Re: [PATCH] Revert "blk-mq: issue directly if hw queue isn't busy in case of 'none'"

[Jens Axboe]

On 8/29/18 12:15 AM, Ulf Hansson wrote:
> On 28 August 2018 at 21:11, Hunter, Adrian <adrian.hunter@xxxxxxxxx> wrote:
>>> -----Original Message-----
>>> From: Jens Axboe [mailto:axboe@xxxxxxxxx]
>>> Sent: Tuesday, August 28, 2018 8:12 PM
>>> To: Ian W MORRISON <ianwmorrison@xxxxxxxxx>
>>> Cc: linux-block@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
>>> kashyap.desai@xxxxxxxxxxxx; loberman@xxxxxxxxxx; osandov@xxxxxx;
>>> hch@xxxxxx; bart.vanassche@xxxxxxx; hare@xxxxxxx;
>>> ming.lei@xxxxxxxxxx; Hunter, Adrian <adrian.hunter@xxxxxxxxx>
>>> Subject: Re: [PATCH] Revert "blk-mq: issue directly if hw queue isn't busy in
>>> case of 'none'"
>>>
>>> On 8/28/18 11:01 AM, Ian W MORRISON wrote:
>>>> On Wed, 29 Aug 2018 at 02:13, Jens Axboe <axboe@xxxxxxxxx> wrote:
>>>>>
>>>>> On 8/28/18 10:10 AM, Ian W MORRISON wrote:
>>>>>> On Wed, 29 Aug 2018 at 02:09, Jens Axboe <axboe@xxxxxxxxx> wrote:
>>>>>>>
>>>>>>> On 8/28/18 10:07 AM, Ian W MORRISON wrote:
>>>>>>>> On Wed, 29 Aug 2018 at 01:48, Jens Axboe <axboe@xxxxxxxxx>
>>> wrote:
>>>>>>>>>
>>>>>>>>> On 8/28/18 9:47 AM, Ian W MORRISON wrote:
>>>>>>>>>> Kernel oops when booting on Bay and Cherry Trail devices such as
>>>>>>>>>> Intel Compute Stick. Bisected as:
>>>>>>>>>>
>>>>>>>>>> commit 6ce3dd6eec11 ("blk-mq: issue directly if hw queue isn't
>>>>>>>>>> busy in case of 'none'")
>>>>>>>>>>
>>>>>>>>>> This patch reverts the above commit.
>>>>>>>>>
>>>>>>>>> Did I miss the posting of that oops? Just curious where this is
>>>>>>>>> going wrong. Not adverse to reverting, but I'd like to try to
>>>>>>>>> understand the issue first.
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Jens Axboe
>>>>>>>>>
>>>>>>>>
>>>>>>>> I've not been able to capture it however manually transcribing
>>>>>>>> what is on the screen:
>>>>>>>>
>>>>>>>> mmc0: Got data interrupt 0x00000002 even though no data operation
>>>>>>>>
>>>>>>>> followed by:
>>>>>>>>
>>>>>>>> mmc0: sdhci: ============= SDHCI REGISTER DUMP
>>> ==============
>>>>>>>>
>>>>>>>> Do you want any specific register value or should I transcribe
>>>>>>>> each (as I am working from an image taken at boot)?
>>>>>>>
>>>>>>> Just take a picture of the screen, that should be good enough.
>>>>>>>
>>>>>>> --
>>>>>>> Jens Axboe
>>>>>>>
>>>>>>
>>>>>> Attached as requested.
>>>>>
>>>>> Can you see if this patch helps?
>>>>>
>>>>> https://marc.info/?l=linux-mmc&m=153485326025301&w=2
>>>>>
>>>>> --
>>>>> Jens Axboe
>>>>>
>>>>
>>>> I confirm that the above patch works with commit 6ce3dd6eec11 and
>>>> removes the need for reverting it on eMMC based devices.
>>>>
>>>> Tested on Bay Trail, Cherry Trail (both now working) and Kaby Lake
>>>> (not affected) devices.
>>>
>>> Great, thanks for testing. Adrian, when is this going upstream?
>>
>> It is in Ulf's fixes branch, so most likely v4.19-rc2 .  Then to stable in due course.
>>
>>         https://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc.git/commit/?h=fixes&id=26caddf274cf1e89fd4ce44ab2b8dbc7a7f97681
> 
> Yep, correct!
> 
> As I told someone before, I am deliberately holding on to fixes a
> little longer that before, to extend the test coverage a bit.
> 
> If someone wants to test the latest rc with fixes, one could instead
> try the pending-fixes branch in Stephen Rothwell's linux-next tree.

With all due respect, you should expedite this one so we're not
wasting peoples time bisecting it again and again. I didn't even
know about a pending-fixes branch in the linux-next tree, so I
doubt most users will.

-- 
Jens Axboe