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

[Joel Fernandes <joelagnelf@nvidia.com>]

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?

Thanks,

-- 
Joel Fernandes