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Filename Latest commit message Latest commit date
Waiman Long 9f1f4e9503 mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup()
commit d1534ae23c2b6be350c8ab060803fbf6e9682adc upstream.

A soft lockup warning was observed on a relative small system x86-64
system with 16 GB of memory when running a debug kernel with kmemleak
enabled.

  watchdog: BUG: soft lockup - CPU#8 stuck for 33s! [kworker/8:1:134]

The test system was running a workload with hot unplug happening in
parallel.  Then kemleak decided to disable itself due to its inability to
allocate more kmemleak objects.  The debug kernel has its
CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE set to 40,000.

The soft lockup happened in kmemleak_do_cleanup() when the existing
kmemleak objects were being removed and deleted one-by-one in a loop via a
workqueue.  In this particular case, there are at least 40,000 objects
that need to be processed and given the slowness of a debug kernel and the
fact that a raw_spinlock has to be acquired and released in
__delete_object(), it could take a while to properly handle all these
objects.

As kmemleak has been disabled in this case, the object removal and
deletion process can be further optimized as locking isn't really needed.
However, it is probably not worth the effort to optimize for such an edge
case that should rarely happen.  So the simple solution is to call
cond_resched() at periodic interval in the iteration loop to avoid soft
lockup.

Link: https://lkml.kernel.org/r/20250728190248.605750-1-longman@redhat.com
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-08-28 16:21:30 +02:00
arch parisc: Makefile: fix a typo in palo.conf 2025-08-28 16:21:30 +02:00
block
certs
crypto crypto: algif_hash - fix double free in hash_accept 2025-06-04 14:32:35 +02:00
Documentation Documentation: ACPI: Fix parent device references 2025-08-28 16:21:23 +02:00
drivers thunderbolt: Fix copy+paste error in match_service_id() 2025-08-28 16:21:30 +02:00
fs btrfs: fix log tree replay failure due to file with 0 links and extents 2025-08-28 16:21:30 +02:00
include uapi: in6: restore visibility of most IPv6 socket options 2025-08-28 16:21:27 +02:00
init bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17 18:24:51 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:02:52 +01:00
kernel rcu: Protect ->defer_qs_iw_pending from data race 2025-08-28 16:21:26 +02:00
lib lib: test_objagg: Set error message in check_expect_hints_stats() 2025-07-17 18:24:56 +02:00
LICENSES
mm mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup() 2025-08-28 16:21:30 +02:00
net net: ncsi: Fix buffer overflow in fetching version id 2025-08-28 16:21:27 +02:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:21:19 +02:00
scripts kconfig: lxdialog: fix 'space' to (de)select options 2025-08-28 16:21:29 +02:00
security securityfs: don't pin dentries twice, once is enough... 2025-08-28 16:21:24 +02:00
sound ASoC: codecs: rt5640: Retry DEVICE_ID verification 2025-08-28 16:21:26 +02:00
tools ktest.pl: Prevent recursion of default variable options 2025-08-28 16:21:26 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-07-17 18:24:51 +02:00
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS platform: Add Surface platform directory 2025-06-27 11:02:56 +01:00
Makefile Linux 5.4.296 2025-07-17 18:25:06 +02:00
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.