From: Jens Axboe <axboe@kernel.dk>
To: Paolo Valente <paolo.valente@linaro.org>, Mike Galbraith <efault@gmx.de>
Cc: Oleksandr Natalenko <oleksandr@natalenko.name>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH BUGFIX V3] block, bfq: add requeue-request hook
Date: Wed, 14 Feb 2018 08:19:07 -0700 [thread overview]
Message-ID: <0cdbafe7-fe13-51b4-4e86-e7453026508e@kernel.dk> (raw)
In-Reply-To: <07DA441B-C2E8-4F65-B674-11C87D2F084B@linaro.org>
On 2/14/18 1:56 AM, Paolo Valente wrote:
>
>
>> Il giorno 14 feb 2018, alle ore 08:15, Mike Galbraith <efault@gmx.de> ha scritto:
>>
>> On Wed, 2018-02-14 at 08:04 +0100, Mike Galbraith wrote:
>>>
>>> And _of course_, roughly two minutes later, IO stalled.
>>
>> P.S.
>>
>> crash> bt 19117
>> PID: 19117 TASK: ffff8803d2dcd280 CPU: 7 COMMAND: "kworker/7:2"
>> #0 [ffff8803f7207bb8] __schedule at ffffffff81595e18
>> #1 [ffff8803f7207c40] schedule at ffffffff81596422
>> #2 [ffff8803f7207c50] io_schedule at ffffffff8108a832
>> #3 [ffff8803f7207c60] blk_mq_get_tag at ffffffff8129cd1e
>> #4 [ffff8803f7207cc0] blk_mq_get_request at ffffffff812987cc
>> #5 [ffff8803f7207d00] blk_mq_alloc_request at ffffffff81298a9a
>> #6 [ffff8803f7207d38] blk_get_request_flags at ffffffff8128e674
>> #7 [ffff8803f7207d60] scsi_execute at ffffffffa0025b58 [scsi_mod]
>> #8 [ffff8803f7207d98] scsi_test_unit_ready at ffffffffa002611c [scsi_mod]
>> #9 [ffff8803f7207df8] sd_check_events at ffffffffa0212747 [sd_mod]
>> #10 [ffff8803f7207e20] disk_check_events at ffffffff812a0f85
>> #11 [ffff8803f7207e78] process_one_work at ffffffff81079867
>> #12 [ffff8803f7207eb8] worker_thread at ffffffff8107a127
>> #13 [ffff8803f7207f10] kthread at ffffffff8107ef48
>> #14 [ffff8803f7207f50] ret_from_fork at ffffffff816001a5
>> crash>
>
> This has evidently to do with tag pressure. I've looked for a way to
> easily reduce the number of tags online, so as to put your system in
> the bad spot deterministically. But at no avail. Does anyone know a
> way to do it?
The key here might be that it's not a regular file system request,
which I'm sure bfq probably handles differently. So it's possible
that you are slowly leaking those tags, and we end up in this
miserable situation after a while.
--
Jens Axboe
next prev parent reply other threads:[~2018-02-14 15:19 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-07 21:19 [PATCH BUGFIX V3] block, bfq: add requeue-request hook Paolo Valente
2018-02-07 22:18 ` Jens Axboe
2018-02-08 7:16 ` Paolo Valente
2018-02-08 7:16 ` Paolo Valente
2018-02-09 13:21 ` Oleksandr Natalenko
2018-02-09 17:17 ` Jens Axboe
2018-02-09 17:29 ` Mike Galbraith
2018-02-10 8:29 ` Oleksandr Natalenko
2018-02-10 8:29 ` Oleksandr Natalenko
2018-02-12 7:24 ` Paolo Valente
2018-02-12 7:24 ` Paolo Valente
2018-02-12 11:22 ` Mike Galbraith
2018-02-12 12:48 ` Oleksandr Natalenko
2018-02-13 5:02 ` Mike Galbraith
2018-02-13 5:46 ` Paolo Valente
2018-02-13 6:42 ` Mike Galbraith
2018-02-13 6:50 ` Mike Galbraith
2018-02-13 8:15 ` Paolo Valente
2018-02-13 14:30 ` Mike Galbraith
2018-02-14 5:58 ` Mike Galbraith
2018-02-14 7:04 ` Mike Galbraith
2018-02-14 7:15 ` Mike Galbraith
2018-02-14 8:56 ` Paolo Valente
2018-02-14 9:55 ` Oleksandr Natalenko
2018-02-14 13:25 ` Mike Galbraith
2018-02-14 15:19 ` Jens Axboe [this message]
2018-02-14 15:39 ` Paolo Valente
2018-02-14 15:44 ` Jens Axboe
2018-02-15 18:13 ` Paolo Valente
2018-02-16 5:39 ` Mike Galbraith
2018-02-16 7:16 ` Paolo Valente
2018-02-16 7:20 ` Paolo Valente
2018-02-17 5:30 ` Mike Galbraith
2018-02-17 5:33 ` Mike Galbraith
2018-02-19 5:34 ` Mike Galbraith
2018-02-19 6:05 ` Oleksandr Natalenko
2018-02-19 7:09 ` Mike Galbraith
2018-02-19 7:58 ` Mike Galbraith
2018-02-19 9:37 ` Paolo Valente
2018-02-19 13:18 ` Mike Galbraith
2018-02-17 5:39 ` Mike Galbraith
2018-02-26 19:48 ` Greg KH
2018-02-26 20:10 ` Oleksandr Natalenko
2018-02-26 20:18 ` Jens Axboe
2018-02-23 15:07 ` Ming Lei
2018-02-23 15:41 ` Paolo Valente
2018-02-23 15:41 ` Paolo Valente
2018-02-23 16:17 ` Ming Lei
2018-02-24 7:54 ` Paolo Valente
2018-02-24 7:54 ` Paolo Valente
2018-02-24 12:05 ` Ming Lei
2018-02-24 16:15 ` Paolo Valente
2018-02-24 16:15 ` Paolo Valente
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