addr_to_node
vn = addr_to_node(va_start_lowest);
struct vmap_node *vn = addr_to_node(va->va_start);
vn = addr_to_node(va->va_start);
id_to_node(vn_id):addr_to_node(va->va_start);
vn = addr_to_node(vb->va->va_start);
struct vmap_node *vn = addr_to_node(vas[area]->va_start);
vn = addr_to_node(addr);
vn = addr_to_node(va->va_start);