1 files changed, 15 insertions, 0 deletions

diff --git a/mm/mmzone.c b/mm/mmzone.c
index 16ce8b955dc..f5b7d176021 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -6,6 +6,7 @@
 
 
 #include <linux/stddef.h>
+#include <linux/mm.h>
 #include <linux/mmzone.h>
 #include <linux/module.h>
 
@@ -72,3 +73,17 @@ struct zoneref *next_zones_zonelist(struct zoneref *z,
         *zone = zonelist_zone(z);
         return z;
 }
+
+#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
+int memmap_valid_within(unsigned long pfn,
+                                        struct page *page, struct zone *zone)
+{
+        if (page_to_pfn(page) != pfn)
+                return 0;
+
+        if (page_zone(page) != zone)
+                return 0;
+
+        return 1;
+}
+#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */