cgroup/cpuset: Call is_in_v2_mode() after acquiring cpuset_mutex in cpuset_handle_hotplug()

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It is reported by sashiko that calling is_in_v2_mode() outside of
cpuset_mutex critical section in cpuset_handle_hotplug() can introduce
a TOCTOU race where cgroup hierarchy may have changed from v1 to v2 or
vice versa after is_in_v2_mode() is called leading to erroneously skip
the allocation of tmpmasks or incorrectly modify cpus_allowed masks,
resulting in cpuset state corruption. Fix that by calling is_in_v2_mode()
after acquiring the cpuset_mutex.

Fixes: b8d1b8ee93 ("cpuset: Allow v2 behavior in v1 cgroup")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

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Waiman Long 2026-10-05 06:43:10 -04:00 • committed by Tejun Heo

parent 23b1ab15ca

commit b8eb5fd5bd

1 changed files with 5 additions and 4 deletions

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kernel/cgroup/cpuset.c

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