Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756983AbaAGArn (ORCPT ); Mon, 6 Jan 2014 19:47:43 -0500 Received: from mail-pd0-f174.google.com ([209.85.192.174]:36194 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750785AbaAGArj (ORCPT ); Mon, 6 Jan 2014 19:47:39 -0500 MIME-Version: 1.0 In-Reply-To: <20140106221036.GE9037@kmo> References: <20140102053101.GA29352@localhost> <20140106221036.GE9037@kmo> Date: Mon, 6 Jan 2014 16:47:38 -0800 Message-ID: Subject: Re: [block:for-3.14/core] kernel BUG at fs/bio.c:1748 From: Muthu Kumar To: Kent Overstreet Cc: Chris Mason , Fengguang Wu , Jens Axboe , linux-btrfs , linux-fsdevel , LKML , lkp@linux.intel.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org OK, after a bit more staring I believe the correct fix is the following. Fengguang, Please try this one? Regards, Muthu ------------ In btrfs_end_bio(), we increment bi_remaining if is_orig_bio. If not, we restore the orig_bio but failed to increment bi_remaining for orig_bio, which triggers a BUG_ON later when bio_endio is called. Fix is to increment bi_remaining when we restore the orig bio as well. Reported-by: fengguang.wu@intel.com CC: Kent Overstreet CC: Jens Axboe CC: Chris Mason ---------------- fs/btrfs/volumes.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 37972d5..2011cc0 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -5297,9 +5297,9 @@ static void btrfs_end_bio(struct bio *bio, int err) if (!is_orig_bio) { bio_put(bio); bio = bbio->orig_bio; - } else { - atomic_inc(&bio->bi_remaining); } + atomic_inc(&bio->bi_remaining); + bio->bi_private = bbio->private; bio->bi_end_io = bbio->end_io; btrfs_io_bio(bio)->mirror_num = bbio->mirror_num; -------------------------- On Mon, Jan 6, 2014 at 2:10 PM, Kent Overstreet wrote: > Chris, the patch below seems to be incorrect - with it we get hangs, so > bi_remaining (probably) isn't getting decremented when it should be. You sent > Jens fixes for btrfs which I somehow lost when I rebased, do you remember how > this is supposed to work? Looking at the code I'm not quite sure what's going on > here. > > On Fri, Jan 03, 2014 at 11:51:31AM -0800, Muthu Kumar wrote: >> Looks like Kent missed the btrfs endio in the original commit. How >> about this patch: >> >> --------- >> >> In btrfs_end_bio, call bio_endio_nodec on the restored bio so the >> bi_remaining is accounted for correctly. >> >> Reported-by: fengguang.wu@intel.com >> Cc: Kent Overstreet >> CC: Jens Axboe >> Signed-off-by: Muthukumar Ratty >> -------- >> >> fs/btrfs/volumes.c | 6 +++++- >> 1 files changed, 5 insertions(+), 1 deletions(-) >> >> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >> index f2130de..edfed52 100644 >> --- a/fs/btrfs/volumes.c >> +++ b/fs/btrfs/volumes.c >> @@ -5316,7 +5316,11 @@ static void btrfs_end_bio(struct bio *bio, int err) >> } >> kfree(bbio); >> >> - bio_endio(bio, err); >> + /* >> + * Call endio_nodec on the restored bio so the bi_remaining is >> + * accounted for correctly >> + */ >> + bio_endio_nodec(bio, err); >> } else if (!is_orig_bio) { >> bio_put(bio); >> } -- 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/