:00
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2008-02-07 17:47:41 -08:00
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2008-04-14 18:52:05 +03:00
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2008-02-07 17:47:41 -08:00
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2008-04-14 18:52:05 +03:00
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2008-02-07 17:47:41 -08:00
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2009-10-15 02:20:22 -07:00
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2009-12-18 16:26:20 -06:00
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2009-10-15 02:20:22 -07:00
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2008-02-07 17:47:41 -08:00
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2009-10-15 02:20:22 -07:00
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2008-02-07 17:47:41 -08:00
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2011-06-01 12:25:57 -05:00
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2008-02-07 17:47:41 -08:00
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2011-06-01 12:25:58 -05:00
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2008-04-14 19:11:40 +03:00
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2011-06-01 12:25:49 -05:00
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2011-08-09 16:12:27 -05:00
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2012-02-03 23:34:56 +08:00
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2019-05-13 17:16:09 -07:00
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2008-02-07 17:47:41 -08:00
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2008-01-07 23:20:27 -08:00
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2007-05-06 14:49:36 -07:00
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slub: add min_partial sysfs tunable
Now that a cache's min_partial has been moved to struct kmem_cache, it's
possible to easily tune it from userspace by adding a sysfs attribute.
It may not be desirable to keep a large number of partial slabs around
if a cache is used infrequently and memory, especially when constrained
by a cgroup, is scarce. It's better to allow userspace to set the
minimum policy per cache instead of relying explicitly on
kmem_cache_shrink().
The memory savings from simply moving min_partial from struct
kmem_cache_node to struct kmem_cache is obviously not significant
(unless maybe you're from SGI or something), at the largest it's
# allocated caches * (MAX_NUMNODES - 1) * sizeof(unsigned long)
The true savings occurs when userspace reduces the number of partial
slabs that would otherwise be wasted, especially on machines with a
large number of nodes (ia64 with CONFIG_NODES_SHIFT at 10 for default?).
As well as the kernel estimates ideal values for n->min_partial and
ensures it's within a sane range, userspace has no other input other
than writing to /sys/kernel/slab/cache/shrink.
There simply isn't any better heuristic to add when calculating the
partial values for a better estimate that works for all possible caches.
And since it's currently a static value, the user really has no way of
reclaiming that wasted space, which can be significant when constrained
by a cgroup (either cpusets or, later, memory controller slab limits)
without shrinking it entirely.
This also allows the user to specify that increased fragmentation and
more partial slabs are actually desired to avoid the cost of allocating
new slabs at runtime for specific caches.
There's also no reason why this should be a per-struct kmem_cache_node
value in the first place. You could argue that a machine would have
such node size asymmetries that it should be specified on a per-node
basis, but we know nobody is doing that right now since it's a purely
static value at the moment and there's no convenient way to tune that
via slub's sysfs interface.
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2009-02-22 17:40:09 -08:00
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2011-08-09 16:12:27 -05:00
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2007-05-06 14:49:36 -07:00
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2008-04-14 19:11:40 +03:00
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2007-05-06 14:49:36 -07:00
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2010-10-05 13:57:27 -05:00
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2011-08-09 16:12:27 -05:00
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2010-10-05 13:57:26 -05:00
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2010-10-05 13:57:27 -05:00
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2007-05-06 14:49:36 -07:00
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2007-05-06 14:49:43 -07:00
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2007-05-06 14:49:45 -07:00
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2010-10-05 13:57:26 -05:00
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2007-05-06 14:49:36 -07:00
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2008-01-07 23:20:26 -08:00
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2008-02-07 17:47:41 -08:00
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2011-06-01 12:25:57 -05:00
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2008-02-07 17:47:41 -08:00
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2011-06-01 12:25:58 -05:00
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2008-04-14 19:11:40 +03:00
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2011-06-01 12:25:49 -05:00
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2011-08-09 16:12:27 -05:00
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2012-02-03 23:34:56 +08:00
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2007-05-06 14:49:36 -07:00
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2010-02-26 09:36:12 +03:00
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usercopy: Prepare for usercopy whitelisting
This patch prepares the slab allocator to handle caches having annotations
(useroffset and usersize) defining usercopy regions.
This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on
my understanding of the code. Changes or omissions from the original
code are mine and don't reflect the original grsecurity/PaX code.
