From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755278AbYFXSj6 (ORCPT ); Tue, 24 Jun 2008 14:39:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751778AbYFXSju (ORCPT ); Tue, 24 Jun 2008 14:39:50 -0400 Received: from bu3sch.de ([62.75.166.246]:40343 "EHLO vs166246.vserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751237AbYFXSjt (ORCPT ); Tue, 24 Jun 2008 14:39:49 -0400 From: Michael Buesch To: Jan Kara Subject: Re: Oops when using growisofs Date: Tue, 24 Jun 2008 20:39:18 +0200 User-Agent: KMail/1.9.6 (enterprise 0.20070907.709405) Cc: Andrew Morton , Arnd Bergmann , linux-kernel , Jens Axboe , Jan Kara References: <200806221818.24372.mb@bu3sch.de> <20080622233448.4b27c131.akpm@linux-foundation.org> <20080624172812.GD22586@atrey.karlin.mff.cuni.cz> In-Reply-To: <20080624172812.GD22586@atrey.karlin.mff.cuni.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200806242039.18755.mb@bu3sch.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 24 June 2008 19:28:12 Jan Kara wrote: > > On Mon, 23 Jun 2008 00:28:20 +0200 Michael Buesch wrote: > > > > > On Monday 23 June 2008 00:05:51 Michael Buesch wrote: > > > > > Note: r9 and r3 are both NULL pointers. r3 is the value returned from alloc_page_buffers. > > > > > R9 is a copy of that, which gets accessed. > > > > > > > > Hm, yeah. I looked at that code already, but I can't see how it could return > > > > a NULL pointer. > > > > > > Well, actually, it can return a NULL pointer. > > > > > > 928 head = NULL; > > > 929 offset = PAGE_SIZE; > > > 930 while ((offset -= size) >= 0) { > > > ... > > > 949 } > > > 950 return head; > > > > > > So if size, which is a passed in as parameter, is > PAGE_SIZE it will return NULL. > > > > > > The size parameter is calculated by doing > > > blocksize = 1 << inode->i_blkbits; > > > in an earlier function in the callchain. > > > > Yes, that's a more likely scenario. isofs has a history of passing > > garbage into the VFS. > > > > > So, well. I dunno what i_blkbits is. There's no docs in struct inode. > > > > It's log2 of the filesystem blocksize. It'd be interesting to work out > > what value isofs is setting it to, and why. > Well, yes, that looks as a reason at the first sight. But what I don't > get is, how can isofs possibly set such a blocksize when it uses > sb_set_blocksize() which checks whether blocksize isn't larger than page > size... So it must be something less obvious. > bd_set_size() can possibly set blocksize larger than PAGE_SIZE and > it's called from do_open() but it uses bdev_hardsect_size() and that > shouldn't be larger than PAGE_SIZE either (at least drivers seem to take > care of this). > I have seen one more report of this Oops for SLES10 kernel and also in that > case an IO error happened so probably that is a trigger... But so far I > don't get the details. Yeah the IO error is the trigger. I noticed that it had obvious troubles accessing the DVD that was in the drive. It sweeped over it for several seconds, then hung the system for 2 or 3 seconds and then oopsed. But after that everything continued to work as usual. (Except kded of course) -- Greetings Michael.