From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932187AbYETTZv (ORCPT ); Tue, 20 May 2008 15:25:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756736AbYETTYr (ORCPT ); Tue, 20 May 2008 15:24:47 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:47930 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763096AbYETTYk (ORCPT ); Tue, 20 May 2008 15:24:40 -0400 Date: Tue, 20 May 2008 12:23:56 -0700 From: Andrew Morton To: Matthew Wilcox Cc: hidave.darkstar@gmail.com, greg@kroah.com, kay.sievers@vrfy.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Subject: Re: [PATCH 1/3][-mm] add class_reclassify macro Message-Id: <20080520122356.63bd0000.akpm@linux-foundation.org> In-Reply-To: <20080520173640.GP2638@parisc-linux.org> References: <20080520095553.GA3201@darkstar.te-china.tietoenator.com> <20080520030232.fc91b64e.akpm@linux-foundation.org> <20080520103045.2bb0a033.akpm@linux-foundation.org> <20080520173640.GP2638@parisc-linux.org> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 20 May 2008 11:36:41 -0600 Matthew Wilcox wrote: > On Tue, May 20, 2008 at 10:30:45AM -0700, Andrew Morton wrote: > > Well what are these lockdep warnings? Normally such a warning means that > > we have a locking bug. I _assume_ that you've determined that the warnings > > are false-positives? > > Andrew, we already discussed this on the thread you started that you > then ignored ... rofl. All pertinent information should be in a patch's changelog. Then this sort of confusion will not occur. > > The warning which Mariusz Kozlowski discovered ("Subject: Re: > > 2.6.26-rc2-mm1: possible circular locking dependency detected") was > > triggered by the "class semaphore to mutex" conversion and it looks > > like a real bug to me. Would your patch prevent warnings such as that > > one from being available to us? > > The problem is that you add one type of class which then adds devices > that are of another class. This is not a bug. My proposal is to give > each sysfs class its own lock class; Dave's is to only do it for the > two classes he knows about that do this. Well that sounds reasonable. I'm not sure that we should introduce generic-looking helper infrastructure to do it, however. Anyway I'll happily sit back and let you guys and Greg sort this one out ;)