1 files changed, 17 insertions, 12 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d677706..3686006 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -407,20 +407,25 @@ static inline void compound_unlock_irqrestore(struct page *page,
 #endif
 }
 
+static inline struct page *compound_head_by_tail(struct page *tail)
+{
+	struct page *head = tail->first_page;
+
+	/*
+	 * page->first_page may be a dangling pointer to an old
+	 * compound page, so recheck that it is still a tail
+	 * page before returning.
+	 */
+	smp_rmb();
+	if (likely(PageTail(tail)))
+		return head;
+	return tail;
+}
+
 static inline struct page *compound_head(struct page *page)
 {
-	if (unlikely(PageTail(page))) {
-		struct page *head = page->first_page;
-
-		/*
-		 * page->first_page may be a dangling pointer to an old
-		 * compound page, so recheck that it is still a tail
-		 * page before returning.
-		 */
-		smp_rmb();
-		if (likely(PageTail(page)))
-			return head;
-	}
+	if (unlikely(PageTail(page)))
+		return compound_head_by_tail(page);
 	return page;
 }