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-rw-r--r--mm/page_alloc.c16
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;