Merge branch 'core/xen' into x86/xen

1 files changed, 18 insertions, 1 deletions

diff --git a/mm/vmstat.c b/mm/vmstat.c
index b0d08e667ece..d7826af2fb07 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -516,9 +516,26 @@ 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)
+                        continue;
+#endif
                 mtype = get_pageblock_migratetype(page);
 
-                count[mtype]++;
+                if (mtype < MIGRATE_TYPES)
+                        count[mtype]++;
         }
 
         /* Print counts */