Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753188AbcJFG6D (ORCPT ); Thu, 6 Oct 2016 02:58:03 -0400 Received: from mail-vk0-f68.google.com ([209.85.213.68]:36014 "EHLO mail-vk0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752006AbcJFG6B (ORCPT ); Thu, 6 Oct 2016 02:58:01 -0400 MIME-Version: 1.0 In-Reply-To: <20161005213945.GA84123@kernel.org> References:

<20161005213945.GA84123@kernel.org> From: Sitsofe Wheeler Date: Thu, 6 Oct 2016 07:57:59 +0100 Message-ID: Subject: Re: kernel BUG at block/bio.c:1785 while trying to issue a discard to LVM on RAID1 md To: Shaohua Li Cc: Jens Axboe , linux-raid@vger.kernel.org, linux-block@vger.kernel.org, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2060 Lines: 48 On 5 October 2016 at 22:39, Shaohua Li wrote: > On Wed, Oct 05, 2016 at 10:31:11PM +0100, Sitsofe Wheeler wrote: >> On 3 October 2016 at 17:47, Sitsofe Wheeler wrote: >> > >> > While trying to do a discard (via blkdiscard --length 1048576 >> > /dev/) to an LVM device atop a two disk md RAID1 the >> > following oops was generated: >> > >> > [ 103.306243] md: resync of RAID array md127 >> > [ 103.306246] md: minimum _guaranteed_ speed: 1000 KB/sec/disk. >> > [ 103.306248] md: using maximum available idle IO bandwidth (but not >> > more than 200000 KB/sec) for resync. >> > [ 103.306251] md: using 128k window, over a total of 244194432k. >> > [ 103.308158] ------------[ cut here ]------------ >> > [ 103.308205] kernel BUG at block/bio.c:1785! >> >> This still seems to be here but slightly modified with a 4.8.0 kernel: > > Does this fix the issue? Looks there is IO error > > > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c > index 21dc00e..349eb11 100644 > --- a/drivers/md/raid1.c > +++ b/drivers/md/raid1.c > @@ -2196,7 +2196,6 @@ static int narrow_write_error(struct r1bio *r1_bio, int i) > wbio = bio_clone_mddev(r1_bio->master_bio, GFP_NOIO, mddev); > } > > - bio_set_op_attrs(wbio, REQ_OP_WRITE, 0); > wbio->bi_iter.bi_sector = r1_bio->sector; > wbio->bi_iter.bi_size = r1_bio->sectors << 9; > Yes the patch above fixes the issue and make blkdiscard just report that the BLKDISCARD ioctl failed. Since having this patch applied means the issue seen in http://www.gossamer-threads.com/lists/linux/kernel/2538757?do=post_view_threaded#2538757 (BUG at arch/x86/kernel/pci-nommu.c:66 / BUG at ./include/linux/scatterlist.h:90) can't be reached does that mean whatever was seen there is also spurious? Additionally as this issue seems to have been a problem going back to at least the 3.18 kernels, would a fix similar to this be eligible for stable kernels? -- Sitsofe | http://sucs.org/~sits/