diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 715b651e35a0..7f355316704c 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -481,6 +481,8 @@ void kernfs_put_active(struct kernfs_node *kn)
 /**
  * kernfs_drain - drain kernfs_node
  * @kn: kernfs_node to drain
+ * @drop_supers: Set to true if this function is called with the
+ *               kernfs_supers_rwsem locked.
  *
  * Drain existing usages and nuke all existing mmaps of @kn.  Multiple
  * removers may invoke this function concurrently on @kn and all will