From: Peter Zijlstra <peterz@infradead.org>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: kernel test robot <lkp@intel.com>, Aaron Lu <aaron.lwe@gmail.com>,
Phil Auld <pauld@redhat.com>,
Julien Desfossez <jdesfossez@digitalocean.com>,
Nishanth Aravamudan <naravamudan@digitalocean.com>,
LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
lkp@01.org
Subject: Re: [sched] 10e7071b2f: BUG:kernel_NULL_pointer_dereference,address
Date: Thu, 7 Nov 2019 15:46:39 +0100 [thread overview]
Message-ID: <20191107144639.GB4114@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <d94e549d-04de-5b23-c4e0-6c161ec8213e@arm.com>
On Thu, Nov 07, 2019 at 01:51:47PM +0000, Valentin Schneider wrote:
> Using that, the fail is on:
>
> if (need_pull_dl_task(rq, prev)) {
>
> Which is most likely explained by the above call ending up doing a
>
> dl_prio(prev->prio);
>
> which doesn't play well with
>
> class->pick_next_task(rq, NULL, NULL);
>
>
> Now, this is no longer an issue (I think) with the rest of Peter's series,
> since the above deref is gone with
>
> 67692435c411 ("sched: Rework pick_next_task() slow-path")
>
> It would be interesting to know whether LKP found this on a mainline kernel
> and bisected it down, or if it stumbled on this while bisecting something
> else.
That seems pausible indeed.
prev parent reply other threads:[~2019-11-07 14:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-07 9:08 [sched] 10e7071b2f: BUG:kernel_NULL_pointer_dereference,address kernel test robot
2019-11-07 11:41 ` Valentin Schneider
2019-11-07 12:09 ` Quentin Perret
2019-11-07 12:15 ` Quentin Perret
2019-11-07 12:37 ` Valentin Schneider
2019-11-07 12:43 ` Quentin Perret
2019-11-07 13:51 ` Valentin Schneider
2019-11-07 14:46 ` Peter Zijlstra [this message]
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