From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] sched/fair: do not announce throttled next buddy in dequeue_task_fair
Date: Mon, 11 Jul 2016 11:15:40 +0300 [thread overview]
Message-ID: <578355AC.2090507@yandex-team.ru> (raw)
In-Reply-To: <CANRm+Cxo1q-GyWcSQfZ3S=FAL8opCi0uH=NVJcEFiLyf8dCbVQ@mail.gmail.com>
On 11.07.2016 10:25, Wanpeng Li wrote:
> 2016-06-16 20:57 GMT+08:00 Konstantin Khlebnikov <khlebnikov@yandex-team.ru>:
>> Hierarchy could be already throttled at this point. Throttled next
>> buddy could trigger null pointer dereference in pick_next_task_fair().
>
> There is cfs_rq->next check in pick_next_entity(), so how can null
> pointer dereference happen?
>
If we nominate task from throttled hiearchy as a next buddy then at some
level in pick_next_task_fair we could pick cfs_rq which has no runnable
entities - in pick_next_entiry both "curr" and "left" are NULL.
--
Konstantin
next prev parent reply other threads:[~2016-07-11 8:16 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-16 12:57 [PATCH] sched/fair: do not announce throttled next buddy in dequeue_task_fair Konstantin Khlebnikov
2016-06-16 17:06 ` bsegall
2016-06-21 13:44 ` Konstantin Khlebnikov
2016-06-24 9:00 ` [tip:sched/urgent] sched/fair: Do not announce throttled next buddy in dequeue_task_fair() tip-bot for Konstantin Khlebnikov
2016-07-11 7:25 ` [PATCH] sched/fair: do not announce throttled next buddy in dequeue_task_fair Wanpeng Li
2016-07-11 8:15 ` Konstantin Khlebnikov [this message]
2016-07-11 8:22 ` Xunlei Pang
2016-07-11 8:42 ` Xunlei Pang
2016-07-11 9:54 ` Wanpeng Li
2016-07-11 12:12 ` Xunlei Pang
2016-07-11 12:26 ` Konstantin Khlebnikov
2016-07-12 17:25 ` bsegall
2016-07-13 1:50 ` Wanpeng Li
2016-07-13 1:58 ` Xunlei Pang
2016-07-13 2:14 ` Wanpeng Li
2016-07-13 17:06 ` bsegall
2016-07-14 12:11 ` Wanpeng Li
2016-07-14 17:54 ` bsegall
2016-07-14 22:30 ` Wanpeng Li
2016-07-14 22:49 ` bsegall
2016-07-14 23:03 ` Wanpeng Li
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