From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "xiaoqiang.zhao" <zhaoxiaoqiang007@gmail.com>
Cc: linux-rt-users@vger.kernel.org
Subject: Re: schdule bug in 4.4.38-rt49
Date: Thu, 4 Jul 2019 10:00:34 +0200 [thread overview]
Message-ID: <20190704080034.i6lztjc4ocykrwpy@linutronix.de> (raw)
In-Reply-To: <987eec05-14d0-29a5-723c-7bfbc0a5465b@gmail.com>
On 2019-07-04 13:50:08 [+0800], xiaoqiang.zhao wrote:
>
> > > 2) -> __schedule_bug ( leads to kernel pagefault exception, OOPS!!)
> > >
> > > Before schedule, we have call preempt_disable twice, this will definitely
> > > bump preempt_count to 2 and
> >
> > something probably disabled preemption before that
>
> I feel this is not make sense. In my opinion, the preempt_count must be
> zero before we call 'schedule()',
that is correct. I was saying that the preempt count was > 0 before
wake_up() was invoked.
> otherwise, in_atomic_preempt_off will return true and trigger the
> __schedule_bug. If we have already
>
> disable_preempt, we may in atomic context and we should not call schedule,
> right ?
correct.
Sebastian
next prev parent reply other threads:[~2019-07-04 8:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-26 7:35 schdule bug in 4.4.38-rt49 xiaoqiang.zhao
2019-07-03 11:42 ` Sebastian Andrzej Siewior
[not found] ` <987eec05-14d0-29a5-723c-7bfbc0a5465b@gmail.com>
2019-07-04 8:00 ` Sebastian Andrzej Siewior [this message]
2019-07-04 10:17 ` xiaoqiang.zhao
2019-07-05 6:31 ` xiaoqiang.zhao
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