diff --git a/Documentation/userspace-api/netlink/intro.rst b/Documentation/userspace-api/netlink/intro.rst
index 7b1d401210ef..aacffade8f84 100644
--- a/Documentation/userspace-api/netlink/intro.rst
+++ b/Documentation/userspace-api/netlink/intro.rst
@@ -234,6 +234,10 @@ ACK attributes may be present::
   | ** optionally extended ACK                 |
   ----------------------------------------------
 
+Note that some implementations may issue custom ``NLMSG_DONE`` messages
+in reply to ``do`` action requests. In that case the payload is
+implementation-specific and may also be absent.
+
 .. _res_fam:
 
 Resolving the Family ID