drm_vma_node_allow
ret = drm_vma_node_allow(&obj->vma_node, vma->vm_file->private_data);
ret = drm_vma_node_allow(&obj->vma_node, file_priv);
EXPORT_SYMBOL(drm_vma_node_allow);
int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag);