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Anton Altaparmakov e3f269ed0a x86/pm: Work around false positive kmemleak report in msr_build_context() 
Since:

  7ee18d6779 ("x86/power: Make restore_processor_context() sane")

kmemleak reports this issue:

  unreferenced object 0xf68241e0 (size 32):
    comm "swapper/0", pid 1, jiffies 4294668610 (age 68.432s)
    hex dump (first 32 bytes):
      00 cc cc cc 29 10 01 c0 00 00 00 00 00 00 00 00  ....)...........
      00 42 82 f6 cc cc cc cc cc cc cc cc cc cc cc cc  .B..............
    backtrace:
      [<461c1d50>] __kmem_cache_alloc_node+0x106/0x260
      [<ea65e13b>] __kmalloc+0x54/0x160
      [<c3858cd2>] msr_build_context.constprop.0+0x35/0x100
      [<46635aff>] pm_check_save_msr+0x63/0x80
      [<6b6bb938>] do_one_initcall+0x41/0x1f0
      [<3f3add60>] kernel_init_freeable+0x199/0x1e8
      [<3b538fde>] kernel_init+0x1a/0x110
      [<938ae2b2>] ret_from_fork+0x1c/0x28

Which is a false positive.

Reproducer:

  - Run rsync of whole kernel tree (multiple times if needed).
  - start a kmemleak scan
  - Note this is just an example: a lot of our internal tests hit these.

The root cause is similar to the fix in:

  b0b592cf08 x86/pm: Fix false positive kmemleak report in msr_build_context()

ie. the alignment within the packed struct saved_context
which has everything unaligned as there is only "u16 gs;" at start of
struct where in the past there were four u16 there thus aligning
everything afterwards.  The issue is with the fact that Kmemleak only
searches for pointers that are aligned (see how pointers are scanned in
kmemleak.c) so when the struct members are not aligned it doesn't see
them.

Testing:

We run a lot of tests with our CI, and after applying this fix we do not
see any kmemleak issues any more whilst without it we see hundreds of
the above report. From a single, simple test run consisting of 416 individual test
cases on kernel 5.10 x86 with kmemleak enabled we got 20 failures due to this,
which is quite a lot. With this fix applied we get zero kmemleak related failures.

Fixes: 7ee18d6779 ("x86/power: Make restore_processor_context() sane")
Signed-off-by: Anton Altaparmakov <anton@tuxera.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: stable@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240314142656.17699-1-anton@tuxera.com
2024-03-22 11:01:31 +01:00
arch x86/pm: Work around false positive kmemleak report in msr_build_context() 2024-03-22 11:01:31 +01:00
block block: fix mismatched kerneldoc function name 2024-03-14 09:40:47 -06:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This update includes the following changes: 2024-03-15 14:46:54 -07:00
Documentation I3C for 6.9 2024-03-17 16:59:33 -07:00
drivers A RISC-V irqchip driver fix. 2024-03-18 09:10:44 -07:00
fs NFS client updates for Linux 6.9 2024-03-16 11:44:00 -07:00
include Input updates for v6.9-rc0 2024-03-17 11:50:54 -07:00
init - Kuan-Wei Chiu has developed the well-named series "lib min_heap: Min 2024-03-14 18:03:09 -07:00
io_uring for-6.9/io_uring-20240310 2024-03-11 11:35:31 -07:00
ipc sysctl: allow to change limits for posix messages queues 2024-02-22 15:38:52 -08:00
kernel Fix timer migration bug that can result in long bootup 2024-03-17 12:19:02 -07:00
lib cxl for v6.9 2024-03-16 10:04:12 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm bcachefs updates for 6.9 2024-03-15 09:00:09 -07:00
net NFS client updates for Linux 6.9 2024-03-16 11:44:00 -07:00
rust arm64 updates for 6.9: 2024-03-14 15:35:42 -07:00
samples VFIO updates for v6.9-rc1 2024-03-15 13:21:13 -07:00
scripts S390: 2024-03-15 13:03:13 -07:00
security - Kuan-Wei Chiu has developed the well-named series "lib min_heap: Min 2024-03-14 18:03:09 -07:00
sound sound fixes for 6.9-rc1 2024-03-18 09:05:37 -07:00
tools powerpc updates for 6.9 2024-03-15 17:53:48 -07:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM Xen and pfncache changes for 6.9: 2024-03-11 10:42:55 -04:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap Networking changes for 6.9. 2024-03-12 17:44:08 -07:00
.rustfmt.toml
COPYING
CREDITS Not a ton of stuff happening in the clk framework in this pull request. We got 2024-03-15 11:48:01 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS phy-for-6.9 2024-03-16 11:24:51 -07:00
Makefile - Kuan-Wei Chiu has developed the well-named series "lib min_heap: Min 2024-03-14 18:03:09 -07:00
README README: Fix spelling/capitalization 2024-02-12 16:42:13 -07:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the ReStructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.