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Filename Latest commit message Latest commit date
Chen Yu a611f9ffcf kthread: fix task state in kthread worker if being frozen
[ Upstream commit e16c7b07784f3fb03025939c4590b9a7c64970a7 ]

When analyzing a kernel waring message, Peter pointed out that there is a
race condition when the kworker is being frozen and falls into
try_to_freeze() with TASK_INTERRUPTIBLE, which could trigger a
might_sleep() warning in try_to_freeze().  Although the root cause is not
related to freeze()[1], it is still worthy to fix this issue ahead.

One possible race scenario:

        CPU 0                                           CPU 1
        -----                                           -----

        // kthread_worker_fn
        set_current_state(TASK_INTERRUPTIBLE);
                                                       suspend_freeze_processes()
                                                         freeze_processes
                                                           static_branch_inc(&freezer_active);
                                                         freeze_kernel_threads
                                                           pm_nosig_freezing = true;
        if (work) { //false
          __set_current_state(TASK_RUNNING);

        } else if (!freezing(current)) //false, been frozen

                      freezing():
                      if (static_branch_unlikely(&freezer_active))
                        if (pm_nosig_freezing)
                          return true;
          schedule()
	}

        // state is still TASK_INTERRUPTIBLE
        try_to_freeze()
          might_sleep() <--- warning

Fix this by explicitly set the TASK_RUNNING before entering
try_to_freeze().

Link: https://lore.kernel.org/lkml/Zs2ZoAcUsZMX2B%2FI@chenyu5-mobl2/ [1]
Link: https://lkml.kernel.org/r/20240827112308.181081-1-yu.c.chen@intel.com
Fixes: b56c0d8937 ("kthread: implement kthread_worker")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: David Gow <davidgow@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Mickaël Salaün <mic@digikod.net>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-11-08 16:20:30 +01:00
arch xen: use correct end address of kernel for conflict checking 2024-11-08 16:20:30 +01:00
block block, bfq: don't break merge chain in bfq_split_bfqq() 2024-11-08 16:20:28 +01:00
certs
crypto
Documentation ipmi: docs: don't advertise deprecated sysfs entries 2024-11-08 16:20:29 +01:00
drivers tpm: Clean up TPM space after command failure 2024-11-08 16:20:30 +01:00
fs jfs: fix out-of-bounds in dbNextAG() and diAlloc() 2024-11-08 16:20:29 +01:00
include kthread: add kthread_work tracepoints 2024-11-08 16:20:30 +01:00
init
ipc
kernel kthread: fix task state in kthread worker if being frozen 2024-11-08 16:20:30 +01:00
lib xz: cleanup CRC32 edits from 2018 2024-11-08 16:20:30 +01:00
LICENSES
mm
net net: tipc: avoid possible garbage value 2024-11-08 16:20:27 +01:00
samples
scripts scripts: kconfig: merge_config: config files: add a trailing newline 2024-11-08 16:20:24 +01:00
security smack: unix sockets: fix accept()ed socket label 2024-09-12 11:03:52 +02:00
sound ASoC: tda7419: fix module autoloading 2024-11-08 16:20:25 +01:00
tools selftests/bpf: Fix error compiling test_lru_map.c 2024-11-08 16:20:30 +01:00
usr
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.cocciconfig
.get_maintainer.ignore
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COPYING
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Kbuild
Kconfig
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Makefile Linux 5.4.284 2024-09-12 11:03:57 +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.