From: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Sasha Levin <sasha.levin-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] cgroup: missing rcu read lock around task_css_set
Date: Wed, 5 Mar 2014 08:57:06 +0800 [thread overview]
Message-ID: <53167662.5000801@huawei.com> (raw)
In-Reply-To: <20140304194741.GA2204-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
On 2014/3/5 3:47, Tejun Heo wrote:
> On Tue, Mar 04, 2014 at 12:20:45PM -0500, Sasha Levin wrote:
>>> Hrm... there is a PF_EXITING check there already:
>>>
>>> #define task_css_set_check(task, __c) \
>>> rcu_dereference_check((task)->cgroups, \
>>> lockdep_is_held(&cgroup_mutex) || \
>>> lockdep_is_held(&css_set_rwsem) || \
>>> ((task)->flags & PF_EXITING) || (__c))
>>>
>>> I see it's not happening on Linus's master so I'll run a bisection to figure out what broke it.
>>
>> Hi Tejun,
>>
>> It bisects down to your patch: "cgroup: drop task_lock() protection
>> around task->cgroups". I'll look into it later unless it's obvious
>> to you.
>
> Hmmm... maybe I'm confused and PF_EXITING is not set there and
> task_lock was what held off the lockdep warning. Confused....
>
Because this cgroup_exit() is called in a failure path in copy_process().
WARNING: multiple messages have this Message-ID (diff)
From: Li Zefan <lizefan@huawei.com>
To: Tejun Heo <tj@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>,
<containers@lists.linux-foundation.org>,
<cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cgroup: missing rcu read lock around task_css_set
Date: Wed, 5 Mar 2014 08:57:06 +0800 [thread overview]
Message-ID: <53167662.5000801@huawei.com> (raw)
In-Reply-To: <20140304194741.GA2204@htj.dyndns.org>
On 2014/3/5 3:47, Tejun Heo wrote:
> On Tue, Mar 04, 2014 at 12:20:45PM -0500, Sasha Levin wrote:
>>> Hrm... there is a PF_EXITING check there already:
>>>
>>> #define task_css_set_check(task, __c) \
>>> rcu_dereference_check((task)->cgroups, \
>>> lockdep_is_held(&cgroup_mutex) || \
>>> lockdep_is_held(&css_set_rwsem) || \
>>> ((task)->flags & PF_EXITING) || (__c))
>>>
>>> I see it's not happening on Linus's master so I'll run a bisection to figure out what broke it.
>>
>> Hi Tejun,
>>
>> It bisects down to your patch: "cgroup: drop task_lock() protection
>> around task->cgroups". I'll look into it later unless it's obvious
>> to you.
>
> Hmmm... maybe I'm confused and PF_EXITING is not set there and
> task_lock was what held off the lockdep warning. Confused....
>
Because this cgroup_exit() is called in a failure path in copy_process().
next prev parent reply other threads:[~2014-03-05 0:57 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-02 3:00 [PATCH] cgroup: missing rcu read lock around task_css_set Sasha Levin
2014-03-02 3:00 ` Sasha Levin
[not found] ` <1393729211-937-1-git-send-email-sasha.levin-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2014-03-03 22:33 ` Tejun Heo
2014-03-03 22:33 ` Tejun Heo
[not found] ` <20140303223327.GB26523-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2014-03-03 22:43 ` Sasha Levin
2014-03-03 22:43 ` Sasha Levin
[not found] ` <5315057F.3030602-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2014-03-03 22:45 ` Tejun Heo
2014-03-03 22:45 ` Tejun Heo
2014-03-03 22:48 ` Sasha Levin
[not found] ` <20140303224505.GE26523-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2014-03-03 22:48 ` Sasha Levin
2014-03-03 23:00 ` Sasha Levin
2014-03-03 23:00 ` Sasha Levin
[not found] ` <53150989.70307-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2014-03-04 17:20 ` Sasha Levin
2014-03-04 17:20 ` Sasha Levin
[not found] ` <53160B6D.8020501-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2014-03-04 19:47 ` Tejun Heo
2014-03-04 19:47 ` Tejun Heo
2014-03-04 19:47 ` Tejun Heo
[not found] ` <20140304194741.GA2204-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org>
2014-03-05 0:57 ` Li Zefan [this message]
2014-03-05 0:57 ` Li Zefan
[not found] ` <53167662.5000801-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2014-03-27 15:35 ` Sasha Levin
2014-03-27 15:35 ` Sasha Levin
[not found] ` <5334452D.4080200-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2014-03-28 2:48 ` Li Zefan
2014-03-28 2:48 ` Li Zefan
2014-03-03 22:43 ` Sasha Levin
-- strict thread matches above, loose matches on Subject: below --
2014-03-02 3:00 Sasha Levin
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