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

yukuai (C)
2021-08-13T12:37:07Z

Hi, jens

Can you please consider to apply this patch.

By the way, sorry about the wrong email I replied.

Thanks
Kuai

On 2021/08/06 10:25, Ming Lei wrote:
> On Sat, Jul 31, 2021 at 02:21:30PM +0800, 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.
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> ---
>> 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;
>> + }
>> }
>> }
>
> Looks correct, the only remained queue in tagset has to be idled before
> clearing BLK_MQ_F_TAG_QUEUE_SHARED:
>
> Reviewed-by: Ming Lei <ming.lei@redhat.com>
>
>
>
> Thanks,
> Ming
>
> .
>