Currently, hardened usercopy performs dynamic bounds checking on slab
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs. To further
restrict what memory is available for copying, this creates a way to
whitelist specific areas of a given slab cache object for copying to/from
userspace, allowing much finer granularity of access control. Slab caches
that are never exposed to userspace can declare no whitelist for their
objects, thereby keeping them unavailable to userspace via dynamic copy
operations. (Note, an implicit form of whitelisting is the use of constant
sizes in usercopy operations and get_user()/put_user(); these bypass
hardened usercopy checks since these sizes cannot change at runtime.)
To support this whitelist annotation, usercopy region offset and size
members are added to struct kmem_cache. The slab allocator receives a
new function, kmem_cache_create_usercopy(), that creates a new cache
with a usercopy region defined, suitable for declaring spans of fields
within the objects that get copied to/from userspace.
In this patch, the default kmem_cache_create() marks the entire allocation
as whitelisted, leaving it semantically unchanged. Once all fine-grained
whitelists have been added (in subsequent patches), this will be changed
to a usersize of 0, making caches created with kmem_cache_create() not
copyable to/from userspace.
After the entire usercopy whitelist series is applied, less than 15%
of the slab cache memory remains exposed to potential usercopy bugs
after a fresh boot:
Total Slab Memory: 48074720
Usercopyable Memory: 6367532 13.2%
task_struct 0.2% 4480/1630720
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 269760/8740224
dentry 11.1% 585984/5273856
mm_struct 29.1% 54912/188448
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 81920/81920
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 167936/167936
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 455616/455616
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 812032/812032
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1310720/1310720
After some kernel build workloads, the percentage (mainly driven by
dentry and inode caches expanding) drops under 10%:
Total Slab Memory: 95516184
Usercopyable Memory: 8497452 8.8%
task_struct 0.2% 4000/1456000
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 1217280/39439872
dentry 11.1% 1623200/14608800
mm_struct 29.1% 73216/251264
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 94208/94208
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 245760/245760
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 563520/563520
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 794624/794624
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1257472/1257472
Signed-off-by: David Windsor <dave@nullcore.net>
[kees: adjust commit log, split out a few extra kmalloc hunks]
[kees: add field names to function declarations]
[kees: convert BUGs to WARNs and fail closed]
[kees: add attack surface reduction analysis to commit log]
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christoph Lameter <cl@linux.com>
2017-06-10 22:50:28 -04:00
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2010-02-26 09:36:12 +03:00
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2007-05-06 14:49:36 -07:00
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2017-09-06 16:21:56 -07:00
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2007-05-06 14:49:36 -07:00
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2016-01-20 15:02:32 -08:00
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|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2015-02-12 14:59:23 -08:00
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2007-05-06 14:49:36 -07:00
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slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2012-12-18 14:23:10 -08:00
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2015-02-12 14:59:23 -08:00
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slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2007-05-06 14:49:36 -07:00
|
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|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2016-01-20 15:02:32 -08:00
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|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2014-05-06 12:49:59 -07:00
|
|
|
|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
|
|
|
|
2014-05-06 12:49:59 -07:00
|
|
|
|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2015-02-12 14:59:20 -08:00
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2014-05-06 12:49:59 -07:00
|
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|
|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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|
2014-05-06 12:49:59 -07:00
|
|
|
|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2017-06-02 14:46:25 -07:00
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|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2014-05-06 12:49:59 -07:00
|
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|
|
slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2017-06-02 14:46:25 -07:00
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slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2019-05-13 17:16:09 -07:00
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slub: slub-specific propagation changes
SLUB allows us to tune a particular cache behavior with sysfs-based
tunables. When creating a new memcg cache copy, we'd like to preserve any
tunables the parent cache already had.
This can be done by tapping into the store attribute function provided by
the allocator. We of course don't need to mess with read-only fields.
Since the attributes can have multiple types and are stored internally by
sysfs, the best strategy is to issue a ->show() in the root cache, and
then ->store() in the memcg cache.
The drawback of that, is that sysfs can allocate up to a page in buffering
for show(), that we are likely not to need, but also can't guarantee. To
avoid always allocating a page for that, we can update the caches at store
time with the maximum attribute size ever stored to the root cache. We
will then get a buffer big enough to hold it. The corolary to this, is
that if no stores happened, nothing will be propagated.
