This is a note to let you know that I've just added the patch titled blk-mq: Put driver tag in blk_mq_dispatch_rq_list() when no budget to the 5.4-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: blk-mq-put-driver-tag-in-blk_mq_dispatch_rq_list-whe.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 16018457b490cb1f4a0f28d383621f1aa25a4fb8 Author: John Garry <john.garry@xxxxxxxxxx> Date: Thu Apr 16 19:18:51 2020 +0800 blk-mq: Put driver tag in blk_mq_dispatch_rq_list() when no budget [ Upstream commit 5fe56de799ad03e92d794c7936bf363922b571df ] If in blk_mq_dispatch_rq_list() we find no budget, then we break of the dispatch loop, but the request may keep the driver tag, evaulated in 'nxt' in the previous loop iteration. Fix by putting the driver tag for that request. Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Signed-off-by: John Garry <john.garry@xxxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/block/blk-mq.c b/block/blk-mq.c index a8c1a45cedde0..757c0fd9f0cc2 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1232,8 +1232,10 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list, rq = list_first_entry(list, struct request, queuelist); hctx = rq->mq_hctx; - if (!got_budget && !blk_mq_get_dispatch_budget(hctx)) + if (!got_budget && !blk_mq_get_dispatch_budget(hctx)) { + blk_mq_put_driver_tag(rq); break; + } if (!blk_mq_get_driver_tag(rq)) { /*