Re: [PATCH] sched, cgroup: Use exit hook to avoid use-after-freecrash

[Mike Galbraith]

On Fri, 2010-12-24 at 18:07 +0100, Peter Zijlstra wrote:
> On Fri, 2010-12-24 at 17:48 +0100, Mike Galbraith wrote:
> > On Fri, 2010-12-24 at 16:59 +0100, Peter Zijlstra wrote:
> > 
> > > So cgroup moves a task without calling cgroup_subsys::attach() which is
> > > odd, but it does have an ::exit method, sadly it calls that _before_
> > > re-assigning the task, which means we have to jump through some hoops.
> > 
> > Could you do the move in cgroup_exit() in the CONFIG_PREEMPT case?
> 
> I'm not really comfortable relying on that.. voluntary might just grow a
> cond_resched() somewhere in the exit path and lead us down the same
> path, also I think that !preempt smp might have the same race.

Yeah, good point.

	-Mike


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