It can also happen that a root cache has its tunables updated during
normal system operation. In this case, we will propagate the change to
all caches that are already active.
[akpm@linux-foundation.org: tweak code to avoid __maybe_unused]
Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-18 14:23:05 -08:00
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2014-05-06 12:50:08 -07:00
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2010-01-19 02:58:23 +01:00
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2007-05-06 14:49:36 -07:00
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2014-05-06 12:50:08 -07:00
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2007-05-06 14:49:36 -07:00
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2009-12-31 14:52:51 +01:00
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2007-05-06 14:49:36 -07:00
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2007-11-01 09:29:06 -06:00
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2007-05-06 14:49:36 -07:00
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2014-04-07 15:39:31 -07:00
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2016-01-20 15:02:32 -08:00
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2014-04-07 15:39:31 -07:00
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2015-02-12 14:59:20 -08:00
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2014-04-07 15:39:31 -07:00
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2007-05-06 14:49:36 -07:00
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2008-02-15 23:45:26 -08:00
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2007-05-06 14:49:36 -07:00
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mm: add support for kmem caches in DMA32 zone
Patch series "iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables",
v6.
This is a followup to the discussion in [1], [2].
IOMMUs using ARMv7 short-descriptor format require page tables (level 1
and 2) to be allocated within the first 4GB of RAM, even on 64-bit
systems.
For L1 tables that are bigger than a page, we can just use
__get_free_pages with GFP_DMA32 (on arm64 systems only, arm would still
use GFP_DMA).
For L2 tables that only take 1KB, it would be a waste to allocate a full
page, so we considered 3 approaches:
1. This series, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2 page
tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable to reuse
freed fragments until the whole page is freed. [3]
This series is the most memory-efficient approach.
stable@ note:
We confirmed that this is a regression, and IOMMU errors happen on 4.19
and linux-next/master on MT8173 (elm, Acer Chromebook R13). The issue
most likely starts from commit ad67f5a6545f ("arm64: replace ZONE_DMA
with ZONE_DMA32"), i.e. 4.15, and presumably breaks a number of Mediatek
platforms (and maybe others?).
[1] https://lists.linuxfoundation.org/pipermail/iommu/2018-November/030876.html
[2] https://lists.linuxfoundation.org/pipermail/iommu/2018-December/031696.html
[3] https://patchwork.codeaurora.org/patch/671639/
This patch (of 3):
IOMMUs using ARMv7 short-descriptor format require page tables to be
allocated within the first 4GB of RAM, even on 64-bit systems. On arm64,
this is done by passing GFP_DMA32 flag to memory allocation functions.
For IOMMU L2 tables that only take 1KB, it would be a waste to allocate
a full page using get_free_pages, so we considered 3 approaches:
1. This patch, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2
page tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable
to reuse freed fragments until the whole page is freed.
This change makes it possible to create a custom cache in DMA32 zone using
kmem_cache_create, then allocate memory using kmem_cache_alloc.
We do not create a DMA32 kmalloc cache array, as there are currently no
users of kmalloc(..., GFP_DMA32). These calls will continue to trigger a
warning, as we keep GFP_DMA32 in GFP_SLAB_BUG_MASK.
This implies that calls to kmem_cache_*alloc on a SLAB_CACHE_DMA32
kmem_cache must _not_ use GFP_DMA32 (it is anyway redundant and
unnecessary).
Link: http://lkml.kernel.org/r/20181210011504.122604-2-drinkcat@chromium.org
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Sasha Levin <Alexander.Levin@microsoft.com>
Cc: Huaisheng Ye <yehs1@lenovo.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Yong Wu <yong.wu@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Tomasz Figa <tfiga@google.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-28 20:43:42 -07:00
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2007-05-06 14:49:36 -07:00
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2016-03-15 14:55:06 -07:00
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2007-05-06 14:49:36 -07:00
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2016-01-14 15:18:15 -08:00
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2007-05-06 14:49:36 -07:00
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2018-04-05 16:21:20 -07:00
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2012-12-18 14:22:34 -08:00
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2007-05-06 14:49:36 -07:00
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slub: make sysfs file removal asynchronous
Commit bf5eb3de3847 ("slub: separate out sysfs_slab_release() from
sysfs_slab_remove()") made slub sysfs file removals synchronous to
kmem_cache shutdown.
