[PATCH] drm/amdgpu: reserve root PD while releasing it

[Deucher, Alexander]

> -----Original Message-----
> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
> Of Christian König
> Sent: Friday, October 13, 2017 11:26 AM
> To: amd-gfx at lists.freedesktop.org
> Subject: [PATCH] drm/amdgpu: reserve root PD while releasing it
> 
> From: Christian König <christian.koenig at amd.com>
> 
> Otherwise somebody could try to evict it at the same time and try to use
> halve torn down structures.
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 13 +++++++++++--
>  1 file 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 b72ef2c652d0..ef8b7a9a735a 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))
> @@ -2794,7 +2795,15 @@ 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);
> --
> 2.11.0
> 
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