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: Wed, 3 Jul 2019 13:42:57 +0200 [thread overview]
Message-ID: <20190703114256.3b52kbrududxq7vz@linutronix.de> (raw)
In-Reply-To: <55c68f08-4160-4bee-fdc5-9fc1ea86cf57@gmail.com>
On 2019-06-26 15:35:04 [+0800], xiaoqiang.zhao wrote:
> Hi, guys:
Hi,
> I have built a kernel 4.4.38-rt49 with CONFIG_PREEMPT_RT_FULL=y , the
> kernel crash when I run the UnixBench of spawn test case.
Can you forward to something newer, 4.4.179-rt181 for instance?
> Here is the oops info:
…
> The call path is:
>
> do_fork-> copy_process -> threadgroup_change_end -> percpu_up_read(call
> preempt_disable) -> __percpu_up_read
>
> -> wake_up -> rt_spin_lock -> rt_spin_lock_slowlock -> schedule(call
> preempt_disable again) -> __schedule
>
> -> schedule_debug -> in_aotmic_preempt_off (return true, preempt_count ==
> 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.
> in_atomic_preempt_off will fail.
>
> I did not figure out: WHY we call schedule inside rt_spin_lock_slowlock
> and under what condition this call is correct ?
if the lock is acquired you schedule out and wait und it is available
again.
Sebastian
next prev parent reply other threads:[~2019-07-03 11:42 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 [this message]
[not found] ` <987eec05-14d0-29a5-723c-7bfbc0a5465b@gmail.com>
2019-07-04 8:00 ` Sebastian Andrzej Siewior
2019-07-04 10:17 ` xiaoqiang.zhao
2019-07-05 6:31 ` xiaoqiang.zhao
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