Re: [bisected] bfq regression on latest linux-block/for-next

From: Paolo Valente <paolo.valente@linaro.org>
To: Yi Zhang <yi.zhang@redhat.com>
Cc: linux-block <linux-block@vger.kernel.org>,
	Xiong Zhou <xzhou@redhat.com>, Li Wang <liwan@redhat.com>,
	Ming Lei <minlei@redhat.com>,
	Bruno Goncalves <bgoncalv@redhat.com>
Subject: Re: [bisected] bfq regression on latest linux-block/for-next
Date: Tue, 11 May 2021 19:10:22 +0200	[thread overview]
Message-ID: <AE809A3F-9AAA-4289-BED4-74F67361B71F@linaro.org> (raw)
In-Reply-To: <CAHj4cs_4jPzoZWcuio+jQig4GARVfMac9h=0TyYCiQYqXmXUyQ@mail.gmail.com>

> Il giorno 7 mag 2021, alle ore 10:30, Yi Zhang <yi.zhang@redhat.com> ha scritto:
> 
> On Mon, May 3, 2021 at 5:35 PM Paolo Valente <paolo.valente@linaro.org> wrote:
>> 
>> 
>> 
>>> Il giorno 20 apr 2021, alle ore 09:33, Paolo Valente <paolo.valente@linaro.org> ha scritto:
>>> 
>>> 
>>> 
>>>> Il giorno 20 apr 2021, alle ore 04:00, Yi Zhang <yi.zhang@redhat.com> ha scritto:
>>>> 
>>>> 
>>>> On Wed, Apr 7, 2021 at 11:15 PM Yi Zhang <yi.zhang@redhat.com> wrote:
>>>> 
>>>> 
>>>> On 4/2/21 9:39 PM, Paolo Valente wrote:
>>>>> 
>>>>>> Il giorno 1 apr 2021, alle ore 03:27, Yi Zhang <yi.zhang@redhat.com> ha scritto:
>>>>>> 
>>>>>> Hi
>>>>> Hi
>>>>> 
>>>>>> We reproduced this bfq regression[3] on ppc64le with blktests[2] on the latest linux-block/for-next branch, seems it was introduced with [1] from my bisecting, pls help check it. Let me know if you need any testing for it, thanks.
>>>>>> 
>>>>> Thanks for reporting this bug and finding the candidate offending commit. Could you try this test with my dev kernel, which might provide more information? The kernel is here:
>>>>> https://github.com/Algodev-github/bfq-mq
>>>>> 
>>>>> Alternatively, I could try to provide you with patches to instrument your kernel.
>>>> HI Paolo
>>>> I tried your dev kernel, but with no luck to reproduce it, could you
>>>> provide the debug patch based on latest linux-block/for-next?
>>>> 
>>>> Hi Paolo
>>>> This issue has been consistently reproduced with LTP/fstests/blktests on recent linux-block/for-next, do you have a chance to check it?
>>> 
>>> Hi Yi, all,
>>> I've been working hard to port my code-instrumentation layer to the kernel in for-next. I seem I finished the porting yesterday. I tested it but the system crashed. I'm going to analyze the oops. Maybe this freeze is caused by mistakes in this layer, maybe the instrumentation is already detecting a bug. In the first case, I'll fix the mistakes and try the tests suggested in this thread.
>>> 
>> 
>> Hi Yi, all,
>> I seem to have made it.  I've attached a patch series, which applies
>> on top of for-next, as it was when you reported this failure (i.e., on
>> top of 816e1d1c2f7d Merge branch 'for-5.13/io_uring' into for-next).
>> If patches are to be applied on top of a different HEAD, and they
>> don't apply cleanly, I'll take care of rebasing them.
>> 
>> Of course I've tried your test myself, but with no failure at all.
>> 
>> Looking forward to your feedback,
>> Paolo
>> 
> Hi Paolo
> 
> With the patch series, blktests nvme-tcp nvme/011 passed on
> linux-block/for-next, thanks.
> 

Great!

That series contained only one fix.  I do hope that it has been that
fix to eliminate the failure.

So I'm about to propose such a fix as an individual patch for
mainline.  Please test it if you can.

Thanks,
Paolo

> Thanks
> Yi