diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index ed550d8..3d677dd 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -21,6 +21,11 @@
 	long max_hpages, used_hpages;
 };
 
+extern spinlock_t hugetlb_lock;
+extern int hugetlb_max_hstate __read_mostly;
+#define for_each_hstate(h) \
+	for ((h) = hstates; (h) < &hstates[hugetlb_max_hstate]; (h)++)
+
 struct hugepage_subpool *hugepage_new_subpool(long nr_blocks);
 void hugepage_put_subpool(struct hugepage_subpool *spool);