This is a note to let you know that I've just added the patch titled Revert "dm: only run the queue on completion if congested or to the 4.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: revert-dm-only-run-the-queue-on-completion-if-congested-or.patch and it can be found in the queue-4.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 621739b00e16ca2d80411dc9b111cb15b91f3ba9 Mon Sep 17 00:00:00 2001 From: Mike Snitzer <snitzer@xxxxxxxxxx> Date: Wed, 8 Jul 2015 16:08:24 -0400 Subject: Revert "dm: only run the queue on completion if congested or no requests pending" From: Mike Snitzer <snitzer@xxxxxxxxxx> commit 621739b00e16ca2d80411dc9b111cb15b91f3ba9 upstream. This reverts commit 9a0e609e3fd8a95c96629b9fbde6b8c5b9a1456a. (Resolved a conflict during revert due to commit bfebd1cdb4 that came after) This revert is motivated by a couple failure reports on request-based DM multipath testbeds: 1) Netapp reported that their multipath fault injection test under heavy IO load can stall longer than 300 seconds. 2) IBM reported elevated lock contention in their testbed (likely due to increased back pressure due to IO not being dispatched as quickly): https://www.redhat.com/archives/dm-devel/2015-July/msg00057.html Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/md/dm.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1053,13 +1053,10 @@ static struct dm_rq_target_io *tio_from_ */ static void rq_completed(struct mapped_device *md, int rw, bool run_queue) { - int nr_requests_pending; - atomic_dec(&md->pending[rw]); /* nudge anyone waiting on suspend queue */ - nr_requests_pending = md_in_flight(md); - if (!nr_requests_pending) + if (!md_in_flight(md)) wake_up(&md->wait); /* @@ -1071,8 +1068,7 @@ static void rq_completed(struct mapped_d if (run_queue) { if (md->queue->mq_ops) blk_mq_run_hw_queues(md->queue, true); - else if (!nr_requests_pending || - (nr_requests_pending >= md->queue->nr_congestion_on)) + else blk_run_queue_async(md->queue); } Patches currently in stable-queue which might be from snitzer@xxxxxxxxxx are queue-4.1/revert-dm-only-run-the-queue-on-completion-if-congested-or.patch queue-4.1/bio-integrity-do-not-assume-bio_integrity_pool-exists-if-bioset-exists.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html