From: Jens Axboe <axboe@kernel.dk>
To: Keith Busch <keith.busch@intel.com>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>, Ming Lei <ming.lei@redhat.com>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: WARNING: CPU: 2 PID: 207 at drivers/nvme/host/core.c:527 nvme_setup_cmd+0x3d3
Date: Tue, 30 Jan 2018 13:32:25 -0700 [thread overview]
Message-ID: <d09416a0-e9c8-a921-26f4-2b9da559da90@kernel.dk> (raw)
In-Reply-To: <20180130203011.GE27205@localhost.localdomain>
On 1/30/18 1:30 PM, Keith Busch wrote:
> On Tue, Jan 30, 2018 at 08:57:49AM -0700, Jens Axboe wrote:
>>
>> Looking at the disassembly, 'n' is 2 and 'segments' is 0xffff.
>
> Is this still a problem if you don't use an IO scheduler? With deadline,
> I'm not finding any path to bio_attempt_discard_merge which is where the
> nr_phys_segments is supposed to get it set to 2. Not sure how it could
> becmoe 0xffff, though.
blk_mq_make_request() -> blk_mq_sched_bio_merge() -> __blk_mq_sched_bio_merge()
-> blk_mq_attempt_merge() -> bio_attempt_discard_merge()
Doesn't matter what IO scheduler you use.
I don't know if it triggers without a scheduler. I've been running this code
continually on the laptop (always do), and haven't seen it before today.
--
Jens Axboe
next prev parent reply other threads:[~2018-01-30 20:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-30 15:41 WARNING: CPU: 2 PID: 207 at drivers/nvme/host/core.c:527 nvme_setup_cmd+0x3d3 Jens Axboe
2018-01-30 15:57 ` Jens Axboe
2018-01-30 20:30 ` Keith Busch
2018-01-30 20:32 ` Jens Axboe [this message]
2018-01-30 20:49 ` Keith Busch
2018-01-30 20:55 ` Jens Axboe
2018-01-31 4:25 ` jianchao.wang
2018-01-31 15:29 ` Jens Axboe
2018-01-31 23:33 ` Keith Busch
2018-02-01 3:03 ` Jens Axboe
2018-02-01 3:03 ` jianchao.wang
2018-02-01 3:07 ` Jens Axboe
2018-02-01 3:33 ` jianchao.wang
2018-02-01 3:35 ` Jens Axboe
2018-02-01 4:56 ` Keith Busch
2018-02-01 15:26 ` Jens Axboe
2018-02-01 17:58 ` Jens Axboe
2018-02-01 18:12 ` Keith Busch
2018-02-01 19:52 ` Keith Busch
2018-02-01 20:55 ` Jens Axboe
2018-02-01 18:01 ` Keith Busch
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