If blk_get_request() returns ENODEV then multipath_clone_and_map() causes a request to be requeued immediately. This can cause a kworker thread to spend 100% of the CPU time of a single core in __blk_mq_run_hw_queue() and also can cause device removal to never finish.
Avoid this by only requeuing after a delay if blk_get_request() fails. Additionally, reduce the requeue delay. Signed-off-by: Bart Van Assche <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: <[email protected]> --- drivers/md/dm-mpath.c | 2 +- drivers/md/dm-rq.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 39f9549b3300..e70f0e5bfcaf 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -517,7 +517,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, GFP_ATOMIC); if (IS_ERR(clone)) { /* EBUSY, ENODEV or EWOULDBLOCK: requeue */ - return r; + return DM_MAPIO_DELAY_REQUEUE; } clone->bio = clone->biotail = NULL; clone->rq_disk = bdev->bd_disk; diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 5f4e0c47516d..f3f986b08b6a 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -280,7 +280,7 @@ static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_ if (!rq->q->mq_ops) dm_old_requeue_request(rq); else - dm_mq_delay_requeue_request(rq, delay_requeue ? 5000 : 0); + dm_mq_delay_requeue_request(rq, delay_requeue ? 100/*ms*/ : 0); rq_completed(md, rw, false); } -- 2.12.0 -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
