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

[Koen Koning <koen.koning@linux.intel.com>]

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-$(CONFIG_GPU_BUDDY)	+= buddy.o
 obj-y			+= host1x/ drm/ vga/ tests/
 obj-$(CONFIG_IMX_IPUV3_CORE)	+= ipu-v3/
 obj-$(CONFIG_TRACE_GPU_MEM)		+= trace/
 obj-$(CONFIG_NOVA_CORE)		+= nova-core/
-obj-$(CONFIG_GPU_BUDDY)		+= buddy.o
-- 
2.48.1