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Subject: Re: 5.14-rc failure to resume
From:   Jens Axboe <axboe@kernel.dk>
To:     LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Daniel Scally <djrscally@gmail.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
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Message-ID: <99068691-01ea-d2b5-3dd3-1a2852fe5723@kernel.dk>
Date:   Sat, 24 Jul 2021 13:43:54 -0600
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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.

-- 
Jens Axboe