LW_USERRET
if (__predict_false(curlwp->l_flag & LW_USERRET)) {
if ((f = atomic_load_relaxed(&l->l_flag) & LW_USERRET) == 0) {
if ((l2->l_flag & LW_USERRET) != 0) {
exception = l->l_cpu->ci_want_resched | (l->l_flag & LW_USERRET);