From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755909Ab0CQTfk (ORCPT ); Wed, 17 Mar 2010 15:35:40 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:53562 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755765Ab0CQTfi (ORCPT ); Wed, 17 Mar 2010 15:35:38 -0400 Date: Wed, 17 Mar 2010 20:35:27 +0100 From: Ingo Molnar To: "Paul E. McKenney" , =?unknown-8bit?B?RnLDqWTDqXJpYw==?= Weisbecker , Steven Rostedt Cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org Subject: Re: [tip:core/rcu] rcu: Fix holdoff for accelerated GPs for last non-dynticked CPU Message-ID: <20100317193527.GA12584@elte.hu> References: <1267311188-16603-1-git-send-email-paulmck@linux.vnet.ibm.com> <20100316110036.GA4554@elte.hu> <20100316110323.GA31038@elte.hu> <20100317175311.GA5187@elte.hu> <20100317192241.GB6806@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100317192241.GB6806@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Paul E. McKenney wrote: > On Wed, Mar 17, 2010 at 06:53:11PM +0100, Ingo Molnar wrote: > > > > * Ingo Molnar wrote: > > > > > incidentally i have a RCU badness crash log from another box: > > > > > > [ 4.573332] initcall ipmi_init_msghandler_mod+0x0/0xd returned 0 after 0 usecs > > > [ 4.573332] calling init_ipmi_si+0x0/0x435 @ 1 > > > [ 4.573332] IPMI System Interface driver. > > > [ 4.573340] [] no_context+0x1fc/0x20b > > > [ 4.576672] [] ? ftrace_call+0x5/0x2b > > > [ 4.580021] [] __bad_area_nosemaphore+0x18c/0x1af > > > [ 4.583338] [] ? ftrace_call+0x5/0x2b > > > [ 4.586672] [] bad_area_nosemaphore+0x13/0x15 > > > [ 4.590005] [] do_page_fault+0x138/0x284 > > > [ 4.593354] [] page_fault+0x1f/0x30 > > > > I spent a few hours yesterday and today trying to track this down, but failed > > to bisect it. The crash is sporadic on many configs - which confused my > > bisection attempts. Sometimes it crashes only after 10 reboots. Was able to > > crash v2.6.30 as well, so it's an older bug. v2.6.29 was not testable on that > > box due to network driver problems so i stopped there. > > OK, I give up... > > What did you change about your testing? ;-) Nothing really - and it has not reoccured on that box since i let it move on to another random config. This might be a 1:100000 kind of blue moon bug. (literally) My suspicion is that it's an ftrace bug, all the crashes happened during function-tracer self-tests. Ingo