From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764700AbXIXQ7a (ORCPT ); Mon, 24 Sep 2007 12:59:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757561AbXIXQ7K (ORCPT ); Mon, 24 Sep 2007 12:59:10 -0400 Received: from tomts16-srv.bellnexxia.net ([209.226.175.4]:52648 "EHLO tomts16-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762170AbXIXQ7I (ORCPT ); Mon, 24 Sep 2007 12:59:08 -0400 Date: Mon, 24 Sep 2007 12:59:03 -0400 From: Mathieu Desnoyers To: Peter Zijlstra Cc: Ingo Molnar , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Dave Hansen , Alexey Dobriyan Subject: Re: MAX_LOCKDEP_SUBCLASSES too low in 2.6.23-rc7-mm1 Message-ID: <20070924165903.GA24220@Krystal> References: <20070924160358.GA19736@Krystal> <20070924183759.085d901c@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20070924183759.085d901c@twins> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 12:57:00 up 56 days, 17:15, 4 users, load average: 7.62, 3.93, 1.98 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Peter Zijlstra (peterz@infradead.org) wrote: > On Mon, 24 Sep 2007 12:03:58 -0400 Mathieu Desnoyers > wrote: > > > Hi Ingo, > > > > I got the following printk when booting 2.6.23-rc7-mm1 : > > > > BUG: MAX_LOCKDEP_SUBCLASSES too low! > > turning off the locking correctness validator. > > > > Is it known/correct situation ? > > Known, bug in r/o mounts code: > > > static void lock_and_coalesce_cpu_mnt_writer_counts(void) > > { > > int cpu; > > struct mnt_writer *cpu_writer; > > > > for_each_possible_cpu(cpu) { > > cpu_writer = &per_cpu(mnt_writers, cpu); > > spin_lock_nested(&cpu_writer->lock, 42); > > ^^^^ > > How could the Ultimate Answer be wrong ? ;) Cheers, Mathieu > > What the heck is going on? Given that MAX_LOCKDEP_SUBCLASSES is only 8, > > this reliably turns off lockdep at boot. -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68