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From: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	Damien Le Moal <Damien.LeMoal@wdc.com>,
	Keith Busch <Keith.Busch@wdc.com>
Subject: Re: [PATCH V2 3/3] blk-mq: update hctx->nr_active in blk_mq_end_request_batch()
Date: Tue, 2 Nov 2021 22:43:53 +0000	[thread overview]
Message-ID: <20211102224352.sv5fihsfpkqjghgl@shindev> (raw)
In-Reply-To: <20211102153619.3627505-4-ming.lei@redhat.com>

On Nov 02, 2021 / 23:36, Ming Lei wrote:
> In case of shared tags and none io sched, batched completion still may
> be run into, and hctx->nr_active is accounted when getting driver tag,
> so it has to be updated in blk_mq_end_request_batch().
> 
> Otherwise, hctx->nr_active may become same with queue depth, then
> hctx_may_queue() always return false, then io hang is caused.
> 
> Fixes the issue by updating the counter in batched way.
> 
> Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> Fixes: f794f3351f26 ("block: add support for blk_mq_end_request_batch()")
> Signed-off-by: Ming Lei <ming.lei@redhat.com>

Ming, thank you very much. I have confirmed that the blktests block/005 hang
disappears using NVMe devices with two namespaces.

Though this patch is already queued up to for-5.16/block, in case it is still
meaningful:

Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>

-- 
Best Regards,
Shin'ichiro Kawasaki

  reply	other threads:[~2021-11-02 22:43 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-02 15:36 [PATCH V2 0/3] blk-mq: misc fixes Ming Lei
2021-11-02 15:36 ` [PATCH V2 1/3] blk-mq: only try to run plug merge if request has same queue with incoming bio Ming Lei
2021-11-02 15:36 ` [PATCH V2 2/3] blk-mq: add RQF_ELV debug entry Ming Lei
2021-11-02 15:36 ` [PATCH V2 3/3] blk-mq: update hctx->nr_active in blk_mq_end_request_batch() Ming Lei
2021-11-02 22:43   ` Shinichiro Kawasaki [this message]
2021-11-02 22:44     ` Jens Axboe
2021-11-02 16:00 ` [PATCH V2 0/3] blk-mq: misc fixes Jens Axboe

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