drm/amdgpu: Handle NULL bo->tbo.resource (again) in amdgpu_vm_bo_update

commit 85230ee36d88e7a09fb062d43203035659dd10a5 upstream.

Third time's the charm, I hope?

Fixes: d311675 ("drm/ttm: rename bo->mem and make it a pointer")
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3837
Reviewed-by: Christian König <[email protected]>
Signed-off-by: Michel Dänzer <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
(cherry picked from commit 695c2c745e5dff201b75da8a1d237ce403600d04)
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Michel Dänzer

drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c

@@ -1060,10 +1060,9 @@ int amdgpu_vm_bo_update(struct amdgpu_device *adev, struct amdgpu_bo_va *bo_va,
 	 * next command submission.
 	 */
 	if (bo && bo->tbo.base.resv == vm->root.bo->tbo.base.resv) {
-		uint32_t mem_type = bo->tbo.resource->mem_type;
-
-		if (!(bo->preferred_domains &
-		      amdgpu_mem_type_to_domain(mem_type)))
+		if (bo->tbo.resource &&
+		    !(bo->preferred_domains &
+		      amdgpu_mem_type_to_domain(bo->tbo.resource->mem_type)))
 			amdgpu_vm_bo_evicted(&bo_va->base);
 		else
 			amdgpu_vm_bo_idle(&bo_va->base);