diff --git a/mm/internal.h b/mm/internal.h
index 814da33..04bbce8 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -251,5 +251,7 @@
 #define ZONE_RECLAIM_SUCCESS	1
 #endif
 
+extern int hwpoison_filter(struct page *p);
+
 extern u32 hwpoison_filter_dev_major;
 extern u32 hwpoison_filter_dev_minor;