From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932081AbWFGJR2 (ORCPT ); Wed, 7 Jun 2006 05:17:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932080AbWFGJR2 (ORCPT ); Wed, 7 Jun 2006 05:17:28 -0400 Received: from hellhawk.shadowen.org ([80.68.90.175]:14609 "EHLO hellhawk.shadowen.org") by vger.kernel.org with ESMTP id S932081AbWFGJR1 (ORCPT ); Wed, 7 Jun 2006 05:17:27 -0400 Message-ID: <4486998D.6060302@shadowen.org> Date: Wed, 07 Jun 2006 10:17:01 +0100 From: Andy Whitcroft User-Agent: Debian Thunderbird 1.0.7 (X11/20051017) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Ingo Molnar CC: "Randy.Dunlap" , mbligh@google.com, akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [patch, -rc5-mm3] better lock debugging: remove mutex deadlock checking code References: <44845C27.3000006@google.com> <20060605194422.GB14709@elte.hu> <20060605130039.db1ac80c.rdunlap@xenotime.net> <20060606085623.GA2932@elte.hu> In-Reply-To: <20060606085623.GA2932@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > * Randy.Dunlap wrote: > > >>BUG: unable to handle kernel paging request at virtual address 22222232 > > > ok, this was a big thinko on my part, and it was right before our eyes. > Mutex deadlock checking relied on the 'big mutex debugging lock', but > that one is gone now - so mutex deadlock checking became racy (as your > crashes nicely pinpointed that). The races are more likely with an > increasing number of CPUs. > > so the patch below finishes the cleanup i started: it removes deadlock > checking from the mutex code and lets the lock validator do that. This > should also be (much) faster on SMP, because the lock validator is > lockless in the fastpath. (if CONFIG_DEBUG_LOCKDEP is disabled) > > Ingo > > ---------------- > Subject: better lock debugging: remove mutex deadlock checking code > From: Ingo Molnar > > with the lock validator we detect mutex deadlocks (and more), the mutex > deadlock checking code is both redundant and slower. So remove it. > > Signed-off-by: Ingo Molnar > --- Ok, this patch in combination with either fix for the swap max bug are showing passes across the board. Acked-by: Andy Whitcroft -apw