From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: 3.5-rc3: BUG: Dentry still in use (1) [unmount of cgroup cgroup] Date: Sat, 30 Jun 2012 07:47:24 +0100 Message-ID: <20120630064724.GC14083@ZenIV.linux.org.uk> References: <20120627182903.GP15811@google.com> <4FEBF4B7.2070105@huawei.com> <20120628180712.GC22641@google.com> <4FED10DB.7040500@huawei.com> <20120629165809.GB21048@google.com> <4FEE98EE.1050409@huawei.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <4FEE98EE.1050409-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: "tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , shyju pv , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Sanil kumar , Masanari Iida On Sat, Jun 30, 2012 at 02:13:02PM +0800, Li Zefan wrote: > dput will drop both the subdir and the root's dentry refcnt, but kill_sb will be called > inbetween. ????!!!!??!?!? > So it's bad to have dentry refcnts dangling after umount. No shit. Yes, it is bad. What on the Earth is cgroup code doing with those? And what could it possibly want to do with dentry reference after the filesystem has been shut down, assuming it could hold one in the first place? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752519Ab2F3Grf (ORCPT ); Sat, 30 Jun 2012 02:47:35 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:55145 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751193Ab2F3Grd (ORCPT ); Sat, 30 Jun 2012 02:47:33 -0400 Date: Sat, 30 Jun 2012 07:47:24 +0100 From: Al Viro To: Li Zefan Cc: "tj@kernel.org" , 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: <20120630064724.GC14083@ZenIV.linux.org.uk> References: <20120627182903.GP15811@google.com> <4FEBF4B7.2070105@huawei.com> <20120628180712.GC22641@google.com> <4FED10DB.7040500@huawei.com> <20120629165809.GB21048@google.com> <4FEE98EE.1050409@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FEE98EE.1050409@huawei.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 30, 2012 at 02:13:02PM +0800, Li Zefan wrote: > dput will drop both the subdir and the root's dentry refcnt, but kill_sb will be called > inbetween. ????!!!!??!?!? > So it's bad to have dentry refcnts dangling after umount. No shit. Yes, it is bad. What on the Earth is cgroup code doing with those? And what could it possibly want to do with dentry reference after the filesystem has been shut down, assuming it could hold one in the first place?