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From: Sagi Grimberg <sagi@grimberg.me>
To: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@kernel.org>, linux-nvme@lists.infradead.org
Subject: Re: [PATCH 1/2] nvme-tcp: fix controller reset hang during traffic
Date: Tue, 28 Jul 2020 08:57:24 -0700	[thread overview]
Message-ID: <8ef59b19-c2a4-df0f-4f41-e9779aff7334@grimberg.me> (raw)
In-Reply-To: <20200728104959.GA29442@lst.de>


>> commit fe35ec58f0d3 ("block: update hctx map when use multiple maps")
>> exposed an issue where we may hang trying to wait for queue freeze
>> during I/O. We call blk_mq_update_nr_hw_queues which in case of multiple
>> queue maps (which we have now for default/read/poll) is attempting to
>> freeze the queue. However we never started queue freeze when starting the
>> reset, which means that we have inflight pending requests that entered the
>> queue that we will not complete once the queue is quiesced.
>>
>> So start a freeze before we quiesce the queue, and unfreeze the queue
>> after we successfully connected the I/O queues (and make sure to call
>> blk_mq_update_nr_hw_queues only after we are sure that the queue was
>> already frozen).
>>
>> This follows to how the pci driver handles resets.
>>
>> Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
> 
> Applied to nvme-5.9.  I've also addeda fixes tag.

It doesn't fix a regression caused by this commit, but rather exposed
by this commit. I agree that its good to have it for stable.

Thanks

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      reply	other threads:[~2020-07-28 15:57 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-24 22:10 [PATCH 1/2] nvme-tcp: fix controller reset hang during traffic Sagi Grimberg
2020-07-24 22:10 ` [PATCH 2/2] nvme-rdma: " Sagi Grimberg
2020-07-28 10:49 ` [PATCH 1/2] nvme-tcp: " Christoph Hellwig
2020-07-28 15:57   ` Sagi Grimberg [this message]

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