diff --git a/mm/memory.c b/mm/memory.c
index 5956d6f..ab749d7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1977,7 +1977,7 @@
 	unsigned long end = addr + size;
 	int err;
 
-	if (WARN_ON(addr >= end))
+	if (WARN_ON(addr >= end - 1))
 		return -EINVAL;
 
 	pgd = pgd_offset(mm, addr);