From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751408AbWFEUPu (ORCPT ); Mon, 5 Jun 2006 16:15:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751409AbWFEUPu (ORCPT ); Mon, 5 Jun 2006 16:15:50 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:14828 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1751408AbWFEUPt (ORCPT ); Mon, 5 Jun 2006 16:15:49 -0400 Date: Mon, 5 Jun 2006 22:15:10 +0200 From: Ingo Molnar To: Jan Kara Cc: Arjan van de Ven , Valdis.Kletnieks@vt.edu, linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: 2.6.17-rc5-mm3-lockdep - locking error in quotaon Message-ID: <20060605201510.GA15907@elte.hu> References: <200606051700.k55H015q004029@turing-police.cc.vt.edu> <1149528339.3111.114.camel@laptopd505.fenrus.org> <200606051920.k55JKQGx003031@turing-police.cc.vt.edu> <20060605193552.GB24342@atrey.karlin.mff.cuni.cz> <1149537156.3111.123.camel@laptopd505.fenrus.org> <20060605200652.GC24342@atrey.karlin.mff.cuni.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060605200652.GC24342@atrey.karlin.mff.cuni.cz> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -3.1 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-3.1 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.0 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5005] 0.2 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Jan Kara wrote: > > but that doesn't quite match your description... > This piece of code is there just because we avoid page cache when > doing quota writes. That is a different story and should cause problems > with your lock checker. > Standard way of running quota is: > - get i_mutex for data_inode > - write some data to data_inode > - requires allocation -> calls DQUOT_ALLOC_SPACE > - DQUOT_ALLOC_SPACE acquires some quota locks, decides it wants to > write out quota structure (e.g. because we are journaling quota and > must preserve quota integrity) > - acquires dqio_sem, calls filesystem specific quota writing > function - e.g. ext3_quota_write() > - this function acquires i_mutex for quota file > > I think this is the type of circle your checker has found. the validator noticed a circular dependency (AB->BA, or AB->BC->CA, etc.) - while the nesting above it would report as: "BUG: possible deadlock detected!". Ingo