PK_MARKER
KASSERT((p->p_flag & PK_MARKER) == 0);
marker.p_flag = PK_MARKER;
if (p->p_flag & PK_MARKER) {
marker->p_flag = PK_MARKER;
if ((p->p_flag & PK_MARKER) != 0)
while (p != NULL && p->p_flag & PK_MARKER)