1 files changed, 6 insertions, 9 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index dde04ff..eec89ab 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -169,20 +169,17 @@ static void bad_page(struct page *page)
  * All pages have PG_compound set.  All pages have their ->private pointing at
  * the head page (even the head page has this).
  *
- * The first tail page's ->mapping, if non-zero, holds the address of the
- * compound page's put_page() function.
- *
- * The order of the allocation is stored in the first tail page's ->index
- * This is only for debug at present.  This usage means that zero-order pages
- * may not be compound.
+ * The first tail page's ->lru.next holds the address of the compound page's
+ * put_page() function.  Its ->lru.prev holds the order of allocation.
+ * This usage means that zero-order pages may not be compound.
  */
 static void prep_compound_page(struct page *page, unsigned long order)
 {
 	int i;
 	int nr_pages = 1 << order;
 
-	page[1].mapping = NULL;
-	page[1].index = order;
+	page[1].lru.next = NULL;			/* set dtor */
+	page[1].lru.prev = (void *)order;
 	for (i = 0; i < nr_pages; i++) {
 		struct page *p = page + i;
 
@@ -196,7 +193,7 @@ static void destroy_compound_page(struct page *page, unsigned long order)
 	int i;
 	int nr_pages = 1 << order;
 
-	if (unlikely(page[1].index != order))
+	if (unlikely((unsigned long)page[1].lru.prev != order))
 		bad_page(page);
 
 	for (i = 0; i < nr_pages; i++) {