FUTEX_READ
if (err == -EFAULT && rw == FUTEX_READ) {
ret = get_futex_key(uaddr1, flags1, &key1, FUTEX_READ);
requeue_pi ? FUTEX_WRITE : FUTEX_READ);
ret = get_futex_key(uaddr, flags, &key, FUTEX_READ);
ret = get_futex_key(uaddr1, flags, &key1, FUTEX_READ);
&vs[i].q.key, FUTEX_READ);
ret = get_futex_key(uaddr, flags, &q->key, FUTEX_READ);