Unfortunately, this created a possible ABBA deadlock between slab_mutex
and sysfs draining mechanism triggering the following lockdep warning.
======================================================
[ INFO: possible circular locking dependency detected ]
4.10.0-test+ #48 Not tainted
-------------------------------------------------------
rmmod/1211 is trying to acquire lock:
(s_active#120){++++.+}, at: [<ffffffff81308073>] kernfs_remove+0x23/0x40
but task is already holding lock:
(slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (slab_mutex){+.+.+.}:
lock_acquire+0xf6/0x1f0
__mutex_lock+0x75/0x950
mutex_lock_nested+0x1b/0x20
slab_attr_store+0x75/0xd0
sysfs_kf_write+0x45/0x60
kernfs_fop_write+0x13c/0x1c0
__vfs_write+0x28/0x120
vfs_write+0xc8/0x1e0
SyS_write+0x49/0xa0
entry_SYSCALL_64_fastpath+0x1f/0xc2
-> #0 (s_active#120){++++.+}:
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(slab_mutex);
lock(s_active#120);
lock(slab_mutex);
lock(s_active#120);
*** DEADLOCK ***
2 locks held by rmmod/1211:
#0: (cpu_hotplug.dep_map){++++++}, at: [<ffffffff810a7877>] get_online_cpus+0x37/0x80
#1: (slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
stack backtrace:
CPU: 3 PID: 1211 Comm: rmmod Not tainted 4.10.0-test+ #48
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
Call Trace:
print_circular_bug+0x1be/0x210
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
? SyS_delete_module+0x5/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
It'd be the cleanest to deal with the issue by removing sysfs files
without holding slab_mutex before the rest of shutdown; however, given
the current code structure, it is pretty difficult to do so.
This patch punts sysfs file removal to a work item. Before commit
bf5eb3de3847, the removal was punted to a RCU delayed work item which is
executed after release. Now, we're punting to a different work item on
shutdown which still maintains the goal removing the sysfs files earlier
when destroying kmem_caches.
Link: http://lkml.kernel.org/r/20170620204512.GI21326@htj.duckdns.org
Fixes: bf5eb3de3847 ("slub: separate out sysfs_slab_release() from sysfs_slab_remove()")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-23 15:08:52 -07:00
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2017-08-18 15:16:08 -07:00
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slub: make sysfs file removal asynchronous
Commit bf5eb3de3847 ("slub: separate out sysfs_slab_release() from
sysfs_slab_remove()") made slub sysfs file removals synchronous to
kmem_cache shutdown.
Unfortunately, this created a possible ABBA deadlock between slab_mutex
and sysfs draining mechanism triggering the following lockdep warning.
======================================================
[ INFO: possible circular locking dependency detected ]
4.10.0-test+ #48 Not tainted
-------------------------------------------------------
rmmod/1211 is trying to acquire lock:
(s_active#120){++++.+}, at: [<ffffffff81308073>] kernfs_remove+0x23/0x40
but task is already holding lock:
(slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (slab_mutex){+.+.+.}:
lock_acquire+0xf6/0x1f0
__mutex_lock+0x75/0x950
mutex_lock_nested+0x1b/0x20
slab_attr_store+0x75/0xd0
sysfs_kf_write+0x45/0x60
kernfs_fop_write+0x13c/0x1c0
__vfs_write+0x28/0x120
vfs_write+0xc8/0x1e0
SyS_write+0x49/0xa0
entry_SYSCALL_64_fastpath+0x1f/0xc2
-> #0 (s_active#120){++++.+}:
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(slab_mutex);
lock(s_active#120);
lock(slab_mutex);
lock(s_active#120);
*** DEADLOCK ***
2 locks held by rmmod/1211:
#0: (cpu_hotplug.dep_map){++++++}, at: [<ffffffff810a7877>] get_online_cpus+0x37/0x80
#1: (slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
stack backtrace:
CPU: 3 PID: 1211 Comm: rmmod Not tainted 4.10.0-test+ #48
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
Call Trace:
print_circular_bug+0x1be/0x210
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
? SyS_delete_module+0x5/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
It'd be the cleanest to deal with the issue by removing sysfs files
without holding slab_mutex before the rest of shutdown; however, given
the current code structure, it is pretty difficult to do so.
