CARP_VHAF_ONLIST
KKASSERT((vha_new->vha_flags & CARP_VHAF_ONLIST) == 0);
vha_new->vha_flags |= CARP_VHAF_ONLIST;
KKASSERT(vha->vha_flags & CARP_VHAF_ONLIST);
vha->vha_flags &= ~CARP_VHAF_ONLIST;