1 files changed, 13 insertions, 3 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a2955e101715..da526905b4a5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -509,16 +509,26 @@ static inline int page_is_buddy(struct page *page, struct page *buddy,
         if (!pfn_valid_within(page_to_pfn(buddy)))
                 return 0;
 
-        if (page_zone_id(page) != page_zone_id(buddy))
-                return 0;
-
         if (page_is_guard(buddy) && page_order(buddy) == order) {
                 VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+
+                if (page_zone_id(page) != page_zone_id(buddy))
+                        return 0;
+
                 return 1;
         }
 
         if (PageBuddy(buddy) && page_order(buddy) == order) {
                 VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+
+                /*
+                 * zone check is done late to avoid uselessly
+                 * calculating zone/node ids for pages that could
+                 * never merge.
+                 */
+                if (page_zone_id(page) != page_zone_id(buddy))
+                        return 0;
+
                 return 1;
         }
         return 0;