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Subject: Re: 5.14-rc failure to resume
To:     Andy Shevchenko <andy.shevchenko@gmail.com>,
        Jens Axboe <axboe@kernel.dk>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
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 <CAHp75VeJwuUmpn15iS4NgzO9Qh=O5ve9i62xCzQEJ=5Mm11N3g@mail.gmail.com>
From:   Daniel Scally <djrscally@gmail.com>
Message-ID: <85cd7b22-b437-2c47-d532-0a167339df48@gmail.com>
Date:   Sat, 24 Jul 2021 22:21:04 +0100
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On 24/07/2021 22:15, Andy Shevchenko wrote:
> On Sat, Jul 24, 2021 at 11:26 PM Jens Axboe <axboe@kernel.dk> wrote:
>>
>> On 7/24/21 2:05 PM, Andy Shevchenko wrote:
>>> On Sat, Jul 24, 2021 at 10:43 PM Jens Axboe <axboe@kernel.dk> wrote:
>>>> On 7/24/21 11:56 AM, Jens Axboe wrote:
>>>>> On 7/24/21 9:57 AM, Jens Axboe wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I ran into this when doing the last bit of testing on pending changes
>>>>>> for this release on the laptop. Outside of running testing on these
>>>>>> changes, I always build and boot current -git and my changes on my
>>>>>> laptop as well.
>>>>>>
>>>>>> 5.14-rc1 + changes works fine, current -git and changes fail to resume
>>>>>> every single time. I just get a black screen. Tip of tree before merging
>>>>>> fixes is:
>>>>>>
>>>>>> commit 704f4cba43d4ed31ef4beb422313f1263d87bc55 (origin/master, origin/HEAD, master)
>>>>>> Merge: 05daae0fb033 0077a5008272
>>>>>> Author: Linus Torvalds <torvalds@linux-foundation.org>
>>>>>> Date:   Fri Jul 23 11:30:12 2021 -0700
>>>>>>
>>>>>>     Merge tag 'ceph-for-5.14-rc3' of git://github.com/ceph/ceph-client
>>>>>>
>>>>>> Since bisection takes forever on the laptop (gen7 x1 carbon), I
>>>>>> opportunistically reverted some of the most recent git pulls:
>>>>>>
>>>>>> - ec6badfbe1cde0eb2bec4a0b8f6e738171156b5b (acpi changes)
>>>>>> - 1d597682d3e669ec7021aa33d088ed3d136a5149 (driver-core changes)
>>>>>> - 74738c556db6c7f780a8b98340937e55b72c896a (usb changes)
>>>>>> - e7562a00c1f54116f5a058e7e3ddd500188f60b2 (sound changes)
>>>>>> - 8baef6386baaefb776bdd09b5c7630cf057c51c6 (drm changes)
>>>>>>
>>>>>> as they could potentially be involved, but even with all of those
>>>>>> reverted it still won't resume.
>>>>>>
>>>>>> Sending this out in case someone has already reported this and I just
>>>>>> couldn't find it. If this is a new/unknown issues, I'll go ahead and
>>>>>> bisect it.
>>>>>
>>>>> Ran a bisect, and it pinpoints:
>>>>>
>>>>> 71f6428332844f38c7cb10461d9f29e9c9b983a0 is the first bad commit
>>>>> commit 71f6428332844f38c7cb10461d9f29e9c9b983a0
>>>>> Author: Andy Shevchenko <andy.shevchenko@gmail.com>
>>>>> Date:   Mon Jul 12 21:21:21 2021 +0300
>>>>>
>>>>>     ACPI: utils: Fix reference counting in for_each_acpi_dev_match()
>>>>>
>>>>> which seems odd, as it worked for me with the acpi changes reverted. It
>>>>> could be that it _sometimes_ works with that commit, not sure. Adding
>>>>> relevant folks to the CC.
>>>>>
>>>>> I'm going to revert this on top of current master and run with that
>>>>> and see if it does 10 successful resumes.
>>>>
>>>> This does appear to be the culprit. With it reverted on top of current
>>>> master (and with the block and io_uring changes pulled in too), the
>>>> kernel survives many resumes without issue.
>>>
>>> If I read correctly it seems at one of the local rebase I might have
>>> missed something.
>>>
>>> Can you replace sensor->adev with adev here
>>>
>>> https://elixir.bootlin.com/linux/v5.14-rc2/source/drivers/media/pci/intel/ipu3/cio2-bridge.c#L231
>>>
>>> and retest?
>>
>> Tried that, doesn't work unfortunately. Hung on first resume, just like
>> current -git with that single line edit.
> 
> So, does it work along with the acpi_dev_put() converted to be
> 
>   if (adev)
>     put_device(&adev->dev);
> 
> ?

For me; yes. I replicated the issue, and adding the if (adev) guard and
the previous change you mentioned clears it again.