This is a note to let you know that I've just added the patch titled blk-mq: Fix potential io hung for shared sbitmap per tagset to the 6.2-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-fix-potential-io-hung-for-shared-sbitmap-per-.patch and it can be found in the queue-6.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 1390a67a4d059d9317813843bebfd0357c7e1f7b Author: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> Date: Wed Jan 18 17:37:16 2023 +0800 blk-mq: Fix potential io hung for shared sbitmap per tagset [ Upstream commit 47df9ce95cd568d3f84218c4f65e9fbd4dfeda55 ] Commit f906a6a0f4268 ("blk-mq: improve tag waiting setup for non-shared tags") mark restart for unshared tags for improvement. At that time, tags is only shared betweens queues and we can check if tags is shared by test BLK_MQ_F_TAG_SHARED. Afterwards, commit 32bc15afed04b ("blk-mq: Facilitate a shared sbitmap per tagset") enabled tags share betweens hctxs inside a queue. We only mark restart for shared hctxs inside a queue and may cause io hung if there is no tag currently allocated by hctxs going to be marked restart. Wait on sbitmap_queue instead of mark restart for shared hctxs case to fix this. Fixes: 32bc15afed04 ("blk-mq: Facilitate a shared sbitmap per tagset") Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> 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 8bc6778454e10..b9e3b558367f1 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1831,7 +1831,8 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx, wait_queue_entry_t *wait; bool ret; - if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) { + if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) && + !(blk_mq_is_shared_tags(hctx->flags))) { blk_mq_sched_mark_restart_hctx(hctx); /* @@ -2101,7 +2102,8 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list, bool needs_restart; /* For non-shared tags, the RESTART check will suffice */ bool no_tag = prep == PREP_DISPATCH_NO_TAG && - (hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED); + ((hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) || + blk_mq_is_shared_tags(hctx->flags)); if (nr_budgets) blk_mq_release_budgets(q, list);