From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753479Ab2LPTli (ORCPT ); Sun, 16 Dec 2012 14:41:38 -0500 Received: from mail-ea0-f174.google.com ([209.85.215.174]:57064 "EHLO mail-ea0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752592Ab2LPTlh convert rfc822-to-8bit (ORCPT ); Sun, 16 Dec 2012 14:41:37 -0500 From: Maciej Rutecki Reply-To: maciej.rutecki@gmail.com To: =?utf-8?q?Bj=C3=B8rn_Mork?= Subject: Re: Bisected oops regression between v3.7-rc8 and v3.7: nmi_watchdog Date: Sun, 16 Dec 2012 20:41:32 +0100 User-Agent: KMail/1.13.7 (Linux/3.7.0; KDE/4.8.4; x86_64; ; ) Cc: linux-kernel@vger.kernel.org, Norbert Warmuth , Joseph Salisbury , Thomas Gleixner References: <87y5h1c70y.fsf@nemi.mork.no> In-Reply-To: <87y5h1c70y.fsf@nemi.mork.no> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Message-Id: <201212162041.32350.maciej.rutecki@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On piątek, 14 grudnia 2012 o 10:33:33 Bjørn Mork wrote: > Hello, > > I was a bit surprised by v3.7 hanging "all the time", usually just > freezing but sometimes with a stack dump pointing to timerqueue_del > calling rb_erase and oopsing there. Of course I could never make it dump > anything when prepared to capture it via netconsole, so the best I have > is this picture: http://www.mork.no/~bjorn/20121213_203557.jpg > > I discovered that the freeze was related to plugging AC power and > started bisecting from v3.7-rc3, which I had been running for quite a > while and therefore was confident did not have this problem. The bisect > log ended up as this: > > bjorn@canardo:/usr/local/src/build-tmp/linux$ git bisect log > # bad: [29594404d7fe73cd80eaa4ee8c43dcc53970c60e] Linux 3.7 > # good: [8f0d8163b50e01f398b14bcd4dc039ac5ab18d64] Linux 3.7-rc3 > git bisect start 'v3.7' 'v3.7-rc3' > # good: [29282fde80d44e587f8c152b10049a56e61659f0] KVM: x86: Fix invalid > secondary exec controls in vmx_cpuid_update() git bisect good > 29282fde80d44e587f8c152b10049a56e61659f0 > # good: [2654ad44b5f7a5f1b12d722a37d9b9df69d57899] Merge branch > 'x86-urgent-for-linus' of > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip git bisect good > 2654ad44b5f7a5f1b12d722a37d9b9df69d57899 > # good: [086486e46e4206cfa1140fb9682ad67c8a4502fb] Merge branch 'for-linus' > of git://git.samba.org/sfrench/cifs-2.6 git bisect good > 086486e46e4206cfa1140fb9682ad67c8a4502fb > # good: [25a3bc6bd1ca03ab504b8c55c98f8d0135644d53] [parisc] open(2) compat > bug git bisect good 25a3bc6bd1ca03ab504b8c55c98f8d0135644d53 > # bad: [cfd1f032f98e5ab3a04f23a0adbd53ff8744827d] Merge branch > 'core-urgent-for-linus' of > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip git bisect bad > cfd1f032f98e5ab3a04f23a0adbd53ff8744827d > # good: [b69f0859dc8e633c5d8c06845811588fe17e68b3] Linux 3.7-rc8 > git bisect good b69f0859dc8e633c5d8c06845811588fe17e68b3 > # good: [ca50496eb487b639de1f502e77a48dde84152fb9] Merge branch > 'for-3.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq git > bisect good ca50496eb487b639de1f502e77a48dde84152fb9 > # good: [70dcc535bdf30ffaef58b867fbde45c0287f34c6] Merge tag > 'upstream-3.7-rc9' of git://git.infradead.org/linux-ubi git bisect good > 70dcc535bdf30ffaef58b867fbde45c0287f34c6 > # good: [df2fc246c8ee8b6067af1fa55d3bc23107457f61] Merge branch 'fixes' of > git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux git bisect good > df2fc246c8ee8b6067af1fa55d3bc23107457f61 > # bad: [8d4516904b39507458bee8115793528e12b1d8dd] watchdog: Fix CPU hotplug > regression git bisect bad 8d4516904b39507458bee8115793528e12b1d8dd > > > and I can confirm that reverting 8d451690 does fix the problem. After > having found this, it became clearer to me why the freeze was related to > plugging AC power: I use laptop-mode-tools in its default Debian > configuration, which will disable the nmi_watchdog on battery power and > enable it on AC power. > > So the simple test case which will hang my (and presumably also your) PC > on plain v3.7 is: > > echo 0 > /proc/sys/kernel/nmi_watchdog > echo 1 > /proc/sys/kernel/nmi_watchdog > > without any cmdline nmi_watchdog parameters, i.e. enabled. > > I'll followup with a proposed revert patch, but I guess you will want to > come up with something which fixes the original problem as well. But > given the serious effect of the bug, causing a 100% reproducable freeze > on a standard distro laptop setup, I hope that the revert will go into > v3.7.1 unless a real fix can be prepared in time. > > > Thanks, > Bjørn Confirm similar behaviour (I didn't do bisection): kernel sometimes opps when plug in AC adapter. Regards -- Maciej Rutecki http://www.mrutecki.pl