linux-kernel - Re: Bug: d0e936adbd22 crashes at boot

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Date:   Fri, 3 Sep 2021 14:57:24 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Len Brown <lenb@...nel.org>, linux-pm@...r.kernel.org
Subject: Re: Bug: d0e936adbd22 crashes at boot

On 9/3/21 2:41 PM, Jens Axboe wrote:
> 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@...ux.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.

And you can add Tested-by as well, it works for me.

-- 
Jens Axboe