diff --git a/mm/internal.h b/mm/internal.h
index da6b9b2..3314f79 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -353,3 +353,5 @@
 extern unsigned long vm_mmap_pgoff(struct file *, unsigned long,
         unsigned long, unsigned long,
         unsigned long, unsigned long);
+
+extern void set_pageblock_order(void);