compact_gap
watermark += compact_gap(order);
if (!__zone_watermark_ok(zone, 0, watermark + compact_gap(order),
if (sc->nr_reclaimed >= max(sc->nr_to_reclaim, compact_gap(sc->order)))
pages_for_compaction = compact_gap(sc->order);
if (sc->order && sc->nr_reclaimed >= compact_gap(sc->order))