diff --git a/mm/slab.c b/mm/slab.c
index a041c53..05a3910 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2998,6 +2998,8 @@
  * kfree - free previously allocated memory
  * @objp: pointer returned by kmalloc.
  *
+ * If @objp is NULL, no operation is performed.
+ *
  * Don't free memory not originally allocated by kmalloc()
  * or you will run into trouble.
  */