On Wed, Nov 15, 2023 at 09:20:43AM -0700, Tim Van Patten wrote:
> From: Tim Van Patten <timvp@xxxxxxxxxx>
>
> __thaw_task() was recently updated to warn if the task being thawed was
> part of a freezer cgroup that is still currently freezing:
>
> void __thaw_task(struct task_struct *p)
> {
> ...
> if (WARN_ON_ONCE(freezing(p)))
> goto unlock;
>
> This has exposed a bug in cgroup1 freezing where when CGROUP_FROZEN is
> asserted, the CGROUP_FREEZING bits are not also cleared at the same
> time. Meaning, when a cgroup is marked FROZEN it continues to be marked
> FREEZING as well. This causes the WARNING to trigger, because
> cgroup_freezing() thinks the cgroup is still freezing.
>
> There are two ways to fix this:
>
> 1. Whenever FROZEN is set, clear FREEZING for the cgroup and all
> children cgroups.
> 2. Update cgroup_freezing() to also verify that FROZEN is not set.
>
> This patch implements option (2), since it's smaller and more
> straightforward.
>
> Signed-off-by: Tim Van Patten <timvp@xxxxxxxxxx>
Applied to cgroup/for-6.7-fixes.
Thanks.
--
tejun
