uvm_map_fix_space
uvm_map_fix_space(map, first, VMMAP_FREE_START(first),
uvm_map_fix_space(map, entry, min, max, flags);
struct vm_map_entry *uvm_map_fix_space(struct vm_map*, struct vm_map_entry*,
*prev_ptr = uvm_map_fix_space(map, prev, addr, end, 0);
uvm_map_fix_space(map, NULL, map->min_offset, map->max_offset, 0);
entry = uvm_map_fix_space(map, entry, min, max, flags);