This patch punts sysfs file removal to a work item. Before commit
bf5eb3de3847, the removal was punted to a RCU delayed work item which is
executed after release. Now, we're punting to a different work item on
shutdown which still maintains the goal removing the sysfs files earlier
when destroying kmem_caches.
Link: http://lkml.kernel.org/r/20170620204512.GI21326@htj.duckdns.org
Fixes: bf5eb3de3847 ("slub: separate out sysfs_slab_release() from sysfs_slab_remove()")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-23 15:08:52 -07:00
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2017-08-18 15:16:08 -07:00
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slub: make sysfs file removal asynchronous
Commit bf5eb3de3847 ("slub: separate out sysfs_slab_release() from
sysfs_slab_remove()") made slub sysfs file removals synchronous to
kmem_cache shutdown.
Unfortunately, this created a possible ABBA deadlock between slab_mutex
and sysfs draining mechanism triggering the following lockdep warning.
======================================================
[ INFO: possible circular locking dependency detected ]
4.10.0-test+ #48 Not tainted
-------------------------------------------------------
rmmod/1211 is trying to acquire lock:
(s_active#120){++++.+}, at: [<ffffffff81308073>] kernfs_remove+0x23/0x40
but task is already holding lock:
(slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (slab_mutex){+.+.+.}:
lock_acquire+0xf6/0x1f0
__mutex_lock+0x75/0x950
mutex_lock_nested+0x1b/0x20
slab_attr_store+0x75/0xd0
sysfs_kf_write+0x45/0x60
kernfs_fop_write+0x13c/0x1c0
__vfs_write+0x28/0x120
vfs_write+0xc8/0x1e0
SyS_write+0x49/0xa0
entry_SYSCALL_64_fastpath+0x1f/0xc2
-> #0 (s_active#120){++++.+}:
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(slab_mutex);
lock(s_active#120);
lock(slab_mutex);
lock(s_active#120);
*** DEADLOCK ***
2 locks held by rmmod/1211:
#0: (cpu_hotplug.dep_map){++++++}, at: [<ffffffff810a7877>] get_online_cpus+0x37/0x80
#1: (slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
stack backtrace:
CPU: 3 PID: 1211 Comm: rmmod Not tainted 4.10.0-test+ #48
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
Call Trace:
print_circular_bug+0x1be/0x210
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
? SyS_delete_module+0x5/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
It'd be the cleanest to deal with the issue by removing sysfs files
without holding slab_mutex before the rest of shutdown; however, given
the current code structure, it is pretty difficult to do so.
This patch punts sysfs file removal to a work item. Before commit
bf5eb3de3847, the removal was punted to a RCU delayed work item which is
executed after release. Now, we're punting to a different work item on
shutdown which still maintains the goal removing the sysfs files earlier
when destroying kmem_caches.
Link: http://lkml.kernel.org/r/20170620204512.GI21326@htj.duckdns.org
Fixes: bf5eb3de3847 ("slub: separate out sysfs_slab_release() from sysfs_slab_remove()")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-23 15:08:52 -07:00
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2007-05-06 14:49:36 -07:00
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2017-02-22 15:41:39 -08:00
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2012-11-28 16:23:07 +00:00
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2007-05-06 14:49:36 -07:00
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slub: make sysfs file removal asynchronous
Commit bf5eb3de3847 ("slub: separate out sysfs_slab_release() from
sysfs_slab_remove()") made slub sysfs file removals synchronous to
kmem_cache shutdown.
Unfortunately, this created a possible ABBA deadlock between slab_mutex
and sysfs draining mechanism triggering the following lockdep warning.
