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Date: Fri, 14 Jan 2011 13:29:34 +0800
From: Li Zefan <lizf@cn.fujitsu.com>
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To: Al Viro <viro@ZenIV.linux.org.uk>
CC: Nick Piggin <npiggin@gmail.com>, Paul Menage <menage@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        containers@lists.linux-foundation.org,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: kernel BUG at fs/dcache.c:1363 (from cgroup)
References: <4D2FD771.9040301@cn.fujitsu.com> <20110114051453.GY19804@ZenIV.linux.org.uk>
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Al Viro wrote:
> On Fri, Jan 14, 2011 at 12:56:17PM +0800, Li Zefan wrote:
>> Just mount the cgroupfs:
>>
>> # mount -t cgroup -o cpuset xxx /mnt
>> (oops!!)
>>
>> The bug is caused by:
>>
>> =========
>> commit 0df6a63f8735a7c8a877878bc215d4312e41ef81
>> Author: Al Viro <viro@zeniv.linux.org.uk>
>> Date:   Tue Dec 21 13:29:29 2010 -0500
>>
>>     switch cgroup
>>     
>>     switching it to s_d_op allows to kill the cgroup_lookup() kludge.
>>     
>>     Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
>> =========
>>
>> This line:
>>
>> +       sb->s_d_op = &cgroup_dops;
> 
> Oh, crap...  Right, it's using simple_lookup().  Let me check if anything
> else might be stepping on that.
> 
> Umm...  There's a very strange codepath in btrfs that also might.
> Interesting.  Fix for cgroup, AFAICS, should be this:
> 

patch tested. thanks!