From: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH cgroup/for-3.14-fixes] cgroup: update cgroup_enable_task_cg_lists() to grab siglock
Date: Sat, 15 Feb 2014 11:37:48 +0800 [thread overview]
Message-ID: <52FEE10C.7010101@huawei.com> (raw)
In-Reply-To: <20140213182931.GB17608-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
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-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Acked-by: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
WARNING: multiple messages have this Message-ID (diff)
From: Li Zefan <lizefan@huawei.com>
To: Tejun Heo <tj@kernel.org>
Cc: <cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH cgroup/for-3.14-fixes] cgroup: update cgroup_enable_task_cg_lists() to grab siglock
Date: Sat, 15 Feb 2014 11:37:48 +0800 [thread overview]
Message-ID: <52FEE10C.7010101@huawei.com> (raw)
In-Reply-To: <20140213182931.GB17608@htj.dyndns.org>
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@kernel.org>
> Cc: stable@vger.kernel.org
Acked-by: Li Zefan <lizefan@huawei.com>
next prev parent reply other threads:[~2014-02-15 3:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-13 18:29 [PATCH cgroup/for-3.14-fixes] cgroup: update cgroup_enable_task_cg_lists() to grab siglock Tejun Heo
2014-02-13 18:29 ` Tejun Heo
[not found] ` <20140213182931.GB17608-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
2014-02-14 3:49 ` Li Zefan
2014-02-14 3:49 ` Li Zefan
2014-02-14 16:50 ` Tejun Heo
2014-02-14 20:47 ` [PATCH v2 cgroup/for-3.15] cgroup: make " Tejun Heo
2014-02-14 20:47 ` Tejun Heo
[not found] ` <20140214204709.GB2851-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2014-02-15 2:11 ` Li Zefan
2014-02-15 2:11 ` Li Zefan
2014-02-15 3:37 ` Li Zefan [this message]
2014-02-15 3:37 ` [PATCH cgroup/for-3.14-fixes] cgroup: update " Li Zefan
2014-02-18 23:25 ` Tejun Heo
2014-02-18 23:25 ` Tejun Heo
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