From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
Christoph Hellwig <hch@lst.de>, Qian Cai <cai@redhat.com>,
Sumit Saxena <sumit.saxena@broadcom.com>,
John Garry <john.garry@huawei.com>,
Kashyap Desai <kashyap.desai@broadcom.com>,
Bart Van Assche <bvanassche@acm.org>,
Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH 1/3] blk-mq: add new API of blk_mq_hctx_set_fq_lock_class
Date: Mon, 16 Nov 2020 18:26:58 +0100 [thread overview]
Message-ID: <20201116172658.GJ22007@lst.de> (raw)
In-Reply-To: <20201112075526.947079-2-ming.lei@redhat.com>
On Thu, Nov 12, 2020 at 03:55:24PM +0800, Ming Lei wrote:
> flush_end_io() may be called recursively from some driver, such as
> nvme-loop, so lockdep may complain 'possible recursive locking'.
> Commit b3c6a5997541("block: Fix a lockdep complaint triggered by
> request queue flushing") tried to address this issue by assigning
> dynamically allocated per-flush-queue lock class. This solution
> adds synchronize_rcu() for each hctx's release handler, and causes
> horrible SCSI MQ probe delay(more than half an hour on megaraid sas).
>
> Add new API of blk_mq_hctx_set_fq_lock_class() for these drivers, so
> we just need to use driver specific lock class for avoiding the
> lockdep warning of 'possible recursive locking'.
I'd turn this into an inline function to avoid the (although very
minimal) cost when LOCKDEP is not enabled.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
Bart Van Assche <bvanassche@acm.org>, Qian Cai <cai@redhat.com>,
John Garry <john.garry@huawei.com>,
linux-nvme@lists.infradead.org,
Kashyap Desai <kashyap.desai@broadcom.com>,
linux-block@vger.kernel.org,
Sumit Saxena <sumit.saxena@broadcom.com>,
Hannes Reinecke <hare@suse.de>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 1/3] blk-mq: add new API of blk_mq_hctx_set_fq_lock_class
Date: Mon, 16 Nov 2020 18:26:58 +0100 [thread overview]
Message-ID: <20201116172658.GJ22007@lst.de> (raw)
In-Reply-To: <20201112075526.947079-2-ming.lei@redhat.com>
On Thu, Nov 12, 2020 at 03:55:24PM +0800, Ming Lei wrote:
> flush_end_io() may be called recursively from some driver, such as
> nvme-loop, so lockdep may complain 'possible recursive locking'.
> Commit b3c6a5997541("block: Fix a lockdep complaint triggered by
> request queue flushing") tried to address this issue by assigning
> dynamically allocated per-flush-queue lock class. This solution
> adds synchronize_rcu() for each hctx's release handler, and causes
> horrible SCSI MQ probe delay(more than half an hour on megaraid sas).
>
> Add new API of blk_mq_hctx_set_fq_lock_class() for these drivers, so
> we just need to use driver specific lock class for avoiding the
> lockdep warning of 'possible recursive locking'.
I'd turn this into an inline function to avoid the (although very
minimal) cost when LOCKDEP is not enabled.
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next prev parent reply other threads:[~2020-11-16 17:27 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 7:55 [PATCH 0/3] blk-mq/nvme-loop: use nvme-loop's lock class for addressing lockdep false positive warning Ming Lei
2020-11-12 7:55 ` Ming Lei
2020-11-12 7:55 ` [PATCH 1/3] blk-mq: add new API of blk_mq_hctx_set_fq_lock_class Ming Lei
2020-11-12 7:55 ` Ming Lei
2020-11-16 17:26 ` Christoph Hellwig [this message]
2020-11-16 17:26 ` Christoph Hellwig
2020-11-17 1:04 ` Ming Lei
2020-11-17 1:04 ` Ming Lei
2020-11-17 1:16 ` Ming Lei
2020-11-17 1:16 ` Ming Lei
2020-11-17 6:46 ` Kashyap Desai
2020-11-17 6:46 ` Kashyap Desai
2020-11-12 7:55 ` [PATCH 2/3] nvme-loop: use blk_mq_hctx_set_fq_lock_class to set loop's lock class Ming Lei
2020-11-12 7:55 ` Ming Lei
2020-11-16 17:27 ` Christoph Hellwig
2020-11-16 17:27 ` Christoph Hellwig
2020-11-12 7:55 ` [PATCH 3/3] Revert "block: Fix a lockdep complaint triggered by request queue flushing" Ming Lei
2020-11-12 7:55 ` Ming Lei
2020-11-12 15:12 ` Bart Van Assche
2020-11-12 15:12 ` Bart Van Assche
2020-11-12 15:29 ` Bart Van Assche
2020-11-12 15:29 ` Bart Van Assche
2020-11-13 1:11 ` Ming Lei
2020-11-13 1:11 ` Ming Lei
2020-11-13 1:27 ` [PATCH V2 " Ming Lei
2020-11-13 1:27 ` Ming Lei
2020-11-16 17:27 ` Christoph Hellwig
2020-11-16 17:27 ` Christoph Hellwig
2020-11-25 1:31 ` [PATCH 0/3] blk-mq/nvme-loop: use nvme-loop's lock class for addressing lockdep false positive warning Ming Lei
2020-11-25 1:31 ` Ming Lei
2020-11-30 2:36 ` Ming Lei
2020-11-30 2:36 ` Ming Lei
2020-12-02 19:07 ` Qian Cai
2020-12-02 19:07 ` Qian Cai
2020-12-03 0:50 ` Ming Lei
2020-12-03 0:50 ` Ming Lei
2020-12-03 1:23 ` Qian Cai
2020-12-03 1:23 ` Qian Cai
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