From: Peter Zijlstra <peterz@infradead.org>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Quentin Perret <qperret@google.com>,
linux-kernel@vger.kernel.org, aaron.lwe@gmail.com,
valentin.schneider@arm.com, mingo@kernel.org, pauld@redhat.com,
jdesfossez@digitalocean.com, naravamudan@digitalocean.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
juri.lelli@redhat.com, rostedt@goodmis.org, bsegall@google.com,
mgorman@suse.de, kernel-team@android.com, john.stultz@linaro.org
Subject: Re: NULL pointer dereference in pick_next_task_fair
Date: Thu, 7 Nov 2019 16:42:39 +0100 [thread overview]
Message-ID: <20191107154239.GE4114@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <79ecf426-8728-f36b-57ad-5948e5633ffb@virtuozzo.com>
On Thu, Nov 07, 2019 at 06:12:07PM +0300, Kirill Tkhai wrote:
> On 07.11.2019 16:26, Peter Zijlstra wrote:
> > Urgh... throttling.
> One more thing about current code in git. After rq->lock became able to
> be unlocked after put_prev_task() is commited, we got a new corner case.
> We usually had the same order for running task:
>
> dequeue_task()
> put_prev_task()
>
> Now the order may be reversed (this is also in case of throttling):
>
> put_prev_task() (called from pick_next_task())
> dequeue_task() (called from another cpu)
>
> This is more theoretically, since I don't see a problem here. But there are
> too many statistics and counters in sched_class methods, that it is impossible
> to be sure all of them work as expected.
Hmm,.. where does throttling happen on a remote CPU? I through both
cfs-bandwidth and dl throttle locally.
Or are you talking about NO_HZ_FULL's sched_remote_tick() ?
next prev parent reply other threads:[~2019-11-07 15:42 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-28 17:46 NULL pointer dereference in pick_next_task_fair Quentin Perret
2019-10-28 21:49 ` Peter Zijlstra
2019-10-29 11:34 ` Peter Zijlstra
2019-10-29 11:50 ` Quentin Perret
2019-10-30 22:50 ` Ram Muthiah
2019-10-31 1:33 ` Valentin Schneider
2019-10-31 10:54 ` Valentin Schneider
2019-10-31 14:24 ` Valentin Schneider
2019-10-31 22:15 ` Valentin Schneider
2019-11-06 12:05 ` Peter Zijlstra
2019-11-06 13:08 ` Peter Zijlstra
2019-11-06 15:04 ` Qais Yousef
2019-11-06 16:57 ` Peter Zijlstra
2019-11-06 17:26 ` Qais Yousef
2019-11-06 15:51 ` Kirill Tkhai
2019-11-06 16:54 ` Peter Zijlstra
2019-11-06 17:27 ` Peter Zijlstra
2019-11-07 8:36 ` Kirill Tkhai
2019-11-07 13:26 ` Peter Zijlstra
2019-11-07 15:12 ` Kirill Tkhai
2019-11-07 15:42 ` Peter Zijlstra [this message]
2019-11-07 15:53 ` Kirill Tkhai
2019-11-07 15:38 ` Quentin Perret
2019-11-07 18:43 ` Peter Zijlstra
2019-11-07 19:27 ` Quentin Perret
2019-11-07 19:31 ` Peter Zijlstra
2019-11-07 19:42 ` Quentin Perret
2019-11-07 19:29 ` Peter Zijlstra
2019-11-08 11:02 ` Quentin Perret
2019-11-08 11:47 ` Valentin Schneider
2019-11-08 11:58 ` Quentin Perret
2019-11-08 12:00 ` Peter Zijlstra
2019-11-08 12:15 ` Quentin Perret
2019-11-08 12:35 ` Peter Zijlstra
2019-11-08 12:24 ` Peter Zijlstra
2019-11-08 11:55 ` Peter Zijlstra
2019-11-08 12:52 ` Peter Zijlstra
2019-11-07 16:09 ` Qais Yousef
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