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

[yukuai (C)]

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@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;
> > +		}
> >   	}
> >   }
>
> 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@xxxxxxxxxx>
>
>
>
> Thanks,
> Ming
>
> .