From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755105Ab0BHKHc (ORCPT ); Mon, 8 Feb 2010 05:07:32 -0500 Received: from www.tglx.de ([62.245.132.106]:51907 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753792Ab0BHKHb (ORCPT ); Mon, 8 Feb 2010 05:07:31 -0500 Date: Mon, 8 Feb 2010 11:06:58 +0100 (CET) From: Thomas Gleixner To: Andreas Mohr cc: linux-kernel@vger.kernel.org, Ingo Molnar , John Stultz Subject: Re: clocksource mutex deadlock, cat current_clocksource (2.6.33-rc6/7) In-Reply-To: <20100208093719.GA15428@rhlx01.hs-esslingen.de> Message-ID: References: <20100206142141.GA12871@rhlx01.hs-esslingen.de> <20100207191949.GA23665@rhlx01.hs-esslingen.de> <20100208053830.GA7128@rhlx01.hs-esslingen.de> <20100208093719.GA15428@rhlx01.hs-esslingen.de> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 8 Feb 2010, Andreas Mohr wrote: > > Nope, the NMI watchdog is not involved. It merily tells us that the > > task is stuck. > > OK. > And after that message debug_locks is zeroed and kwatchdog is gone > from the process list (probably during debug_locks change). Oh, no. kwatchdog is a run once thread. It always exits after work is done, but I'm pretty confused about the NMI watchdog output. EIP: 0060:[] EFLAGS: 00000082 CPU: 0 EIP is at timekeeping_forward_now+0x116/0x139 I don't see what might make the machine stuck here. Can you decode the source line with "addr2line -e vmlinux c1045170" please ? > I'll explain what I think might be happening: > bootup switches to acpi_pm, timekeeping gets borked, NMI watchdog complains > due to timekeeping issues, brutally yanks the waiting acpi_pm switchover > (thereby NOT releasing clocksource_mutex), No, the NMI watchdog does not yank anything. It just reports. Thanks, tglx