3 files changed, 20 insertions, 16 deletions

diff --git a/mm/mmzone.c b/mm/mmzone.c
index 16ce8b955dcf..f5b7d1760213 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 */
diff --git a/mm/rmap.c b/mm/rmap.c
index 16521664010d..23122af32611 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -14,7 +14,7 @@
  * Original design by Rik van Riel <riel@conectiva.com.br> 2001
  * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
  * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
- * Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004
+ * Contributions by Hugh Dickins 2003, 2004
  */
 
 /*
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 66f6130976cb..74d66dba0cbe 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -509,22 +509,11 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m,
                         continue;
 
                 page = pfn_to_page(pfn);
-#ifdef CONFIG_ARCH_FLATMEM_HAS_HOLES
-                /*
-                 * Ordinarily, memory holes in flatmem still have a valid
-                 * memmap for the PFN range. However, an architecture for
-                 * embedded systems (e.g. ARM) can free up the memmap backing
-                 * holes to save memory on the assumption the memmap is
-                 * never used. The page_zone linkages are then broken even
-                 * though pfn_valid() returns true. Skip the page if the
-                 * linkages are broken. Even if this test passed, the impact
-                 * is that the counters for the movable type are off but
-                 * fragmentation monitoring is likely meaningless on small
-                 * systems.
-                 */
-                if (page_zone(page) != zone)
+
+                /* Watch for unexpected holes punched in the memmap */
+                if (!memmap_valid_within(pfn, page, zone))
                         continue;
-#endif
+
                 mtype = get_pageblock_migratetype(page);
 
                 if (mtype < MIGRATE_TYPES)