linux-kernel - Re: [PATCH cgroup/for-3.14-fixes] cgroup: update cgroup_enable_task_cg

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Message-ID: <52FEE10C.7010101@huawei.com>
Date:	Sat, 15 Feb 2014 11:37:48 +0800
From:	Li Zefan <lizefan@...wei.com>
To:	Tejun Heo <tj@...nel.org>
CC:	<cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH cgroup/for-3.14-fixes] cgroup: update cgroup_enable_task_cg_lists()
 to grab siglock

On 2014/2/14 2:29, Tejun Heo wrote:
> Currently, there's nothing preventing cgroup_enable_task_cg_lists()
> from missing set PF_EXITING and race against cgroup_exit().  Depending
> on the timing, cgroup_exit() may finish with the task still linked on
> css_set leading to list corruption.  Fix it by grabbing siglock in
> cgroup_enable_task_cg_lists() so that PF_EXITING is guaranteed to be
> visible.
> 
> This whole on-demand cg_list optimization is extremely fragile and has
> ample possibility to lead to bugs which can cause things like
> once-a-year oops during boot.  I'm wondering whether the better
> approach would be just adding "cgroup_disable=all" handling which
> disables the whole cgroup rather than tempting fate with this
> on-demand craziness.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Cc: stable@...r.kernel.org

Acked-by: Li Zefan <lizefan@...wei.com>

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