From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933819AbaE2FD6 (ORCPT ); Thu, 29 May 2014 01:03:58 -0400 Received: from mga09.intel.com ([134.134.136.24]:36131 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932950AbaE2EiF (ORCPT ); Thu, 29 May 2014 00:38:05 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.98,932,1392192000"; d="scan'208";a="519457147" Message-ID: <5386B939.5050009@intel.com> Date: Thu, 29 May 2014 12:36:09 +0800 From: Jet Chen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Ming Lei CC: Dongsu Park , Linux Kernel Mailing List , 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> <5386AAF4.4090804@intel.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/29/2014 12:13 PM, Ming Lei wrote: > On Thu, May 29, 2014 at 11:35 AM, Jet Chen wrote: >> On 05/29/2014 12:59 AM, Ming Lei wrote: >>> On Wed, May 28, 2014 at 11:42 PM, Ming Lei wrote: >>>> Hi Dongsu, >>>> >>>> On Wed, May 28, 2014 at 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; >>>> >>>> Would you mind explaining why bi_iter.bi_size need to be >>>> decreased by 'len'? In the failure path, it wasn't added by >>>> 'len', was it? >>> >>> Actually, the correct thing may be like what did in the >>> attached patch, as Maurizio discussed with me[1]. >>> >>> Very interestingly, I have reproduced the problem one time >>> with ext4/271 ext4/301 ext4/305, but won't with the attached >>> patch after running it for 3 rounds. >>> >>> [tom@localhost xfstests]$ sudo ./check ext4/271 ext4/301 ext4/305 >>> FSTYP -- ext4 >>> PLATFORM -- Linux/x86_64 localhost 3.15.0-rc7-next-20140527+ >>> MKFS_OPTIONS -- /dev/vdc >>> MOUNT_OPTIONS -- -o acl,user_xattr /dev/vdc /mnt/scratch >>> >>> ext4/271 1s ... 1s >>> ext4/301 31s ... 32s >>> ext4/305 181s ... 180s >>> Ran: ext4/271 ext4/301 ext4/305 >>> Passed all 3 tests >>> >>> Jet, could you test the attached patch? >> >> sorry, could you specify which patch need me to test ? >> actually I got confused. I only find > > Firstly, dongsu's patch is wrong, and it doesn't make sense to test > that. > > Secondly, it is the patch attached in my last email, and the > name is 'fix_compute_segments.patch'. > > Please let me know if you can find the patch, if you still can't, I > may resend to you. > Just got your email which attached that patch, thanks. I guess there is some network problem on my side which leads to some latency. Will test it out. > > Thanks, >