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