[PATCH] drm/amdgpu: Fix last_update fence leak in amdgpu_vm_init()

[Wentao Liang]

amdgpu_vm_init() initializes vm->last_update, vm->last_unlocked and
vm->last_tlb_flush with references to the stub fence taken via
dma_fence_get_stub().  The error label at the end of the function
releases the last_unlocked and last_tlb_flush references with
dma_fence_put(), but the reference stored in vm->last_update is never
dropped, so whenever the page table root creation, the reservation of
the root BO or the PASID registration fails, the stub fence reference
leaks.

Drop the vm->last_update reference together with the other stub fence
references on the error path.

Fixes: 187916e6ed9d ("drm/amdgpu: install stub fence into potential unused fence pointers")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Wentao Liang <vulab@xxxxxxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index fccd758b6699..494197ac20e8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2693,6 +2693,7 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 	amdgpu_bo_unref(&root_bo);
 
 error_free_delayed:
+	dma_fence_put(vm->last_update);
 	dma_fence_put(vm->last_tlb_flush);
 	dma_fence_put(vm->last_unlocked);
 	ttm_lru_bulk_move_fini(&adev->mman.bdev, &vm->lru_bulk_move);
-- 
2.34.1