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From: "tj@kernel.org" <tj@kernel.org>
To: Li Zefan <lizefan@huawei.com>
Cc: shyju pv <shyju.pv@huawei.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
	Sanil kumar <sanil.kumar@huawei.com>,
	Masanari Iida <standby24x7@gmail.com>
Subject: Re: 3.5-rc3: BUG: Dentry still in use (1) [unmount of cgroup cgroup]
Date: Thu, 28 Jun 2012 11:07:12 -0700	[thread overview]
Message-ID: <20120628180712.GC22641@google.com> (raw)
In-Reply-To: <4FEBF4B7.2070105@huawei.com>

Hello, Li.

On Thu, Jun 28, 2012 at 02:07:51PM +0800, Li Zefan wrote:
> > Hmm... fa980ca87d "cgroup: superblock can't be released with active
> > dentries" is supposed to have fixed that.  Looking into it.
> > 
> 
> 
> I think I know what happened here:
> 
> umount
>   deativate_super(sb)
>                        dput(subdir)
>                          subdir->d_count--
>                          d_release(subdir)
>                            deactivate_super(sb)
>                              shrink_dcache_for_umount(sb)
>                                BUG(root->d_count)!!
>                          root->d_count--

Can you please elaborate a bit?  I'm not really following?  Where does
the last root->d_count-- come from?

> I use this script to reproduce the bug:
> 
> mount -t cgroup -o cpu xxx /mnt
> mkdir /mnt/sub
> sleep 100 < /mnt/sub &
> kill $!
> wait $!
> rmdir /mnt/sub
> umount /mnt

Unfortunately, this doesn't reproduce the bug here either. :(

Thanks.

-- 
tejun

  reply	other threads:[~2012-06-28 18:07 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-24 19:08 3.5-rc3: BUG: Dentry still in use (1) [unmount of cgroup cgroup] shyju pv
2012-06-26 23:00 ` Masanari Iida
2012-06-27 18:29 ` tj
2012-06-27 23:02   ` tj
2012-06-28 14:09     ` Masanari Iida
2012-06-28  6:07   ` Li Zefan
2012-06-28  6:07   ` Li Zefan
2012-06-28 18:07     ` tj [this message]
2012-06-29  2:20       ` Li Zefan
2012-06-29 16:58         ` tj
2012-06-29 18:07           ` Masanari Iida
2012-06-30  6:13           ` Li Zefan
2012-06-30  6:47             ` Al Viro
2012-06-30  7:04               ` Tejun Heo
2012-06-30  8:34                 ` Al Viro
2012-07-03 17:10                   ` Tejun Heo
2012-07-03 17:38                     ` [PATCH] cgroup: cgroup_rm_files() was calling simple_unlink() with the wrong inode Tejun Heo
2012-07-04  5:40                       ` Li Zefan
2012-07-09 17:11                         ` Tejun Heo

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