From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750855AbXCTNh0 (ORCPT ); Tue, 20 Mar 2007 09:37:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750797AbXCTNh0 (ORCPT ); Tue, 20 Mar 2007 09:37:26 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:42994 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750855AbXCTNhZ (ORCPT ); Tue, 20 Mar 2007 09:37:25 -0400 Subject: Re: dquot.c: possible circular locking Re: [2.6.20] BUG: workqueue leaked lock From: Arjan van de Ven To: Jan Kara Cc: Jarek Poplawski , Folkert van Heusden , Andrew Morton , linux-kernel@vger.kernel.org, Oleg Nesterov , Neil Brown , Christoph Hellwig In-Reply-To: <20070320121909.GB14319@duck.suse.cz> References: <20070315191749.GS31960@vanheusden.com> <20070320111701.GB1751@ff.dom.local> <20070320112253.GC1751@ff.dom.local> <20070320113151.GA12462@ff.dom.local> <20070320121909.GB14319@duck.suse.cz> Content-Type: text/plain Organization: Intel International BV Date: Tue, 20 Mar 2007 14:35:10 +0100 Message-Id: <1174397710.1158.75.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.8.3 (2.8.3-1.fc6) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > Yes, I was looking at it. Hmm, we can possibly get rid of tty_mutex being > acquired under dqptr_sem in quota code. But looking at the path from > con_close() there's another inversion with i_mutex which is also acquired > along the path for sysfs. And we can hardly get rid of it in the quota code. > Now none of these is a real deadlock as quota should never call > print_warning() for sysfs (it doesn't use quota) but still it's nasty. I > suppose tty_mutex is above i_mutex because of those sysfs calls and it > seems sysfs must be called under tty_mutex because of races with > init_dev(). So it's not easy to get rid of that dependency either. maybe a far more serious option: Why on EARTH is the quota code going to TTY's directly? That's just WRONG. Maybe it wasn't 10 years ago, but nowadays most people use graphical user interfaces and the like... can we please just get rid of this instead?