Re: [PATCH] blk-mq: clear active_queues before clearing BLK_MQ_F_TAG_QUEUE_SHARED

From: yukuai (C)
Date: Thu Aug 05 2021 - 21:47:36 EST

On 2021/07/31 14:21, Yu Kuai wrote:
We run a test that delete and recover devcies frequently(two devices on
the same host), and we found that 'active_queues' is super big after a
period of time.

If device a and device b share a tag set, and a is deleted, then
blk_mq_exit_queue() will clear BLK_MQ_F_TAG_QUEUE_SHARED because there
is only one queue that are using the tag set. However, if b is still
active, the active_queues of b might never be cleared even if b is

Thus clear active_queues before BLK_MQ_F_TAG_QUEUE_SHARED is cleared.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
block/blk-mq.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 2c4ac51e54eb..2fe396385a4a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2994,10 +2994,12 @@ static void queue_set_hctx_shared(struct request_queue *q, bool shared)
int i;
queue_for_each_hw_ctx(q, hctx, i) {
- if (shared)
+ if (shared) {
hctx->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
- else
+ } else {
+ blk_mq_tag_idle(hctx);
hctx->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
+ }