This is a note to let you know that I've just added the patch titled
blk-mq: don't insert passthrough request into sw queue
to the 6.4-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-don-t-insert-passthrough-request-into-sw-queu.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 645fc590b8aa63978875e3e6991d519c17ee62d5
Author: Ming Lei <ming.lei@xxxxxxxxxx>
Date: Wed Jun 21 21:22:08 2023 +0800
blk-mq: don't insert passthrough request into sw queue
[ Upstream commit 2293cae703cda162684ae966db6b1b4a11b5e88f ]
In case of real io scheduler, q->elevator is set, so blk_mq_run_hw_queue()
may just check if scheduler queue has request to dispatch, see
__blk_mq_sched_dispatch_requests(). Then IO hang may be caused because
all passthorugh requests may stay in sw queue.
And any passthrough request should have been inserted to hctx->dispatch
always.
Reported-by: Guangwu Zhang <guazhang@xxxxxxxxxx>
Fixes: d97217e7f024 ("blk-mq: don't queue plugged passthrough requests into scheduler")
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230621132208.1142318-1-ming.lei@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 c763f0bc66371..b9f4546139894 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2735,7 +2735,12 @@ static void blk_mq_dispatch_plug_list(struct blk_plug *plug, bool from_sched)
percpu_ref_get(&this_hctx->queue->q_usage_counter);
/* passthrough requests should never be issued to the I/O scheduler */
- if (this_hctx->queue->elevator && !is_passthrough) {
+ if (is_passthrough) {
+ spin_lock(&this_hctx->lock);
+ list_splice_tail_init(&list, &this_hctx->dispatch);
+ spin_unlock(&this_hctx->lock);
+ blk_mq_run_hw_queue(this_hctx, from_sched);
+ } else if (this_hctx->queue->elevator) {
this_hctx->queue->elevator->type->ops.insert_requests(this_hctx,
&list, 0);
blk_mq_run_hw_queue(this_hctx, from_sched);
