Re: [PATCH] cgroup: missing rcu read lock around task_css_set

From: Tejun Heo
Date: Mon Mar 03 2014 - 17:45:24 EST


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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/