diff --git a/mm/internal.h b/mm/internal.h
index 2189af4..aee4761 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -100,6 +100,39 @@
 extern bool is_free_buddy_page(struct page *page);
 #endif
 
+#if defined CONFIG_COMPACTION || defined CONFIG_CMA
+
+/*
+ * in mm/compaction.c
+ */
+/*
+ * compact_control is used to track pages being migrated and the free pages
+ * they are being migrated to during memory compaction. The free_pfn starts
+ * at the end of a zone and migrate_pfn begins at the start. Movable pages
+ * are moved to the end of a zone during a compaction run and the run
+ * completes when free_pfn <= migrate_pfn
+ */
+struct compact_control {
+	struct list_head freepages;	/* List of free pages to migrate to */
+	struct list_head migratepages;	/* List of pages being migrated */
+	unsigned long nr_freepages;	/* Number of isolated free pages */
+	unsigned long nr_migratepages;	/* Number of pages to migrate */
+	unsigned long free_pfn;		/* isolate_freepages search base */
+	unsigned long migrate_pfn;	/* isolate_migratepages search base */
+	bool sync;			/* Synchronous migration */
+
+	int order;			/* order a direct compactor needs */
+	int migratetype;		/* MOVABLE, RECLAIMABLE etc */
+	struct zone *zone;
+};
+
+unsigned long
+isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn);
+unsigned long
+isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
+			   unsigned long low_pfn, unsigned long end_pfn);
+
+#endif
 
 /*
  * function for dealing with page's order in buddy system.