+ if (max_order < MAX_ORDER) {
+ /* If we are here, it means order is >= pageblock_order.
+ * We want to prevent merge between freepages on isolate
+ * pageblock and normal pageblock. Without this, pageblock
+ * isolation could cause incorrect freepage or CMA accounting.
+ *
+ * We don't want to hit this code for the more frequent
+ * low-order merging.
+ */
+ if (unlikely(has_isolate_pageblock(zone))) {
+ int buddy_mt;
+
+ buddy_idx = __find_buddy_index(page_idx, order);
+ buddy = page + (buddy_idx - page_idx);
+ buddy_mt = get_pageblock_migratetype(buddy);
+
+ if (migratetype != buddy_mt
+ && (is_migrate_isolate(migratetype) ||
+ is_migrate_isolate(buddy_mt)))
+ goto done_merging;
+ }
+ max_order++;
+ goto continue_merging;
+ }
+
+done_merging: