From: Tejun Heo <tj@kernel.org>
To: Laura Abbott <labbott@redhat.com>
Cc: Zefan Li <lizefan@huawei.com>,
linux-kernel@vger.kernel.org, regressions@leemhuis.info
Subject: Re: Crash in cgroup_procs_show
Date: Wed, 13 Dec 2017 13:37:56 -0800 [thread overview]
Message-ID: <20171213213756.GX3919388@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <121dc065-89ba-98ab-68ff-e86f1a636b06@redhat.com>
Hello, Laura.
On Wed, Dec 13, 2017 at 09:10:36AM -0800, Laura Abbott wrote:
> On 12/13/2017 07:29 AM, Tejun Heo wrote:
> >Hello, Laura.
> >
> >On Tue, Dec 12, 2017 at 04:38:33PM -0800, Laura Abbott wrote:
> >>Hi,
> >>
> >>Fedora got a bug report on 4.14.4 of a crash on
> >>reboot https://bugzilla.redhat.com/show_bug.cgi?id=1525279
> >>
> >> BUG: unable to handle kernel NULL pointer dereference at 0000000000000254
> >> IP: __task_pid_nr_ns+0xc7/0xf0
> >
> >Any chance you can map this back to the source line with addr2line?
> >
> >Thanks.
> >
>
> annotated with decode_stacktrace.sh
>
>
> IP: __task_pid_nr_ns (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/kernel/pid.c:506 /usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/kernel/pid.c:535)
Thank you very much for the trace. I *think* I found the place where
the css task iterator points to a task without holding its ref
allowing the task to go away before dereferenced. I'll update once I
learn more.
Thanks.
--
tejun
next prev parent reply other threads:[~2017-12-13 21:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-13 0:38 Crash in cgroup_procs_show Laura Abbott
2017-12-13 15:29 ` Tejun Heo
2017-12-13 17:10 ` Laura Abbott
2017-12-13 21:37 ` Tejun Heo [this message]
2017-12-20 15:13 ` [PATCH cgroup/for-4.15-fixes] cgroup: fix css_task_iter crash on CSS_TASK_ITER_PROC Tejun Heo
2017-12-20 16:38 ` Georgios Amanakis
2017-12-20 22:42 ` Rouven Czerwinski
2018-01-08 10:12 ` Rouven Czerwinski
2018-01-08 14:56 ` Tejun Heo
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