From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758987AbZEEW1X (ORCPT ); Tue, 5 May 2009 18:27:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757479AbZEEW0x (ORCPT ); Tue, 5 May 2009 18:26:53 -0400 Received: from mail-gx0-f166.google.com ([209.85.217.166]:55358 "EHLO mail-gx0-f166.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754148AbZEEW0w convert rfc822-to-8bit (ORCPT ); Tue, 5 May 2009 18:26:52 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=PQ44+0feMIhLGXeyadoG3FA3RZ2tmVFuMSJPgPFbMOCcu1pVzz/PTtYR5Z6BwMlIfl MMjQBGnl0R3hGD30oTb53hVFDFdj8xbMq3hFPCMq/6sAo8zpS3m6bUbWlDqnVIZMzoHc Y2eRCUA6fWk3uBq3RzyZKGmVyZrLvdfzYFkZE= MIME-Version: 1.0 In-Reply-To: <20090505221403.GA4714@suse.de> References: <20090504220454.3F71148FB8@coco.kroah.org> <200905052036.24106.s.L-H@gmx.de> <20090505221403.GA4714@suse.de> Date: Wed, 6 May 2009 07:26:51 +0900 X-Google-Sender-Auth: da30a4c0cbca988d Message-ID: <2f11576a0905051526j73dd1570nb440e4b78e3b35a9@mail.gmail.com> Subject: Re: patch mm-fix-committed_as-underflow-on-large-nr_cpus-environment.patch added to 2.6.29-stable tree From: KOSAKI Motohiro To: Greg KH Cc: Stefan Lippers-Hollmann , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, cl@linux-foundation.org, dave@linux.vnet.ibm.com, ebmunson@us.ibm.com, mel@csn.ul.ie, stable@kernel.org 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 2009/5/6 Greg KH : > On Tue, May 05, 2009 at 08:36:19PM +0200, Stefan Lippers-Hollmann wrote: >> Hi >> >> On Dienstag, 5. Mai 2009, gregkh@suse.de wrote: >> [...] >> > From 00a62ce91e554198ef28234c91c36f850f5a3bc9 Mon Sep 17 00:00:00 2001 >> > From: KOSAKI Motohiro >> > Date: Thu, 30 Apr 2009 15:08:51 -0700 >> > Subject: mm: fix Committed_AS underflow on large NR_CPUS environment >> > >> > From: KOSAKI Motohiro >> > >> > commit 00a62ce91e554198ef28234c91c36f850f5a3bc9 upstream. >> > >> > The Committed_AS field can underflow in certain situations: >> > >> > >         # while true; do cat /proc/meminfo  | grep _AS; sleep 1; done | uniq -c >> > >               1 Committed_AS: 18446744073709323392 kB >> > >              11 Committed_AS: 18446744073709455488 kB >> > >               6 Committed_AS:    35136 kB >> > >               5 Committed_AS: 18446744073709454400 kB >> > >               7 Committed_AS:    35904 kB >> > >               3 Committed_AS: 18446744073709453248 kB >> > >               2 Committed_AS:    34752 kB >> > >               9 Committed_AS: 18446744073709453248 kB >> > >               8 Committed_AS:    34752 kB >> > >               3 Committed_AS: 18446744073709320960 kB >> > >               7 Committed_AS: 18446744073709454080 kB >> > >               3 Committed_AS: 18446744073709320960 kB >> > >               5 Committed_AS: 18446744073709454080 kB >> > >               6 Committed_AS: 18446744073709320960 kB >> > >> > Because NR_CPUS can be greater than 1000 and meminfo_proc_show() does >> > not check for underflow. >> > >> > But NR_CPUS proportional isn't good calculation.  In general, >> > possibility of lock contention is proportional to the number of online >> > cpus, not theorical maximum cpus (NR_CPUS). >> > >> > The current kernel has generic percpu-counter stuff.  using it is right >> > way.  it makes code simplify and percpu_counter_read_positive() don't >> > make underflow issue. >> >> This patch reproducably panics on all systems I could test so far on >> 2.6.29.2 + the current stable queue: >> - Acer Aspire One, Intel Atom N270, Intel 945GC chipset (i386) >> - AMD64 3200+, nVidia nforce3 chipset (amd64) >> - AMD64 X2 4200+, nVidia nforce4 chipset (amd64) >> >> Kernel panic (sorry, this is from a bad webcam and only the last part of >> the messages scrolling by - I can try to get a serial console tomorrow), >> taken from an AMD64 3200+, nVidia nforce3 chipset (amd64). >> http://sidux.com/slh/mm-fix-committed_as-underflow-on-large-nr_cpus-environment/panic.gif [198 KB] >> >> Reverting just this patch fixes the problem for me. >> >> Kernel configurations: >> http://sidux.com/slh/mm-fix-committed_as-underflow-on-large-nr_cpus-environment/config-2.6.29-2.slh.5.3-sidux-686   [96 KB] >> http://sidux.com/slh/mm-fix-committed_as-underflow-on-large-nr_cpus-environment/config-2.6.29-2.slh.5.6-sidux-amd64 [91 KB] > > Yes, I just confirmed this on my machines as well, so I'm going to drop > it from the stable queue. > > If anyone thinks it is really necessary for the 2.6.29-stable tree, > please resubmit it after fixing it and testing that it works :) > > thanks, Could you please post oops log? current mmotm (include this patch) works fine on my x86_64 box. Then, I have no hint now ;-)