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Date: Mon, 18 Feb 2013 09:16:47 -0800
From: Tejun Heo <tj@kernel.org>
To: Li Zefan <lizefan@huawei.com>
Cc: Cgroups <cgroups@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        "Kirill A. Shutemov" <kirill@shutemov.name>
Subject: Re: [PATCH v2] cgroup: fix cgroup_rmdir() vs close(eventfd) race
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On Mon, Feb 18, 2013 at 02:12:23PM +0800, Li Zefan wrote:
> commit 205a872bd6f9a9a09ef035ef1e90185a8245cc58 ("cgroup: fix lockdep
> warning for event_control") solved a deadlock by introducing a new
> bug.
> 
> Move cgrp->event_list to a temporary list doesn't mean you can traverse
> this list locklessly, because at the same time cgroup_event_wake() can
> be called and remove the event from the list. The result of this race
> is disastrous.
> 
> We adopt the way how kvm irqfd code implements race-free event removal,
> which is now described in the comments in cgroup_event_wake().
> 
> Signed-off-by: Li Zefan <lizefan@huawei.com>

Applied to cgroup/for-3.9.

Thanks.

-- 
tejun