PS_RUMP_LWPEXIT
p->p_sflag |= PS_RUMP_LWPEXIT;
KASSERT(p->p_nlwps == 1 && p->p_sflag & PS_RUMP_LWPEXIT);
p->p_sflag &= ~PS_RUMP_LWPEXIT;
while ((p->p_sflag & PS_RUMP_LWPEXIT) == 0) {
KASSERT(p->p_sflag & PS_RUMP_LWPEXIT);
KASSERT((p->p_sflag & PS_RUMP_LWPEXIT) == 0);
if (p->p_sflag & PS_RUMP_LWPEXIT) {