diff --git a/man7/cgroups.7 b/man7/cgroups.7
index 2045ce387..6950cefd3 100644
--- a/man7/cgroups.7
+++ b/man7/cgroups.7
@@ -1147,6 +1147,8 @@ With the addition of threads mode,
 cgroups v2 now distinguishes two types of resource controllers:
 .IP * 3
 .I Threaded
+.\" In the kernel source, look for ".threaded[ \t]*= true" in 
+.\" initializations of struct cgroup_subsys
 controllers: these controllers support thread-granularity for
 resource control and can be enabled inside threaded subtrees,
 with the result that the corresponding controller-interface files