From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750718AbWGQJ0f (ORCPT ); Mon, 17 Jul 2006 05:26:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750705AbWGQJ0f (ORCPT ); Mon, 17 Jul 2006 05:26:35 -0400 Received: from [216.208.38.107] ([216.208.38.107]:31104 "EHLO OTTLS.pngxnet.com") by vger.kernel.org with ESMTP id S1750718AbWGQJ0f (ORCPT ); Mon, 17 Jul 2006 05:26:35 -0400 Subject: Re: lockdep warning when nesting dm devices From: Arjan van de Ven To: Alasdair G Kergon Cc: Peter Osterlund , linux-kernel@vger.kernel.org, dm-devel@redhat.com, Ingo Molnar , Milan Broz , "Jun'ichi Nomura" In-Reply-To: <20060717024519.GA26318@agk.surrey.redhat.com> References: <20060717024519.GA26318@agk.surrey.redhat.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Mon, 17 Jul 2006 11:16:28 +0200 Message-Id: <1153127808.3062.0.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2006-07-17 at 03:45 +0100, Alasdair G Kergon wrote: > On Sat, Jul 15, 2006 at 01:17:29PM +0200, Peter Osterlund wrote: > > # echo "0 10000 linear /dev/loop0 0" | /sbin/dmsetup create test > > # echo "0 10000 linear /dev/mapper/test 0" | /sbin/dmsetup create test2 > > > I get the following warning from the lockdep validator. > > ============================================= > > [ INFO: possible recursive locking detected ] > > --------------------------------------------- > > Well at first sight the message is simply pointing out something expected - it > only say "INFO" after all - viz. recursive use of > down_read(&md->io_lock); is this indeed the same io_lock? Because if it is it's a serious deadlock; rwsem's are NOT self-recursive!