diff --git a/mm/slab.c b/mm/slab.c
index a041c5378dfa59895c411d07b88cf69153275a11..05a391059fe1d92b58a85fb5cb1e3039f6fa6468 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2998,6 +2998,8 @@ EXPORT_SYMBOL(kzalloc);
  * 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.
  */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 67b358e57ef67af05279196408c6c0bc430180c3..13c3d82968ae2a1e363dcc16e47474a716c5952d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -332,9 +332,10 @@ void __vunmap(void *addr, int deallocate_pages)
  *	@addr:		memory base address
  *
  *	Free the virtually contiguous memory area starting at @addr, as
- *	obtained from vmalloc(), vmalloc_32() or __vmalloc().
+ *	obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
+ *	NULL, no operation is performed.
  *
- *	May not be called in interrupt context.
+ *	Must not be called in interrupt context.
  */
 void vfree(void *addr)
 {
@@ -352,7 +353,7 @@ EXPORT_SYMBOL(vfree);
  *	Free the virtually contiguous memory area starting at @addr,
  *	which was created from the page array passed to vmap().
  *
- *	May not be called in interrupt context.
+ *	Must not be called in interrupt context.
  */
 void vunmap(void *addr)
 {