From: Sagi Grimberg <sagi@grimberg.me>
To: Chao Leng <lengchao@huawei.com>, Christoph Hellwig <hch@lst.de>,
Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org
Subject: Re: [PATCH 2/2] nvme-multipath: don't block on blk_queue_enter of the underlying device
Date: Tue, 23 Mar 2021 00:36:40 -0700 [thread overview]
Message-ID: <5d28226d-4619-74b6-1c73-c13ed57aa7ea@grimberg.me> (raw)
In-Reply-To: <31e7f7f4-55fa-6b0c-426d-7f7e7638ab4b@huawei.com>
> I check it again. I still think the below patch can avoid the bug.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5a6c35f9af416114588298aa7a90b15bbed15a41
I don't understand what you are saying...
>
> The process:
> 1.nvme_ns_head_submit_bio call srcu_read_lock(&head->srcu).
> 2.nvme_ns_head_submit_bio will add the bio to current->bio_list instead
> of waiting for the frozen queue.
Nothing guarantees that you have a bio_list active at any point in time,
in fact for a workload that submits one by one you will always drain
that list directly in the submission...
> 3.nvme_ns_head_submit_bio call srcu_read_unlock(&head->srcu, srcu_idx).
> So nvme_ns_head_submit_bio do not hold head->srcu long when the queue is
> frozen, can avoid deadlock.
>
> Sagi, suggest trying this patch.
The above reproduces with the patch applied on upstream nvme code.
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next prev parent reply other threads:[~2021-03-23 7:37 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 7:37 fix nvme-tcp and nvme-rdma controller reset hangs when using multipath Christoph Hellwig
2021-03-22 7:37 ` [PATCH 1/2] blk-mq: add a blk_mq_submit_bio_direct API Christoph Hellwig
2021-03-22 11:23 ` Hannes Reinecke
2021-03-22 15:30 ` Keith Busch
2021-03-22 7:37 ` [PATCH 2/2] nvme-multipath: don't block on blk_queue_enter of the underlying device Christoph Hellwig
2021-03-22 11:22 ` Hannes Reinecke
2021-03-22 15:31 ` Keith Busch
2021-03-23 2:57 ` Sagi Grimberg
2021-03-23 3:23 ` Sagi Grimberg
2021-03-23 7:04 ` Chao Leng
2021-03-23 7:36 ` Sagi Grimberg [this message]
2021-03-23 8:13 ` Chao Leng
2021-03-23 16:17 ` Christoph Hellwig
2021-03-23 16:15 ` Christoph Hellwig
2021-03-23 18:13 ` Sagi Grimberg
2021-03-23 18:22 ` Christoph Hellwig
2021-03-23 19:00 ` Sagi Grimberg
2021-03-23 19:01 ` Christoph Hellwig
2021-03-23 19:10 ` Sagi Grimberg
2021-03-23 7:28 ` Hannes Reinecke
2021-03-23 7:31 ` Sagi Grimberg
2021-03-23 8:36 ` Hannes Reinecke
2021-03-23 14:53 ` Keith Busch
2021-03-23 16:19 ` Christoph Hellwig
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