From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH UPDATED 4/5] dm: implement REQ_FLUSH/FUA support for request-based dm Date: Thu, 02 Sep 2010 15:32:32 +0200 Message-ID: <4C7FA770.7070004@kernel.org> References: <1283162296-13650-1-git-send-email-tj@kernel.org> <1283162296-13650-5-git-send-email-tj@kernel.org> <20100830132836.GB5283@redhat.com> <4C7BB932.1070405@kernel.org> <4C7BD202.4040700@kernel.org> <4C7DFD8F.6070200@ct.jp.nec.com> <4C7FA531.7060300@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Mike Snitzer , jaxboe@fusionio.com, j-nomura@ce.jp.nec.com, jamie@shareable.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org, hch@lst.de To: Kiyoshi Ueda Return-path: In-Reply-To: <4C7FA531.7060300@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 09/02/2010 03:22 PM, Tejun Heo wrote: > Hello, > > On 09/01/2010 09:15 AM, Kiyoshi Ueda wrote: >> I don't see any obvious problem on this patch. >> However, I hit a NULL pointer dereference below when I use a mpath >> device with barrier option of ext3. I'm investigating the cause now. >> (Also I'm not sure the cause of the hang which Mike is hitting yet.) >> >> I tried on the commit 28dd53b26d362c16234249bad61db8cbd9222d0b of >> git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git flush-fua. >> >> # mke2fs -j /dev/mapper/mpatha >> # mount -o barrier=1 /dev/mapper/mpatha /mnt/0 >> # dd if=/dev/zero of=/mnt/0/a bs=512 count=1 >> # sync > > Hmm... I'm trying to reproduce this problem but hasn't been successful > yet. > >> BUG: unable to handle kernel NULL pointer dereference at 0000000000000078 >> IP: [] scsi_finish_command+0xa3/0x120 [scsi_mod] > > Can you please ask gdb which source line this is? Ooh, never mind. Reproduced it. Thanks. -- tejun