Re: [PATCH] gpu: Fix uninitialized buddy for built-in drivers

[Matthew Auld <matthew.auld@intel.com>]

On 13/02/2026 17:27, Joel Fernandes wrote:
> On 2/13/2026 10:20 AM, Koen Koning wrote:
>> Move buddy to the start of the link order, so its __init runs before any
>> other built-in drivers that may depend on it. Otherwise, a built-in
>> driver that tries to use the buddy allocator will run into a kernel NULL
>> pointer dereference because slab_blocks is uninitialized.
>>
>> Specifically, this fixes drm/xe (as built-in) running into a kernel
>> panic during boot, because it uses buddy during device probe.
>>
>> Fixes: ba110db8e1bc ("gpu: Move DRM buddy allocator one level up (part two)")
>> Cc: Joel Fernandes <joelagnelf@nvidia.com>
>> Cc: Dave Airlie <airlied@redhat.com>
>> Cc: intel-xe@lists.freedesktop.org
>> Tested-by: Peter Senna Tschudin <peter.senna@linux.intel.com>
>> Signed-off-by: Koen Koning <koen.koning@linux.intel.com>
>> ---
>>   drivers/gpu/Makefile | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
>> index 5cd54d06e262..b4e5e338efa2 100644
>> --- a/drivers/gpu/Makefile
>> +++ b/drivers/gpu/Makefile
>> @@ -2,8 +2,9 @@
>>   # drm/tegra depends on host1x, so if both drivers are built-in care must be
>>   # taken to initialize them in the correct order. Link order is the only way
>>   # to ensure this currently.
>> +# Similarly, buddy must come first since it is used by other drivers.
>> +obj-$(CONFIG_GPU_BUDDY)	+= buddy.o
> 
> Rather than relying on fragile link ordering, would it be better to use an
> earlier initcall level for the buddy allocator?

Ok, makes sense. Should we go with something like 
subsys_initcall(gpu_buddy_module_init) here?

> 
> Thanks,
>