Re: sched: fair: NULL ptr deref in check_preempt_wakeup

[Peter Zijlstra <peterz@infradead.org>]

On Wed, Feb 19, 2014 at 01:10:22PM -0500, Sasha Levin wrote:
> On 02/17/2014 09:26 PM, Michael wang wrote:
> >On 02/17/2014 05:20 PM, Peter Zijlstra wrote:
> >[snip]
> >>>>>  static void switched_to_fair(struct rq *rq, struct task_struct *p)
> >>>>>  {
> >>>>>-	if (!p->se.on_rq)
> >>>>>+	struct sched_entity *se = &p->se;
> >>>>>+#ifdef CONFIG_FAIR_GROUP_SCHED
> >>>>>+	se->depth = se->parent ? se->parent->depth + 1 : 0;
> >>>>>+#endif
> >>>>>+	if (!se->on_rq)
> >>>>>  		return;
> >>>>>
> >>>>>  	/*
> >>>
> >>>Yes indeed. My first idea yesterday was to put it in set_task_rq() to be
> >>>absolutely sure we catch all; but if this is sufficient its better.
> >Agree, let's wait for Sasha's testing result then:)
> 
> I took my time with testing it seems I'm hitting new issues with both sched
> and mm, and I've wanted to confirm I don't see this one any more.
> 
> It does seem like this patch fixes the problem for me, so:
> 
> 	Tested-by: Sasha Levin <sasha.levin@oracle.com>
> 

Thanks!