From: Chao Leng <lengchao@huawei.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>, Keith Busch <kbusch@kernel.org>,
<linux-nvme@lists.infradead.org>,
Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Subject: Re: [PATCH 0/3 rfc] Fix nvme-tcp and nvme-rdma controller reset hangs
Date: Wed, 17 Mar 2021 15:59:55 +0800 [thread overview]
Message-ID: <2e391aae-58c7-b8f7-1a9e-d7ad5bb3f8f3@huawei.com> (raw)
In-Reply-To: <20210317065910.GC14498@lst.de>
On 2021/3/17 14:59, Christoph Hellwig wrote:
> On Wed, Mar 17, 2021 at 10:55:57AM +0800, Chao Leng wrote:
>>>> Will it work if nvme mpath used request NOWAIT flag for its submit_bio()
>>>> call, and add the bio to the requeue_list if blk_queue_enter() fails? I
>>>> think that looks like another way to resolve the deadlock, but we need
>>>> the block layer to return a failed status to the original caller.
>
> Yes, I think BLK_MQ_REQ_NOWAIT makes total sense here. dm-mpath also
> uses it for its request allocation for similar reasons.
>
>>>
>>> But who would kick the requeue list? and that would make near-tag-exhaust performance stink...
>
> The multipath code would have to kick the list. We could also try to
> split into two flags, one that affects blk_queue_enter and one that
> affects the tag allocation.
>
>> moving nvme_start_freeze from nvme_rdma_teardown_io_queues to nvme_rdma_configure_io_queues can fix it.
>> It can also avoid I/O hang long time if reconnection failed.
>
> Can you explain how we'd still ensure that no new commands get queued
> during teardown using that scheme?
1. tear down will cancel all inflight requests, and then multipath will clear the path.
2. and then we may freeze the controler.
3. nvme_ns_head_submit_bio can not find the reconnection controller as valid path, so it is safe.
> .
>
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next prev parent reply other threads:[~2021-03-17 8:00 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 22:27 [PATCH 0/3 rfc] Fix nvme-tcp and nvme-rdma controller reset hangs Sagi Grimberg
2021-03-15 22:27 ` [PATCH 1/3] nvme: introduce nvme_ctrl_is_mpath helper Sagi Grimberg
2021-03-15 22:27 ` [PATCH 2/3] nvme-tcp: fix possible hang when trying to set a live path during I/O Sagi Grimberg
2021-03-15 22:27 ` [PATCH 3/3] nvme-rdma: " Sagi Grimberg
2021-03-16 3:24 ` [PATCH 0/3 rfc] Fix nvme-tcp and nvme-rdma controller reset hangs Chao Leng
2021-03-16 5:04 ` Sagi Grimberg
2021-03-16 6:18 ` Chao Leng
2021-03-16 6:25 ` Sagi Grimberg
2021-03-16 20:07 ` Sagi Grimberg
2021-03-16 20:42 ` Keith Busch
2021-03-16 23:51 ` Sagi Grimberg
2021-03-17 2:55 ` Chao Leng
2021-03-17 6:59 ` Christoph Hellwig
2021-03-17 7:59 ` Chao Leng [this message]
2021-03-17 18:43 ` Sagi Grimberg
2021-03-18 1:51 ` Chao Leng
2021-03-18 4:45 ` Christoph Hellwig
2021-03-18 18:46 ` Sagi Grimberg
2021-03-18 19:16 ` Keith Busch
2021-03-18 19:31 ` Sagi Grimberg
2021-03-18 21:52 ` Keith Busch
2021-03-18 22:45 ` Sagi Grimberg
2021-03-19 14:05 ` Christoph Hellwig
2021-03-19 17:28 ` Christoph Hellwig
2021-03-19 19:07 ` Keith Busch
2021-03-19 19:34 ` Sagi Grimberg
2021-03-20 6:11 ` Christoph Hellwig
2021-03-21 6:49 ` Sagi Grimberg
2021-03-22 6:34 ` Christoph Hellwig
2021-03-17 8:16 ` Sagi Grimberg
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