V_sack_hole_zone
hole = (struct sackhole *)uma_zalloc(V_sack_hole_zone, M_NOWAIT);
uma_zfree(V_sack_hole_zone, hole);
V_sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
uma_zdestroy(V_sack_hole_zone);