======================================================
[ INFO: possible circular locking dependency detected ]
4.10.0-test+ #48 Not tainted
-------------------------------------------------------
rmmod/1211 is trying to acquire lock:
(s_active#120){++++.+}, at: [<ffffffff81308073>] kernfs_remove+0x23/0x40
but task is already holding lock:
(slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (slab_mutex){+.+.+.}:
lock_acquire+0xf6/0x1f0
__mutex_lock+0x75/0x950
mutex_lock_nested+0x1b/0x20
slab_attr_store+0x75/0xd0
sysfs_kf_write+0x45/0x60
kernfs_fop_write+0x13c/0x1c0
__vfs_write+0x28/0x120
vfs_write+0xc8/0x1e0
SyS_write+0x49/0xa0
entry_SYSCALL_64_fastpath+0x1f/0xc2
-> #0 (s_active#120){++++.+}:
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(slab_mutex);
lock(s_active#120);
lock(slab_mutex);
lock(s_active#120);
*** DEADLOCK ***
2 locks held by rmmod/1211:
#0: (cpu_hotplug.dep_map){++++++}, at: [<ffffffff810a7877>] get_online_cpus+0x37/0x80
#1: (slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
stack backtrace:
CPU: 3 PID: 1211 Comm: rmmod Not tainted 4.10.0-test+ #48
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
Call Trace:
print_circular_bug+0x1be/0x210
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
? SyS_delete_module+0x5/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
It'd be the cleanest to deal with the issue by removing sysfs files
without holding slab_mutex before the rest of shutdown; however, given
the current code structure, it is pretty difficult to do so.
This patch punts sysfs file removal to a work item. Before commit
bf5eb3de3847, the removal was punted to a RCU delayed work item which is
executed after release. Now, we're punting to a different work item on
shutdown which still maintains the goal removing the sysfs files earlier
when destroying kmem_caches.
Link: http://lkml.kernel.org/r/20170620204512.GI21326@htj.duckdns.org
Fixes: bf5eb3de3847 ("slub: separate out sysfs_slab_release() from sysfs_slab_remove()")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-23 15:08:52 -07:00
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2017-02-22 15:41:39 -08:00
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2017-11-15 17:32:25 -08:00
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2007-05-06 14:49:36 -07:00
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2007-11-01 09:29:06 -06:00
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2007-05-06 14:49:36 -07:00
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2017-02-22 15:41:39 -08:00
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2014-01-04 16:32:31 +09:00
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2014-04-07 15:39:32 -07:00
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2015-09-04 15:45:51 -07:00
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2007-05-06 14:49:36 -07:00
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2014-04-07 15:39:32 -07:00
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2014-04-07 15:39:31 -07:00
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2016-01-20 15:02:32 -08:00
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2017-02-22 15:41:39 -08:00
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2014-04-07 15:39:31 -07:00
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2014-04-07 15:39:32 -07:00
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2014-04-07 15:39:31 -07:00
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2007-05-06 14:49:36 -07:00
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2014-04-07 15:39:32 -07:00
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2007-05-06 14:49:36 -07:00
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2017-02-22 15:41:11 -08:00
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2007-05-06 14:49:36 -07:00
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2012-07-06 15:25:11 -05:00
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2010-07-19 11:39:11 -05:00
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|
slub: make sysfs file removal asynchronous
Commit bf5eb3de3847 ("slub: separate out sysfs_slab_release() from
sysfs_slab_remove()") made slub sysfs file removals synchronous to
kmem_cache shutdown.
Unfortunately, this created a possible ABBA deadlock between slab_mutex
and sysfs draining mechanism triggering the following lockdep warning.
======================================================
[ INFO: possible circular locking dependency detected ]
4.10.0-test+ #48 Not tainted
-------------------------------------------------------
rmmod/1211 is trying to acquire lock:
(s_active#120){++++.+}, at: [<ffffffff81308073>] kernfs_remove+0x23/0x40
but task is already holding lock:
(slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (slab_mutex){+.+.+.}:
lock_acquire+0xf6/0x1f0
__mutex_lock+0x75/0x950
mutex_lock_nested+0x1b/0x20
slab_attr_store+0x75/0xd0
sysfs_kf_write+0x45/0x60
kernfs_fop_write+0x13c/0x1c0
__vfs_write+0x28/0x120
vfs_write+0xc8/0x1e0
SyS_write+0x49/0xa0
entry_SYSCALL_64_fastpath+0x1f/0xc2
-> #0 (s_active#120){++++.+}:
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(slab_mutex);
lock(s_active#120);
lock(slab_mutex);
lock(s_active#120);
*** DEADLOCK ***
2 locks held by rmmod/1211:
#0: (cpu_hotplug.dep_map){++++++}, at: [<ffffffff810a7877>] get_online_cpus+0x37/0x80
#1: (slab_mutex){+.+.+.}, at: [<ffffffff8120f691>] kmem_cache_destroy+0x41/0x2d0
stack backtrace:
CPU: 3 PID: 1211 Comm: rmmod Not tainted 4.10.0-test+ #48
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
Call Trace:
print_circular_bug+0x1be/0x210
__lock_acquire+0x10ed/0x1260
lock_acquire+0xf6/0x1f0
__kernfs_remove+0x254/0x320
kernfs_remove+0x23/0x40
sysfs_remove_dir+0x51/0x80
kobject_del+0x18/0x50
__kmem_cache_shutdown+0x3e6/0x460
kmem_cache_destroy+0x1fb/0x2d0
kvm_exit+0x2d/0x80 [kvm]
vmx_exit+0x19/0xa1b [kvm_intel]
SyS_delete_module+0x198/0x1f0
? SyS_delete_module+0x5/0x1f0
entry_SYSCALL_64_fastpath+0x1f/0xc2
It'd be the cleanest to deal with the issue by removing sysfs files
without holding slab_mutex before the rest of shutdown; however, given
the current code structure, it is pretty difficult to do so.
