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Subject: Re: bug in tag handling in blk-mq?
From: Jens Axboe <axboe@kernel.dk>
To: Mike Galbraith <efault@gmx.de>,
        Paolo Valente <paolo.valente@linaro.org>
Cc: Christoph Hellwig <hch@lst.de>,
        linux-block <linux-block@vger.kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Oleksandr Natalenko <oleksandr@natalenko.name>
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Date: Tue, 8 May 2018 15:19:23 -0600
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On 5/8/18 2:37 PM, Jens Axboe wrote:
> On 5/8/18 10:42 AM, Mike Galbraith wrote:
>> On Tue, 2018-05-08 at 08:55 -0600, Jens Axboe wrote:
>>>
>>> All the block debug files are empty...
>>
>> Sigh.  Take 2, this time cat debug files, having turned block tracing
>> off before doing anything else (so trace bits in dmesg.txt should end
>> AT the stall).
> 
> OK, that's better. What I see from the traces:
> 
> - You have regular IO and some non-fs IO (from scsi_execute()). This mix
>   may be key.
> 
> - sdd has nothing pending, yet has 6 active waitqueues.
> 
> I'm going to see if I can reproduce this. Paolo, what kind of attempts
> to reproduce this have you done?

No luck so far. Out of the patches you referenced, I can only find the
shallow depth change, since that's in the parent of this email. Can
you send those as well?

Perhaps also expand a bit on exactly what you are running. File system,
mount options, etc.

-- 
Jens Axboe