linux-kernel - Re: [PATCH] blk-mq: clear active_queues before clearing BLK_MQ_F_TAG_QUEUE

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Message-ID: <198821c1-520c-4175-4c4e-ee092c271baa@kernel.dk>
Date:   Fri, 13 Aug 2021 08:01:53 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Yu Kuai <yukuai3@...wei.com>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com
Subject: Re: [PATCH] blk-mq: clear active_queues before clearing
 BLK_MQ_F_TAG_QUEUE_SHARED

On 7/31/21 12:21 AM, 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
> deleted.
> 
> Thus clear active_queues before BLK_MQ_F_TAG_QUEUE_SHARED is cleared.

Applied, thanks.

-- 
Jens Axboe