From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760658AbXGIWlP (ORCPT ); Mon, 9 Jul 2007 18:41:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760718AbXGIWkq (ORCPT ); Mon, 9 Jul 2007 18:40:46 -0400 Received: from rgminet01.oracle.com ([148.87.113.118]:26208 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760716AbXGIWko (ORCPT ); Mon, 9 Jul 2007 18:40:44 -0400 Date: Mon, 9 Jul 2007 15:44:15 -0700 From: Randy Dunlap To: "Jesper Juhl" Cc: "Charles Shannon Hendrix" , linux-kernel@vger.kernel.org Subject: Re: BUG: kernel crash report, odd... Message-Id: <20070709154415.a657db36.randy.dunlap@oracle.com> In-Reply-To: <9a8748490707091529j153d7202s47596b78b7aac612@mail.gmail.com> References: <20070709220848.GA6782@widomaker.com> <9a8748490707091519g3a0a098dx1e9188083c5a74b4@mail.gmail.com> <9a8748490707091529j153d7202s47596b78b7aac612@mail.gmail.com> Organization: Oracle Linux Eng. X-Mailer: Sylpheed 2.4.2 (GTK+ 2.8.10; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAAI= X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-Whitelist: TRUE Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Jul 2007 00:29:54 +0200 Jesper Juhl wrote: > Forgot a few things, see below... > > On 10/07/07, Jesper Juhl wrote: > > On 10/07/07, Charles Shannon Hendrix wrote: > > > > > > A system I was using a few minutes ago dumped this to the syslog: > > > > > > Jul 9 17:50:38 daydream kernel: [76022.613000] BUG: unable to handle > > > kernel NUL > > > L pointer dereference at virtual address 00000010 > > > Jul 9 17:50:38 daydream kernel: [76022.613000] printing eip: > > > Jul 9 17:50:38 daydream kernel: [76022.613000] c01ace66 > > > Jul 9 17:50:38 daydream kernel: [76022.613000] *pde = 00000000 > > > Jul 9 17:50:38 daydream kernel: [76022.613000] Oops: 0000 [#1] > > > > > > > > > There was no other information either before or after. > > > > > > What I saw was my KDE desktop stopped responding to events. > > > > > > Machine didn't respond to power switch. > > > > > > Unfortunately, that's all I know. > > > > > > In the past when I had bugs like this, I got a fairly extensive kernel > > > error message, but this time the above is the only thing I saw. > > > > > It does look a little short... probably the rest just didn't make it to disk... > > > > > I have not had kernel bugs like this until I started running 2.6.20 on a > > > new Kubuntu install. > > > > > > Same hardware, but Slackware and my own custom 2.6.19 kernel never > > > crashed. > > > > > Different kernel source version, different configuration, probably > > different compiler, Slackware doesn't patch the vanilla kernel - I > > believe (k)ubuntu does. All in all that equals a significantly > > different kernel binary you have been running in those two cases. > > > A different userspace could also be the cause. In theory, userspace > should never be able to crash the kernel, but in real life bugs happen > and sometimes userspace manages to cause a kernel crash. So, a > different userspace environment in your new distribution could in > theory expose a bug that didn't surface with your previous > distribution. > > > > Is there anything I can do, in case this happens again, to try and > > > capture more information? > > > > > 0. Make sure the kernels loglevel is set so that you get all messages. i.e., boot with "ignore_loglevel" > 0.5. Perhaps increase the size of the kernels log buffer (the > LOG_BUF_SHIFT config option) or boot with "log_buf_len=n[KMG]" (power of 2 required) > > 1. Make sure syslog is setup to capture all kernel messages, both > > errors, warnings, notices, debug messages etc. > > > > 2. If you can, check output of 'dmesg' instead of just what made it to syslog. > > > > 3. If you have a second PC, setup serial console or netconsole to > > capture kernel messages on that second box. This can sometimes capture > > messages that don't make it to disk. > > > > 4. Build a custom kernel with some (or all) of the debug options under > > the Kernel Hacking menu enabled. > > > > 5. Even when the system hangs you may in some cases be able to get > > some info (or just sync the disks and do a reboot) via magic sysrq. --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***