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From: Christoph Hellwig <hch@lst.de>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	Damien Le Moal <dlemoal@kernel.org>,
	linux-block@vger.kernel.org
Subject: Re: [PATCH 4/7] blk-mq: use the I/O scheduler for writes from the flush state machine
Date: Thu, 25 May 2023 10:14:37 +0200	[thread overview]
Message-ID: <20230525081437.GA22420@lst.de> (raw)
In-Reply-To: <f7a7595f-6fd6-5fdf-4c64-b4fff367239c@acm.org>

On Wed, May 24, 2023 at 11:07:41AM -0700, Bart Van Assche wrote:
> On 5/23/23 22:53, Christoph Hellwig wrote:
>> I turns out this causes some kind of hang I haven't been able to
>> debug yet in blktests' hotplug test.   Can you drop this and the
>> subsequent patches for now?
>
> Hi Christoph,
>
> I haven't seen this hang in my tests. If you can tell me how to run 
> blktests I can help with root-causing this issue. This is how I run 
> blktests:

This is a simple ./check run with this config, and most importantly
modular scsi_debug (which is not my usual config, othewise I would
have noticed it earlier):

----- snip -----
TEST_DEVS=(/dev/vdb)
nvme_trtype=tcp
----- snip -----

It hangs in block/001 when probing scsi_debug:

[  242.790601] INFO: task modprobe:3702 blocked for more than 120 seconds.
[  242.791572]       Not tainted 6.4.0-rc2+ #1179
[  242.792201] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
message.
[  242.793387] task:modprobe        state:D stack:0     pid:3702  ppid:3686
flags:0x00004002
[  242.794724] Call Trace:
[  242.795121]  <TASK>
[  242.795465]  __schedule+0x307/0x840
[  242.796053]  ? call_usermodehelper_exec+0xee/0x180
[  242.796812]  schedule+0x57/0xa0
[  242.797316]  async_synchronize_full+0xa0/0x130
[  242.798029]  ? destroy_sched_domains_rcu+0x20/0x20
[  242.798803]  do_init_module+0x19f/0x200
[  242.799657]  __do_sys_finit_module+0x9e/0xf0
[  242.800324]  do_syscall_64+0x34/0x80
[  242.800879]  entry_SYSCALL_64_after_hwframe+0x63/0xcd


  reply	other threads:[~2023-05-25  8:14 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-19  4:40 less special casing for flush requests v2 Christoph Hellwig
2023-05-19  4:40 ` [PATCH 1/7] blk-mq: factor out a blk_rq_init_flush helper Christoph Hellwig
2023-05-19 18:54   ` Bart Van Assche
2023-05-19  4:40 ` [PATCH 2/7] blk-mq: reflow blk_insert_flush Christoph Hellwig
2023-05-19 19:38   ` Bart Van Assche
2023-05-19  4:40 ` [PATCH 3/7] blk-mq: defer to the normal submission path for non-flush flush commands Christoph Hellwig
2023-05-19  4:40 ` [PATCH 4/7] blk-mq: use the I/O scheduler for writes from the flush state machine Christoph Hellwig
2023-05-19 19:44   ` Bart Van Assche
2023-05-24  5:53   ` Christoph Hellwig
2023-05-24 18:07     ` Bart Van Assche
2023-05-25  8:14       ` Christoph Hellwig [this message]
2023-05-28 20:50     ` Bart Van Assche
2023-05-30 14:55       ` Christoph Hellwig
2023-05-31 13:34         ` Bart Van Assche
2023-05-31 15:00           ` Christoph Hellwig
2023-05-19  4:40 ` [PATCH 5/7] blk-mq: defer to the normal submission path for post-flush requests Christoph Hellwig
2023-05-19 19:42   ` Bart Van Assche
2023-05-19  4:40 ` [PATCH 6/7] blk-mq: do not do head insertions post-pre-flush commands Christoph Hellwig
2023-05-19  4:40 ` [PATCH 7/7] blk-mq: don't use the requeue list to queue flush commands Christoph Hellwig
2023-05-19 19:55   ` Bart Van Assche
2023-05-20  4:56     ` Christoph Hellwig
2023-05-21 14:06       ` Bart Van Assche
2023-05-20  1:53 ` less special casing for flush requests v2 Jens Axboe

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