On Wed, May 03, 2023 at 03:52:05PM -0700, Bart Van Assche wrote:
> blk_mq_free_requests() calls dd_finish_request() indirectly. Prevent
> nested locking of dd->lock and dd->zone_lock by unlocking dd->lock
> before calling blk_mq_free_requests().
Do you have a reproducer for this that we could wire up in blktests?
Also please add a Fixes tag and move it to the beginning of the series.
> static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
> blk_insert_t flags)
> + __must_hold(dd->lock)
> {
> struct request_queue *q = hctx->queue;
> struct deadline_data *dd = q->elevator->elevator_data;
> @@ -784,7 +785,9 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
> }
>
> if (blk_mq_sched_try_insert_merge(q, rq, &free)) {
> + spin_unlock(&dd->lock);
> blk_mq_free_requests(&free);
> + spin_lock(&dd->lock);
> return;
Fiven that free is a list, why don't we declare the free list in
dd_insert_requests and just pass it to dd_insert_request and then do
one single blk_mq_free_requests call after the loop?
