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Subject: Re: Bug: d0e936adbd22 crashes at boot
To:     Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Len Brown <lenb@kernel.org>, linux-pm@vger.kernel.org
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 <d6bf08cbfd9f29ddb8cf29f522d68efc5c676624.camel@linux.intel.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <903f2e71-983f-39b8-dd0b-d697616ab63e@kernel.dk>
Date:   Fri, 3 Sep 2021 14:41:23 -0600
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On 9/3/21 12:00 PM, Srinivas Pandruvada wrote:
> Hi Axobe,
> 
> On Fri, 2021-09-03 at 09:00 -0600, Jens Axboe wrote:
>> On 9/3/21 8:38 AM, Srinivas Pandruvada wrote:
>>> On Fri, 2021-09-03 at 08:15 -0600, Jens Axboe wrote:
>>>> On 9/3/21 8:13 AM, Srinivas Pandruvada wrote:
>>>>> Hi Axboe,
>>>>>
>>>>> Thanks for reporting.
>>>>> On Fri, 2021-09-03 at 07:36 -0600, Jens Axboe wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Booting Linus's tree causes a crash on my laptop, an x1 gen9.
>>>>>> This
>>>>>> was
>>>>>> a bit
>>>>>> difficult to pin down as it crashes before the display is up,
>>>>>> but I
>>>>>> managed
>>>>>> to narrow it down to:
>>>>>>
>>>>>> commit d0e936adbd2250cb03f2e840c6651d18edc22ace
>>>>>> Author: Srinivas Pandruvada < 
>>>>>> srinivas.pandruvada@linux.intel.com>
>>>>>> Date:   Thu Aug 19 19:40:06 2021 -0700
>>>>>>
>>>>>>     cpufreq: intel_pstate: Process HWP Guaranteed change
>>>>>> notification
>>>>>>
>>>>>> which crashes with a NULL pointer deref in
>>>>>> notify_hwp_interrupt() -
>>>>>>>
>>>>>> queue_delayed_work_on().
>>>>>>
>>>>>> Reverting this change makes the laptop boot fine again.
>>>>>>
>>>>> Does this change fixes your issue?
>>>>
>>>> I would assume so, as it's crashing on cpudata == NULL :-)
>>>>
>>>> But why is it NULL? Happy to test patches, but the below doesn't
>>>> look
>>>> like
>>>> a real fix and more of a work-around.
>>>
> 
> Please try the attached.

I'll give it a test spin right now. Please do add a Reported-by tag,
though. That's always prudent.

-- 
Jens Axboe