How can you efficiently check the VM mapping for an address?

bool is_address_valid(ADDRINT addr) {
  static int pagesize = getpagesize();

  const void *foo = (const void *)(addr / pagesize * pagesize);

  if (munlock(foo, 1) == -1) {
    fprintf(stderr, "munlock(%p=>%p, 1) failed: %sn", addr, foo,
            strerror(errno));
    return false;
  }
  return true;
}