Re: [PATCH] cgroup: Protect css->cgroup write under css_set_lock

[Tejun Heo]

On Wed, Jul 03, 2024 at 02:52:29PM -0400, Waiman Long wrote:
> The writing of css->cgroup associated with the cgroup root in
> rebind_subsystems() is currently protected only by cgroup_mutex.
> However, the reading of css->cgroup in both proc_cpuset_show() and
> proc_cgroup_show() is protected just by css_set_lock. That makes the
> readers susceptible to racing problems like data tearing or caching.
> It is also a problem that can be reported by KCSAN.
> 
> This can be fixed by using READ_ONCE() and WRITE_ONCE() to access
> css->cgroup. Alternatively, the writing of css->cgroup can be moved
> under css_set_lock as well which is done by this patch.
> 
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>

Applied to cgroup/for-6.10-fixes.

Thanks.

-- 
tejun