[PATCH 2/2] drm/amdgpu: Avoid endless loop in GPUVM fragment processing

[Christian König]

Am 26.11.18 um 23:01 schrieb Kuehling, Felix:
> Don't bounce back to the root level for fragment processing, because
> huge pages are not supported at that level. This is unlikely to happen
> with the default VM size on Vega, but can be exposed by limiting the
> VM size with the amdgpu.vm_size module parameter.
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>

Good catch! Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index be3e360..0877ff9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -1656,9 +1656,11 @@ static int amdgpu_vm_update_ptes(struct amdgpu_pte_update_params *params,
>   			if (!amdgpu_vm_pt_descendant(adev, &cursor))
>   				return -ENOENT;
>   			continue;
> -		} else if (frag >= parent_shift) {
> +		} else if (frag >= parent_shift &&
> +			   cursor.level - 1 != adev->vm_manager.root_level) {
>   			/* If the fragment size is even larger than the parent
> -			 * shift we should go up one level and check it again.
> +			 * shift we should go up one level and check it again
> +			 * unless one level up is the root level.
>   			 */
>   			if (!amdgpu_vm_pt_ancestor(&cursor))
>   				return -ENOENT;