VM_MAP_DYING
if ((map->flags & VM_MAP_DYING) == 0) {
map->flags |= VM_MAP_DYING;
map->flags &= ~VM_MAP_DYING;
KASSERT((vm->vm_map.flags & VM_MAP_DYING) == 0);
map->flags |= VM_MAP_DYING;
#ifdef VM_MAP_DYING
D(vm_map, vm_map)->flags & VM_MAP_DYING ? " DYING" :