diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
index dca7d823ad57..04096fb8b8d9 100644
--- a/tools/memory-model/litmus-tests/README
+++ b/tools/memory-model/litmus-tests/README
@@ -32,6 +32,12 @@ IRIW+poonceonces+OnceOnce.litmus
 	order of a pair of writes, where each write is to a different
 	variable by a different process?
 
+ISA2+pooncelock+pooncelock+pombonce.litmus
+	Tests whether the ordering provided by a lock-protected S
+	litmus test is visible to an external process whose accesses are
+	separated by smp_mb().	This addition of an external process to
+	S is otherwise known as ISA2.
+
 ISA2+poonceonces.litmus
 	As below, but with store-release replaced with WRITE_ONCE()
 	and load-acquire replaced with READ_ONCE().