Re: 3.10.16 cgroup css_set_lock deadlock

From: Tejun Heo
Date: Fri Nov 15 2013 - 03:19:44 EST


On Thu, Nov 14, 2013 at 05:25:29PM -0600, Shawn Bohrer wrote:
> In trying to reproduce the cgroup_mutex deadlock I reported earlier
> in https://lkml.org/lkml/2013/11/11/574 I believe I encountered a
> different issue that I'm also unable to understand. This machine
> started out reporting some soft lockups that look to me like they are
> on a read_lock(css_set_lock):
>
...
> RIP: 0010:[<ffffffff8109253c>] [<ffffffff8109253c>] cgroup_attach_task+0xdc/0x7a0
...
> [<ffffffff81092e87>] attach_task_by_pid+0x167/0x1a0
> [<ffffffff81092ef3>] cgroup_tasks_write+0x13/0x20

Most likely the bug fixed by ea84753c98a7 ("cgroup: fix to break the
while loop in cgroup_attach_task() correctly"). 3.10.19 contains the
backported fix.

Thanks.

--
tejun
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