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 <bart.vanassche@xxxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
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
--
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