From: Valentin Schneider <valentin.schneider@arm.com>
To: Quentin Perret <qperret@google.com>
Cc: kernel test robot <lkp@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
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 12:37:09 +0000 [thread overview]
Message-ID: <6a23a062-9b82-668d-7945-8da34f4dc5f0@arm.com> (raw)
In-Reply-To: <20191107121551.GB82729@google.com>
On 07/11/2019 12:15, Quentin Perret wrote:
> On Thursday 07 Nov 2019 at 12:09:22 (+0000), Quentin Perret wrote:
>> sched_move_task() follows what Peter called the 'change' pattern, so I'm
>> thinking this is most likely the same issue. Dropping the lock causes an
>> unmitigated race between sched_move_task() and pick_next_task_dl(), so
>> hilarity ensues (set_next_task() being called twice for instance).
>
> Bah, scratch that. 10e7071b2 is clearly before the pick_next_task()
> rework, so that's not it :(
>
And besides we don't drop the lock until reaching pick_next_task_fair(),
and the splat says it died on pick_next_task_dl() which happens earlier.
> Quentin
>
next prev parent reply other threads:[~2019-11-07 12:37 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 [this message]
2019-11-07 12:43 ` Quentin Perret
2019-11-07 13:51 ` Valentin Schneider
2019-11-07 14:46 ` Peter Zijlstra
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