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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>, inux-pm@vger.kernel.org
References: <942f4041-e4e7-1b08-3301-008ab37ff5b8@kernel.dk>
 <c56cde110210bec6537fe69b495334c6c70c814e.camel@linux.intel.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <3ac87893-55ba-f2d4-bb1e-382868f12d4c@kernel.dk>
Date:   Fri, 3 Sep 2021 08:15:29 -0600
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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.

-- 
Jens Axboe