drm/amdgpu: reserve root PD while releasing it

Otherwise somebody could try to evict it at the same time and try to use
half torn down structures.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-and-Tested-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index c559d76ff695..010d14195a5e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2759,8 +2759,9 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
 {
         struct amdgpu_bo_va_mapping *mapping, *tmp;
         bool prt_fini_needed = !!adev->gart.gart_funcs->set_prt;
+        struct amdgpu_bo *root;
         u64 fault;
-        int i;
+        int i, r;
 
         /* Clear pending page faults from IH when the VM is destroyed */
         while (kfifo_get(&vm->faults, &fault))
@@ -2795,7 +2796,15 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
                 amdgpu_vm_free_mapping(adev, vm, mapping, NULL);
         }
 
-        amdgpu_vm_free_levels(&vm->root);
+        root = amdgpu_bo_ref(vm->root.base.bo);
+        r = amdgpu_bo_reserve(root, true);
+        if (r) {
+                dev_err(adev->dev, "Leaking page tables because BO reservation failed\n");
+        } else {
+                amdgpu_vm_free_levels(&vm->root);
+                amdgpu_bo_unreserve(root);
+        }
+        amdgpu_bo_unref(&root);
         dma_fence_put(vm->last_update);
         for (i = 0; i < AMDGPU_MAX_VMHUBS; i++)
                 amdgpu_vm_free_reserved_vmid(adev, vm, i);