From: Ben Skeggs <bskeggs@redhat.com>
Date: Tue, 28 Aug 2018 14:10:42 +1000
Subject: drm/nouveau/mmu: don't attempt to dereference vmm without valid
 instance pointer
Git-commit: 51ed833c881b9d96557c773f6a37018d79e29a46
Patch-mainline: v4.19-rc4
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Fixes oopses in certain failure paths.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -1423,7 +1423,7 @@ nvkm_vmm_get(struct nvkm_vmm *vmm, u8 pa
 void
 nvkm_vmm_part(struct nvkm_vmm *vmm, struct nvkm_memory *inst)
 {
-	if (vmm->func->part && inst) {
+	if (inst && vmm->func->part) {
 		mutex_lock(&vmm->mutex);
 		vmm->func->part(vmm, inst);
 		mutex_unlock(&vmm->mutex);