Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH] blk-mq: clear active_queues before clearing
 BLK_MQ_F_TAG_QUEUE_SHARED
To:     Ming Lei <ming.lei@redhat.com>
CC:     <axboe@kernel.dk>, <linux-block@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <yi.zhang@huawei.com>
References: <20210731062130.1533893-1-yukuai3@huawei.com>
 <YQydfkffPhBEFpwB@T590>
From:   "yukuai (C)" <yukuai3@huawei.com>
Message-ID: <0f8e7e8c-9c4d-7b88-a967-c54cbbe038c8@huawei.com>
Date:   Fri, 13 Aug 2021 20:36:44 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <YQydfkffPhBEFpwB@T590>
Content-Type: text/plain; charset="gbk"; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

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
> 
> .
>