extern unsigned long highest_memmap_pfn;
+#ifdef CONFIG_SMP
+extern int putback_active_lru_page(struct zone *zone, struct page *page);
+#else
+static inline int putback_active_lru_page(struct zone *zone, struct page *page)
+{
+ return 0;
+}
+#endif
+
/*
* in mm/vmscan.c:
*/