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 6.1-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-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 74c0ea813123c41376fed91bc07c9ad0c8ab1c65
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 faffc64fe4ce8..fe0a3a882f465 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1799,7 +1799,8 @@ 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);
/*
@@ -2069,7 +2070,8 @@ 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);
