[PATCH] cgroup: missing rcu read lock around task_css_set

Tejun Heo tj at kernel.org
Mon Mar 3 22:45:05 UTC 2014


On Mon, Mar 03, 2014 at 05:43:11PM -0500, Sasha Levin wrote:
> On 03/03/2014 05:33 PM, Tejun Heo wrote:
> >On Sat, Mar 01, 2014 at 10:00:11PM -0500, Sasha Levin wrote:
> >>rcu read lock should be held when calling and working with task_css_set.
> >>
> >>This patch also fixes a related lockdep warning.
> >
> >Hmmm... PF_EXITING should be visible at that point and cset can't
> >change anymore.  We prolly need to update lockdep annotation rather
> >than adding spurious rcu locking around it.  Against which branch is
> >it?  Can you please post the lockdep warning?
> 
> I see it on -next.

I think the right thing to do is using task_css_set_check() with
PF_EXITING check and add comment explaining that cset can no longer
change.  Can you please write up a patch?

Thanks.

-- 
tejun


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