From: Bart Van Assche <bvanassche@acm.org>
To: Mohamed Khalfella <mkhalfella@purestorage.com>
Cc: Chaitanya Kulkarni <kch@nvidia.com>,
Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Keith Busch <kbusch@kernel.org>, Sagi Grimberg <sagi@grimberg.me>,
Casey Chen <cachen@purestorage.com>,
Yuanyuan Zhong <yzhong@purestorage.com>,
Hannes Reinecke <hare@suse.de>, Ming Lei <ming.lei@redhat.com>,
Waiman Long <llong@redhat.com>, Hillf Danton <hdanton@sina.com>,
linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock
Date: Thu, 4 Dec 2025 10:24:03 -1000 [thread overview]
Message-ID: <6994b9a7-ef2b-42f3-9e72-7489a56f8f8e@acm.org> (raw)
In-Reply-To: <20251204195759.GC337106-mkhalfella@purestorage.com>
On 12/4/25 9:57 AM, Mohamed Khalfella wrote:
> I do not see how running this code in another thread will solve the
> problem.
blk_mq_freeze_queue_wait() waits forever because nvme_timeout() waits
for blk_mq_freeze_queue_wait() to finish. Hence, the deadlock can be
solved by removing the blk_mq_quiesce_tagset() call from nvme_timeout()
and by failing I/O from inside nvme_timeout(). If nvme_timeout() fails
I/O and does not call blk_mq_quiesce_tagset() then the
blk_mq_freeze_queue_wait() call will finish instead of triggering a
deadlock. However, I do not know whether this proposal seems acceptable
to the NVMe maintainers.
Bart.
next prev parent reply other threads:[~2025-12-04 20:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-04 18:11 [PATCH 0/1] Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock Mohamed Khalfella
2025-12-04 18:11 ` [PATCH 1/1] block: " Mohamed Khalfella
2025-12-04 18:22 ` Bart Van Assche
2025-12-04 18:42 ` Mohamed Khalfella
2025-12-04 19:06 ` Bart Van Assche
2025-12-04 19:15 ` Mohamed Khalfella
2025-12-04 19:31 ` Bart Van Assche
2025-12-04 19:57 ` Mohamed Khalfella
2025-12-04 20:24 ` Bart Van Assche [this message]
2025-12-04 21:26 ` Keith Busch
2025-12-04 23:22 ` Bart Van Assche
2025-12-05 1:32 ` Keith Busch
2025-12-05 2:52 ` Bart Van Assche
2025-12-05 16:39 ` Mohamed Khalfella
2025-12-05 18:11 ` Keith Busch
2025-12-08 19:22 ` Bart Van Assche
2025-12-04 19:02 ` Mohamed Khalfella
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