Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261657AbVB1Pvh (ORCPT ); Mon, 28 Feb 2005 10:51:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261658AbVB1Pvh (ORCPT ); Mon, 28 Feb 2005 10:51:37 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:43494 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S261657AbVB1Pve (ORCPT ); Mon, 28 Feb 2005 10:51:34 -0500 Date: Mon, 28 Feb 2005 16:51:28 +0100 From: Jens Axboe To: Mark Haverkamp Cc: Linus Torvalds , Andrew Morton , linux-kernel , dm-devel@redhat.com Subject: Re: [PATCH] Fix panic in 2.6 with bounced bio and dm Message-ID: <20050228155127.GI8868@suse.de> References: <1109351021.5014.10.camel@markh1.pdx.osdl.net> <20050225161947.5fd6d343.akpm@osdl.org> <20050226123934.GA1254@suse.de> <1109604737.30227.3.camel@markh1.pdx.osdl.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1109604737.30227.3.camel@markh1.pdx.osdl.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1868 Lines: 51 On Mon, Feb 28 2005, Mark Haverkamp wrote: > On Sat, 2005-02-26 at 13:39 +0100, Jens Axboe wrote: > > On Fri, Feb 25 2005, Linus Torvalds wrote: > > > > > > > > > On Fri, 25 Feb 2005, Andrew Morton wrote: > > > > > > > > It seems very weird for dm to be shoving NULL page*'s into the middle of a > > > > bio's bvec array, so your fix might end up being a workaround pending a > > > > closer look at what's going on in there. > > > > > > Yes. I don't see how this patch can be anything but bandaid to hide the > > > real bug. Where do these "non-page" bvec's originate? > > > > Yep that's the fishy part, there should not be NULL pages in the middle > > (or empty bios, for that matter) submitted for io. > > > > Mark, what was the bug that triggered you to write this patch? > > It happened when some pages of IO from a dm device were bounced. It > looks to me when bio's are cloned in the dm code to split it for > physical devices that only the pointers to pages that apply to that > device are copied and th bi_idx is adjusted to point to the start, > leaving some NULL pointers at the start of the bio_vec. This should fix it. Signed-off-by: Jens Axboe ===== mm/highmem.c 1.55 vs edited ===== --- 1.55/mm/highmem.c 2005-01-08 06:44:13 +01:00 +++ edited/mm/highmem.c 2005-02-28 16:50:59 +01:00 @@ -425,7 +425,7 @@ * at least one page was bounced, fill in possible non-highmem * pages */ - bio_for_each_segment(from, *bio_orig, i) { + __bio_for_each_segment(from, *bio_orig, i) { to = bio_iovec_idx(bio, i); if (!to->bv_page) { to->bv_page = from->bv_page; -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/