radix_tree_empty
WARN_ON(!radix_tree_empty(&nullb->dev->cache));
if (GEM_WARN_ON(!radix_tree_empty(&vgpu->gtt.spt_tree))) {
WARN(!radix_tree_empty(&alink->qdiscs), "left over qdiscs\n");
return radix_tree_empty(&idr->idr_rt) &&
WARN_ON(!radix_tree_empty(&domain->revmap_tree));
BUG_ON(!radix_tree_empty(&mt_tree));