diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst
index 286d16fc22ebb..02b8206a35941 100644
--- a/Documentation/admin-guide/cgroup-v1/memory.rst
+++ b/Documentation/admin-guide/cgroup-v1/memory.rst
@@ -90,6 +90,7 @@ Brief summary of control files.
                                      used.
  memory.swappiness		     set/show swappiness parameter of vmscan
 				     (See sysctl's vm.swappiness)
+				     Per memcg knob does not exist in cgroup v2.
  memory.move_charge_at_immigrate     This knob is deprecated.
  memory.oom_control		     set/show oom controls.
                                      This knob is deprecated and shouldn't be
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index a071fa43d4798..93291c0e6eac5 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -1855,9 +1855,11 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
 	if (val > MAX_SWAPPINESS)
 		return -EINVAL;
 
-	if (!mem_cgroup_is_root(memcg))
+	if (!mem_cgroup_is_root(memcg)) {
+		pr_info_once("Per memcg swappiness does not exist in cgroup v2. "
+			     "See memory.reclaim or memory.swap.max there\n ")
 		WRITE_ONCE(memcg->swappiness, val);
-	else
+	} else
 		WRITE_ONCE(vm_swappiness, val);
 
 	return 0;