diff --git a/mm/truncate.c b/mm/truncate.c
index ff78505..cadc156 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -8,6 +8,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/backing-dev.h>
 #include <linux/mm.h>
 #include <linux/swap.h>
 #include <linux/module.h>