Linux 6.12.4 - crash dma_alloc_attrs+0x12b via ipu6

[Jani Nikula]

On Tue, 10 Dec 2024, Genes Lists <lists at sapience.com> wrote:
> On Tue, 2024-12-10 at 10:58 +0200, Jani Nikula wrote:
>> On Tue, 10 Dec 2024, Sakari Ailus <sakari.ailus at linux.intel.com>
>> wrote:
>> > Hi,
>> > 
>> > > ...
>> > > FYI 6.12.4 got a crash shortly after booting in dma_alloc_attrs -
>> > > maybe
>> > > triggered in ipu6_probe. Crash only happened on laptop with ipu6.
>> > > All
>> > > other machines are running fine.
>> > 
>> > Have you read the dmesg further than the IPU6 related warning? The
>> > IPU6
>> > driver won't work (maybe not even probe?) but if the system
>> > crashes, it
>> > appears unlikely the IPU6 drivers would have something to do with
>> > that.
>> > Look for warnings on linked list corruption later, they seem to be
>> > coming
>> > from the i915 driver.
>> 
>> And the list corruption is actually happening in
>> cpu_latency_qos_update_request(). I don't see any i915 changes in
>> 6.12.4
>> that could cause it.
>> 
>> I guess the question is, when did it work? Did 6.12.3 work?
>> 
>> 
>> BR,
>> Jani.
>
>
>  - 6.12.1 worked
>
>  - mainline - works (but only with i915 patch set [1] otherwise there
> are no graphics at all)
>
>     [1] https://patchwork.freedesktop.org/series/141911/
>
> - 6.12.3 - crashed (i see i915 not ipu6) and again it has       
>     cpu_latency_qos_update_request+0x61/0xc0

Thanks for testing.

There are no changes to either i915 or kernel/power between 6.12.1 and
6.12.4.

There are some changes to drm core, but none that could explain this.

Maybe try the same kernels a few more times to see if it's really
deterministic? Not that I have obvious ideas where to go from there, but
it's a clue nonetheless.

BR,
Jani.


-- 
Jani Nikula, Intel