From mboxrd@z Thu Jan 1 00:00:00 1970 From: "tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" Subject: Re: 3.5-rc3: BUG: Dentry still in use (1) [unmount of cgroup cgroup] Date: Thu, 28 Jun 2012 11:07:12 -0700 Message-ID: <20120628180712.GC22641@google.com> References: <20120627182903.GP15811@google.com> <4FEBF4B7.2070105@huawei.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=WpTIe/xK6vs53lk/C5dZgBO7HTgjlGDrgBYSFpLKzqo=; b=rzQy17Ow2Ot/Z3n8bAV+2C3afnELBMDlHm/2EmTLFwSi0thZoU/TURvRswKsc9C1Qw E4SWdd1rgjx8rVvK4G+s+38YN1+tZzusSVt1Aq1ZgoeV1sAOQBl3uQnEACv80Vy1CvLa LH4yPdpHkKuY8CSDUw2ASC0bdTsQgdlaBPz5hrFBvguW0qdfdorLWWstFlEqX/NAhOhl 9lS/U4MiaNUWISwT6LjeQVPbqz/GOXhlbYbZPaIhcxR8SUvJymTacO0iqaJTH8CZtuB5 KJK6nF3CKrwVMGvTS+nIvvFXDBjLWngkyMaXubYL89wnJ80z7XsR5vyzOvUIUTeYIccl CygQ== Content-Disposition: inline In-Reply-To: <4FEBF4B7.2070105-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Li Zefan Cc: shyju pv , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Sanil kumar , Masanari Iida 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755747Ab2F1SHT (ORCPT ); Thu, 28 Jun 2012 14:07:19 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:41666 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752289Ab2F1SHQ (ORCPT ); Thu, 28 Jun 2012 14:07:16 -0400 Date: Thu, 28 Jun 2012 11:07:12 -0700 From: "tj@kernel.org" To: Li Zefan Cc: shyju pv , "linux-kernel@vger.kernel.org" , "cgroups@vger.kernel.org" , Sanil kumar , Masanari Iida Subject: Re: 3.5-rc3: BUG: Dentry still in use (1) [unmount of cgroup cgroup] Message-ID: <20120628180712.GC22641@google.com> References: <20120627182903.GP15811@google.com> <4FEBF4B7.2070105@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FEBF4B7.2070105@huawei.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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