Commit 3280d66a authored Aug 14, 2017 by Keith Busch Committed by Jens Axboe Aug 15, 2017

blk-mq: Fix queue usage on failed request allocation



blk_mq_get_request() does not release the callers queue usage counter
when allocation fails. The caller still needs to account for its own
queue usage when it is unable to allocate a request.

Fixes: 1ad43c00 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed")

Reported-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Tested-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent ef954844

block/blk-mq.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -360,12 +360,12 @@ struct request blk_mq_alloc_request(struct request_queue q, unsigned int op,
		return ERR_PTR(ret);

		rq = blk_mq_get_request(q, NULL, op, &alloc_data);
		blk_queue_exit(q);

		if (!rq)
		return ERR_PTR(-EWOULDBLOCK);

		blk_mq_put_ctx(alloc_data.ctx);
		blk_queue_exit(q);

		rq->__data_len = 0;
		rq->__sector = (sector_t) -1;
		@@ -411,12 +411,11 @@ struct request blk_mq_alloc_request_hctx(struct request_queue q,
		alloc_data.ctx = __blk_mq_get_ctx(q, cpu);

		rq = blk_mq_get_request(q, NULL, op, &alloc_data);
		blk_queue_exit(q);

		if (!rq)
		return ERR_PTR(-EWOULDBLOCK);

		blk_queue_exit(q);

		return rq;
		}
		EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);