1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e266fe1b4c4..a17b147c61e7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -296,6 +296,24 @@ void put_pages_list(struct list_head *pages);
 void split_page(struct page *page, unsigned int order);
 
 /*
+ * Compound pages have a destructor function.  Provide a
+ * prototype for that function and accessor functions.
+ * These are _only_ valid on the head of a PG_compound page.
+ */
+typedef void compound_page_dtor(struct page *);
+
+static inline void set_compound_page_dtor(struct page *page,
+						compound_page_dtor *dtor)
+{
+	page[1].lru.next = (void *)dtor;
+}
+
+static inline compound_page_dtor *get_compound_page_dtor(struct page *page)
+{
+	return (compound_page_dtor *)page[1].lru.next;
+}
+
+/*
  * Multiple processes may "see" the same page. E.g. for untouched
  * mappings of /dev/null, all processes see the same page full of
  * zeroes, and text pages of executables and shared libraries have