From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762797AbXGPPTS (ORCPT ); Mon, 16 Jul 2007 11:19:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759824AbXGPPTI (ORCPT ); Mon, 16 Jul 2007 11:19:08 -0400 Received: from nz-out-0506.google.com ([64.233.162.236]:28543 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759253AbXGPPTG (ORCPT ); Mon, 16 Jul 2007 11:19:06 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=ta9h0qSXiFD28m7I2sJTvpp+UfnwfuCkbg80KBdhoUSspnjPwnbY6qreH2tJ1xu1C89te6sX6LE3sgqyerAD9wEd9cLx5YBszaMEice+pOAJAiebYh9LtamudSWMzZLNdoEenyQcYE0i4tEOHWcj/BpuOCvoc6OQglJy0mwny98= Message-ID: Date: Mon, 16 Jul 2007 20:49:03 +0530 From: "Satyam Sharma" To: "Gabriel C" Subject: Re: Oops while modprobing phy fixed module Cc: "Linux Kernel Mailing List" , "Christoph Lameter" , htejun@gmail.com, gregkh@suse.de In-Reply-To: <469B61C8.8010902@googlemail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <4698BF14.10807@googlemail.com> <469A5C94.7030201@googlemail.com> <469A9D5D.10509@googlemail.com> <469B61C8.8010902@googlemail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Gabriel, On 7/16/07, Gabriel C wrote: > ( http://194.231.229.228/Oops.txt ) > I cannot reproduce this on plain 2.6.22 so I've started to bisect the > problem. Could you reproduce this oops at will at the "bad" points? [ Note that git-bisect isn't quite applicable to bugs that are not 100% reproducible. The ones that passed as "good" may have passed only because the bug didn't get triggered on that particular test. Also, a perfectly good commit could get unnecessarily marked "bad" because the bug happened to get triggered for it ... so it's not quite trust-worthy for your case. ] > Here the bisect result: > > 3007e997de91ec59af39a3f9c91595b31ae6e08b is first bad commit > commit 3007e997de91ec59af39a3f9c91595b31ae6e08b > Author: Tejun Heo > Date: Thu Jun 14 04:27:23 2007 +0900 > > sysfs: use sysfs_mutex to protect the sysfs_dirent tree > > As kobj sysfs dentries and inodes are gonna be made reclaimable, > i_mutex can't be used to protect sysfs_dirent tree. Use sysfs_mutex > globally instead. As the whole tree is protected with sysfs_mutex, > there is no reason to keep sysfs_rename_sem. Drop it. > > While at it, add docbook comments to functions which require > sysfs_mutex locking. > > Signed-off-by: Tejun Heo > Signed-off-by: Greg Kroah-Hartman > > :040000 040000 9deba7887752bc343cc4f5dea2dac70e895ea8b6 > 75340b6e18c1ada500bb1a2b99ee88fd93ebae8c M fs Hmm, I don't see why this one could introduce an oops in SLUB, but it's doing some locking-related stuff, and if it didn't get it right, the resulting races /could/ lead to some oops. But ... a recently posted patch (http://lkml.org/lkml/2007/7/16/204) from Akinobu Mita does point to an oops that was introduced by commit 0c096b507f15397da890051ee73de4266d3941fb that belongs to the same patchset -- kmem_cache_free(NULL) is illegal and so will oops. A curious coincidence is that you do see sysfs_new_dirent() in the stack trace there, but the oops there is in kmem_cache_free(), not kmem_cache_zalloc() as your dmesg output indicated. Try that patch anyway, but I don't think that'll solve your problem -- if it was, you would've been seeing "unable to handle kernel NULL pointer dereference" but what you've been posting is "unable to handle kernel paging request at virtual address " ... Gaah. And the worst thing about it all is that we're not able to trigger the oops with debugging options -- that backtrace is horrible, so I'd suggest CONFIG_FRAME_POINTER, at the very least. And also perhaps DEBUG_INFO while we're at it -- that'll make later analysis easier, if nothing else. [ BTW I couldn't even get my compiler to generate the same "Code:" as we saw in your dmesg (I suspect all the oopsen have occurred with DEBUG=n, yes?) so my earlier analysis that suspected SLUB's page->lockless_freelist in slab_alloc() as the source of that invalid kernel address was actually based on some human-work rather than simple tools doing their thing. Gaah, again! ] I'm thoroughly mystified ... Christoph? Tejun? Someone? Satyam