From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Torsten Kaiser , Peter Maloney , NeilBrown Subject: [ 15/27] md/raid1{,0}: fix deadlock in bitmap_unplug. Date: Thu, 6 Dec 2012 16:58:59 -0800 Message-Id: <20121207005830.182431944@linuxfoundation.org> In-Reply-To: <20121207005825.232489605@linuxfoundation.org> References: <20121207005825.232489605@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit 874807a83139abc094f939e93623c5623573d543 upstream. If the raid1 or raid10 unplug function gets called from a make_request function (which is very possible) when there are bios on the current->bio_list list, then it will not be able to successfully call bitmap_unplug() and it could need to submit more bios and wait for them to complete. But they won't complete while current->bio_list is non-empty. So detect that case and handle the unplugging off to another thread just like we already do when called from within the scheduler. RAID1 version of bug was introduced in 3.6, so that part of fix is suitable for 3.6.y. RAID10 part won't apply. Reported-by: Torsten Kaiser Reported-by: Peter Maloney Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman --- drivers/md/raid1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -958,7 +958,7 @@ static void raid1_unplug(struct blk_plug struct r1conf *conf = mddev->private; struct bio *bio; - if (from_schedule) { + if (from_schedule || current->bio_list) { spin_lock_irq(&conf->device_lock); bio_list_merge(&conf->pending_bio_list, &plug->pending); conf->pending_count += plug->pending_cnt;