Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935755Ab0GPH3p (ORCPT ); Fri, 16 Jul 2010 03:29:45 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:40041 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935639Ab0GPH3o convert rfc822-to-8bit (ORCPT ); Fri, 16 Jul 2010 03:29:44 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=d21NXW5aLsZ7agC8cXQb4vAF/1zdVcb1zu3tqgDkPSA1SISh6RzMgevZLnqfAtUYKE bq3AZ4zvsbRm9BNcYu9SPe3KBdP63jvC+TV1dvckP/x3ZD7TBzmSzmAb4L2FVOMkrEa8 BvYQwABMQeiBkmrIwq4kchpt9cQGfRPsx+X68= MIME-Version: 1.0 In-Reply-To: References: <1279100846.8592.53.camel@e102109-lin.cambridge.arm.com> <4C3D89AC.4040303@cs.helsinki.fi> <1279205891.6664.46.camel@e102109-lin.cambridge.arm.com> <4C3F2F52.2050101@cs.helsinki.fi> <20100715162805.GA10240@brouette> <20100715191638.GA3694@brouette> <20100715200012.GA4175@brouette> Date: Fri, 16 Jul 2010 09:29:42 +0200 Message-ID: Subject: Re: kmemleak, cpu usage jump out of nowhere From: Zeno Davatz To: Pekka Enberg Cc: Damien Wyart , Catalin Marinas , "linux-kernel@vger.kernel.org" , Andrew Morton , "x86@kernel.org" , "mingo@elte.hu" , "yinghai@kernel.org" , Peter Zijlstra Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3564 Lines: 84 On Thu, Jul 15, 2010 at 10:50 PM, Pekka Enberg wrote: > On Thu, Jul 15, 2010 at 11:38 PM, Zeno Davatz wrote: >> Am 15.07.2010 um 22:00 schrieb Damien Wyart : >> >>>>> For now, I can't reproduce the problem with CONFIG_NO_BOOTMEM disabled ; >>>>> with the option and rc5 the problem was happening quite quickly after >>>>> boot and normal use of the machine. So it seems I can confirme what Zeno >>>>> has seen and I hope this will give a hint to debug the problem. I guess >>>>> this has not been reported that much because many testers might not have >>>>> enabled CONFIG_NO_BOOTMEM... Maybe the scheduler folks could test their >>>>> benchmark with a kernel having this option enabled? >>> >>> * Pekka Enberg [2010-07-15 22:50]: >>>> To be honest, the bug is bit odd. It's related to boot-time memory >>>> allocator changes but yet it seems to manifest itself as a scheduling >>>> problem. So if you have some spare time and want to speed up the >>>> debugging process, please test v2.6.34 and v2.6.35-rc1 with >>>> CONFIG_NO_BOOTMEM and if former is good and latter is bad, try to see >>>> if you can identify the offending commit with "git bisect." >>> >>> Not sure I will have enough time in the coming days (doing that remotely >>> is fishy since ssh access is almost stuck when the problem occurs); if >>> Zeno can and would like to do it, maybe this could be done faster. >>> >>> As the scheduler is now very well instrumented (many debugging features >>> are available), reproducing the bug on a test platform (it happens quite >>> quickly for me) might also give some hints. So testers, if you have >>> time, please test 2.6.35-rc5 with CONFIG_NO_BOOTMEM on a Core i7 and see >>> if you can reproduce the problem! >> >> Will try to do so. Can you point me to the git bisect howto with the versions you want. > > Cool. So like I said, you first want to test 2.6.34 to find a known > good version. Please remember to make sure you have CONFIG_NO_BOOTMEM > enabled. You can also try to speed up the process by testing > 2.6.35-rc1 which is likely to include the offending commit. That's not > strictly necessary as long as you are sure that you have some > 2.6.35-rc kernel that's bad. > > After that, bisecting is as simple as: > > ?git bisect start > ?git bisect good v2.6.34 > ?git bisect bad v2.6.31-rc1 # or some other kernel you know to be bad > ? > > then > > ?git bisect bad # if you were able to trigger the problem > > or > > ?git bisect good # if the problem doesn't exist > > git will then find the next revision to test after which you do > > ? > > and repeat the "git bisect good/bad" step until git tells you it has > found the offending commit. > > There's more information on the git bisect man pages: > > http://www.kernel.org/pub/software/scm/git/docs/git-bisect.html > > Let me know if you need more help with this. This one also causes a panic: http://www.flickr.com/photos/zrr/4798092747/in/photostream/ but this version boots just fine again: Linux zenogentoo 2.6.34-05459-gac3ee84 #102 SMP Fri Jul 16 09:22:25 CEST 2010 i686 Intel(R) Core(TM) i7 CPU 960 @ 3.20GHz GenuineIntel GNU/Linux Best Zeno -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/