From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755873AbaE2DVk (ORCPT ); Wed, 28 May 2014 23:21:40 -0400 Received: from mga02.intel.com ([134.134.136.20]:19659 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755546AbaE2DVh (ORCPT ); Wed, 28 May 2014 23:21:37 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.98,932,1392192000"; d="scan'208";a="548160720" Message-ID: <5386A7AE.60000@intel.com> Date: Thu, 29 May 2014 11:21:18 +0800 From: Jet Chen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Dongsu Park , linux-kernel@vger.kernel.org CC: Jens Axboe , Maurizio Lombardi Subject: Re: [PATCH] bio: decrease bi_iter.bi_size by len in the fail path References: <20140527112459.GF2205@dhcp-27-189.brq.redhat.com> <1401289778-9840-1-git-send-email-dongsu.park@profitbricks.com> In-Reply-To: <1401289778-9840-1-git-send-email-dongsu.park@profitbricks.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/28/2014 11:09 PM, Dongsu Park wrote: > From: Dongsu Park > > Commit 3979ef4dcf3d1de55a560a3a4016c30a835df44d ("bio-modify- > __bio_add_page-to-accept-pages-that-dont-start-a-new-segment-v3") > introduced a regression as reported by Jet Chen. > That results in a kernel BUG at drivers/block/virtio_blk.c:166. > > To fix that, bi_iter.bi_size must be decreased by len, before > recounting the number of physical segments. > > Tested on with kernel 3.15.0-rc7-next-20140527 on qemu guest, > by running xfstests/ext4/271. > > Cc: Jens Axboe > Cc: Jet Chen > Cc: Maurizio Lombardi > Signed-off-by: Dongsu Park > --- > block/bio.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/block/bio.c b/block/bio.c > index 0443694ccbb4..67d7cba1e5fd 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -810,6 +810,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page > bvec->bv_len = 0; > bvec->bv_offset = 0; > bio->bi_vcnt--; > + bio->bi_iter.bi_size -= len; > blk_recount_segments(q, bio); > return 0; > } > This patch fixes the problem. Tested-by: Jet Chen