This patch punts sysfs file removal to a work item. Before commit
bf5eb3de3847, the removal was punted to a RCU delayed work item which is
executed after release. Now, we're punting to a different work item on
shutdown which still maintains the goal removing the sysfs files earlier
when destroying kmem_caches.
Link: http://lkml.kernel.org/r/20170620204512.GI21326@htj.duckdns.org
Fixes: bf5eb3de3847 ("slub: separate out sysfs_slab_release() from sysfs_slab_remove()")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-06-23 15:08:52 -07:00
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2017-02-22 15:41:11 -08:00
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2018-06-27 23:26:09 -07:00
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2017-02-22 15:41:11 -08:00
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2007-05-06 14:49:36 -07:00
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2008-12-05 14:08:08 +11:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:27 -07:00
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2007-05-06 14:49:36 -07:00
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2012-07-06 15:25:11 -05:00
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2007-05-06 14:49:36 -07:00
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2007-11-01 09:29:06 -06:00
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2007-05-06 14:49:36 -07:00
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2007-07-17 04:03:19 -07:00
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2007-05-06 14:49:36 -07:00
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2012-07-06 15:25:12 -05:00
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2010-07-19 11:39:11 -05:00
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2007-11-06 10:36:58 -08:00
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2007-11-01 09:29:06 -06:00
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2012-07-06 15:25:12 -05:00
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2014-06-04 16:06:34 -07:00
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2007-05-06 14:49:36 -07:00
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2012-07-06 15:25:11 -05:00
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2007-05-09 02:32:39 -07:00
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2007-07-17 04:03:19 -07:00
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2007-05-09 02:32:39 -07:00
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2007-08-30 23:56:26 -07:00
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2014-06-04 16:06:34 -07:00
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2007-05-09 02:32:39 -07:00
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2007-05-06 14:49:36 -07:00
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2007-08-30 23:56:26 -07:00
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2014-06-04 16:06:34 -07:00
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2007-05-06 14:49:36 -07:00
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2012-07-06 15:25:12 -05:00
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2007-05-06 14:49:36 -07:00
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2010-10-05 13:57:26 -05:00
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2008-01-01 17:23:28 +01:00
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2017-11-15 17:32:03 -08:00
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2012-10-19 18:20:27 +04:00
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2008-01-01 17:23:28 +01:00
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2008-04-14 19:11:40 +03:00
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2008-01-01 17:23:28 +01:00
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2014-08-06 16:04:09 -07:00
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2008-01-01 17:23:28 +01:00
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2014-08-06 16:04:09 -07:00
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2013-07-04 08:33:26 +08:00
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2008-04-14 19:11:40 +03:00
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2008-01-01 17:23:28 +01:00
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2012-10-19 18:20:27 +04:00
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2008-01-01 17:23:28 +01:00
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2012-10-19 18:20:27 +04:00
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2008-10-06 02:42:17 +04:00
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2012-10-19 18:20:25 +04:00
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2008-10-06 02:42:17 +04:00
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2012-10-19 18:20:25 +04:00
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2008-10-06 02:42:17 +04:00
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2017-11-15 17:32:03 -08:00
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