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Message-ID: <6599ad830804162224s42ba221vea981fe34b30636a@mail.gmail.com>
Date: Wed, 16 Apr 2008 22:24:09 -0700
From: "Paul Menage" <menage@google.com>
To: "Andrew Morton" <akpm@linux-foundation.org>
Subject: Re: [PATCH] cgroup: fix a race condition in manipulating tsk->cg_list
Cc: "Li Zefan" <lizf@cn.fujitsu.com>,
       "Linus Torvalds" <torvalds@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>,
       "Linux Containers" <containers@lists.linux-foundation.org>,
       "Balbir Singh" <balbir@linux.vnet.ibm.com>,
       "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com>,
       "Paul Jackson" <pj@sgi.com>
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On Wed, Apr 16, 2008 at 10:16 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
>  > > Maybe it would be better to not do a cgroup_exit() until we're
>  > > unhashed, so that cgroup_enable_task_cg_list() can't find the exiting
>  > > task?
>
>  So we won't be doing what Paul suggested?
>

It's not as high a priority as Li's bug fix (which may be a good
candidate for 2.6.25.1) but for the future I think I'll implement this
distinguished css_set pointer for tasks that have finished
cgroup_exit(), since I think it will make the similar synchronization
in attach_task() cleaner, as well as cgroup_enable_task_cg_list().

Paul