Received: with ECARTIS (v1.0.0; list xfs); Mon, 22 Jan 2007 19:28:02 -0800 (PST) X-Spam-oss-Status: No, score=-2.6 required=5.0 tests=BAYES_00 autolearn=ham version=3.2.0-pre1-r497472 Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.191]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id l0N3Rtqw014708 for ; Mon, 22 Jan 2007 19:27:57 -0800 Received: by nf-out-0910.google.com with SMTP id x30so87037nfb for ; Mon, 22 Jan 2007 19:27:02 -0800 (PST) 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=YyPyqkif8t9RDwskczse5LiMPC6QKh4KCunEEhev/m5UCY6L5HrffWLTZehiTS+g+69dBURTq5ETIaxomAk3IZaO/Z7eLSL6b7LTpIht17I1Lz5JK1bBBf98/M1UmgCo8w1SlEo0m3bpFLmYGIZD6/+3fGqcNwCg+FIN+cNCeM4= Received: by 10.82.138.6 with SMTP id l6mr6182903bud.1169516651781; Mon, 22 Jan 2007 17:44:11 -0800 (PST) Received: by 10.82.176.11 with HTTP; Mon, 22 Jan 2007 17:44:11 -0800 (PST) Message-ID: Date: Mon, 22 Jan 2007 18:44:11 -0700 From: "Dan Williams" To: "Neil Brown" Subject: Re: Kernel 2.6.19.2 New RAID 5 Bug (oops when writing Samba -> RAID5) Cc: "Chuck Ebbert" , "Justin Piszcz" , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, xfs@oss.sgi.com In-Reply-To: <17845.13256.284461.992275@notabene.brown> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <45B5261B.1050104@redhat.com> <17845.13256.284461.992275@notabene.brown> X-archive-position: 10377 X-ecartis-version: Ecartis v1.0.0 Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com X-original-sender: dan.j.williams@gmail.com Precedence: bulk X-list: xfs Content-Length: 1245 Lines: 36 On 1/22/07, Neil Brown wrote: > On Monday January 22, cebbert@redhat.com wrote: > > Justin Piszcz wrote: > > > My .config is attached, please let me know if any other information is > > > needed and please CC (lkml) as I am not on the list, thanks! > > > > > > Running Kernel 2.6.19.2 on a MD RAID5 volume. Copying files over Samba to > > > the RAID5 running XFS. > > > > > > Any idea what happened here? > .... > > > > > Without digging too deeply, I'd say you've hit the same bug Sami Farin > > and others > > have reported starting with 2.6.19: pages mapped with kmap_atomic() > > become unmapped > > during memcpy() or similar operations. Try disabling preempt -- that > > seems to be the > > common factor. > > That is exactly the conclusion I had just come to (a kmap_atomic page > must be being unmapped during memcpy). I wasn't aware that others had > reported it - thanks for that. > > Turning off CONFIG_PREEMPT certainly seems like a good idea. > Coming from an ARM background I am not yet versed in the inner workings of kmap_atomic, but if you have time for a question I am curious as to why spin_lock(&sh->lock) is not sufficient pre-emption protection for copy_data() in this case? > NeilBrown Regards, Dan