From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261711AbVGKN6D (ORCPT ); Mon, 11 Jul 2005 09:58:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261703AbVGKN56 (ORCPT ); Mon, 11 Jul 2005 09:57:58 -0400 Received: from mail.metronet.co.uk ([213.162.97.75]:48328 "EHLO mail.metronet.co.uk") by vger.kernel.org with ESMTP id S261755AbVGKNzd (ORCPT ); Mon, 11 Jul 2005 09:55:33 -0400 From: Alistair John Strachan To: Ingo Molnar Subject: Re: Realtime Preemption, 2.6.12, Beginners Guide? Date: Mon, 11 Jul 2005 14:55:45 +0100 User-Agent: KMail/1.8.1 Cc: linux-kernel@vger.kernel.org References: <200507061257.36738.s0348365@sms.ed.ac.uk> <20050709155704.GA14535@elte.hu> <200507091704.12368.s0348365@sms.ed.ac.uk> In-Reply-To: <200507091704.12368.s0348365@sms.ed.ac.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200507111455.45105.s0348365@sms.ed.ac.uk> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Saturday 09 Jul 2005 17:04, Alistair John Strachan wrote: > On Saturday 09 Jul 2005 16:57, Ingo Molnar wrote: > > * Alistair John Strachan wrote: > > > Okay, I'll send you the vmlinux from -18 with a new digital photo, and > > > config, with CONFIG_4KSTACKS enabled. > > > > this crash too seems to indicate trigger_softirqs()/wakeup_softirqd(). > > Somewhere we somehow corrupt the stack and e.g. in oops7.jpg we return > > to 00c011ed. Note that it's a right-shifted address that could be one of > > these: > > > > c011ed50 t wakeup_softirqd > > c011ed80 t trigger_softirqs > > > > but it looks pretty weird. DEBUG_STACK_POISON (and the full-debug > > .config i sent) could perhaps uncover other types of stack corruptions. > > You weren't kidding about the overhead from DEBUG_STACK_POISON. > Unfortunately that config causes a triple fault randomly after boot. The > machine doesn't crash, or oops, it just resets. > > This problem has gone from bad to worse :-) Okay, maybe not. Some combination of the debug options you enabled causes this problem, but DEBUG_STACK_POISON itself is not the cause. Today I compiled Yet Another (tm) CONFIG_4KSTACKS kernel with DEBUG_STACK_POISON, CONFIG_DEBUG_STACKOVERFLOW and CONFIG_LATENCY_TRACE, which worked fine (from a random reboot perspective). I've also upgraded GCC to 4.0.1 as Jakub highlighted elsewhere in this thread that it had been released. Here's a screenshot of the oops. Notice that "stack left" is now -52. We've confirmed this is a stack overflow! http://devzero.co.uk/~alistair/oops8.jpeg I'm going to try the 8K stack kernel with the same stuff and see if I can get a stack trace. I hope this is the beginning of the end for this problem. -- Cheers, Alistair. personal: alistair()devzero!co!uk university: s0348365()sms!ed!ac!uk student: CS/CSim Undergraduate contact: 1F2 55 South Clerk Street, Edinburgh. EH8 9PP.