diff --git a/src/emqx_channel.erl b/src/emqx_channel.erl
index da412126e..1b20753aa 100644
--- a/src/emqx_channel.erl
+++ b/src/emqx_channel.erl
@@ -945,7 +945,7 @@ handle_info({sock_closed, Reason}, Channel =
         Shutdown -> Shutdown
     end;
 
-handle_info({sock_closed, Reason}, Channel = #channel{conn_state = disconnected}) ->
+handle_info({sock_closed, _Reason}, Channel = #channel{conn_state = disconnected}) ->
     %% Since sock_closed messages can be generated multiple times,
     %% we can simply ignore errors of this type in the disconnected state.
     %% e.g. when the socket send function returns an error, there is already
diff --git a/src/emqx_cm.erl b/src/emqx_cm.erl
index 10a5dbfff..2e917ca79 100644
--- a/src/emqx_cm.erl
+++ b/src/emqx_cm.erl
@@ -72,6 +72,9 @@
 %% Internal export
 -export([stats_fun/0, clean_down/1]).
 
+%% Test export
+-export([register_channel_/3]).
+
 -type(chan_pid() :: pid()).
 
 %% Tables for channel management.
@@ -88,14 +91,12 @@
 %% Batch drain
 -define(BATCH_SIZE, 100000).
 
--define(T_TAKEOVER, 15000).
-
 %% Server name
 -define(CM, ?MODULE).
 
--define(T_KICK, 5_000).
--define(T_GET_INFO, 5_000).
--define(T_TAKEOVER, 15_000).
+-define(T_KICK, 5000).
+-define(T_GET_INFO, 5000).
+-define(T_TAKEOVER, 15000).
 
 %% @doc Start the channel manager.
 -spec(start_link() -> startlink_ret()).
@@ -298,28 +299,26 @@ kick_or_kill(Action, ConnMod, Pid) ->
         ok = apply(ConnMod, call, [Pid, Action, ?T_KICK])
     catch
         _ : noproc -> % emqx_ws_connection: call
-            ok = ?tp(debug, "session_already_gone", #{pid => Pid, action => Action});
+            ?LOG(debug, "session_already_gone: ~p, action: ~p", [Pid, Action]),
+            ok;
         _ : {noproc, _} -> % emqx_connection: gen_server:call
-            ok = ?tp(debug, "session_already_gone", #{pid => Pid, action => Action});
+            ?LOG(debug, "session_already_gone: ~p, action: ~p", [Pid, Action]),
+            ok;
         _ : {shutdown, _} ->
-            ok = ?tp(debug, "session_already_shutdown", #{pid => Pid, action => Action});
+            ?LOG(debug, "session_already_shutdown: ~p, action: ~p", [Pid, Action]),
+            ok;
         _ : {{shutdown, _}, _} ->
-            ok = ?tp(debug, "session_already_shutdown", #{pid => Pid, action => Action});
+            ?LOG(debug, "session_already_shutdown: ~p, action: ~p", [Pid, Action]),
+            ok;
         _ : {timeout, {gen_server, call, _}} ->
-            ?tp(warning, "session_kick_timeout",
-                #{pid => Pid,
-                  action => Action,
-                  stale_channel => stale_channel_info(Pid)
-                 }),
+            ?LOG(warning, "session_kick_timeout: ~p, action: ~p, "
+                          "stale_channel: ~p",
+                          [Pid, Action, stale_channel_info(Pid)]),
             ok = force_kill(Pid);
-        _ : Error : St ->
-            ?tp(error, "session_kick_exception",
-                #{pid => Pid,
-                  action => Action,
-                  reason => Error,
-                  stacktrace => St,
-                  stale_channel => stale_channel_info(Pid)
-                 }),
+        _ : Error ->
+            ?LOG(error, "session_kick_exception: ~p, action: ~p, "
+                        "reason: ~p, stacktrace: ~p, stale_channel: ~p",
+                        [Pid, Action, Error, erlang:get_stacktrace(), stale_channel_info(Pid)]),
             ok = force_kill(Pid)
     end.
 
diff --git a/test/emqx_cm_SUITE.erl b/test/emqx_cm_SUITE.erl
index 62c745828..ec660429a 100644
--- a/test/emqx_cm_SUITE.erl
+++ b/test/emqx_cm_SUITE.erl
@@ -211,9 +211,9 @@ test_kick_session(Action, Reason) ->
         end,
     {Pid1, _} = spawn_monitor(FakeSessionFun),
     {Pid2, _} = spawn_monitor(FakeSessionFun),
-    ok = emqx_cm:register_channel(ClientId, Pid1, ConnInfo),
-    ok = emqx_cm:register_channel(ClientId, Pid1, ConnInfo),
-    ok = emqx_cm:register_channel(ClientId, Pid2, ConnInfo),
+    ok = emqx_cm:register_channel_(ClientId, Pid1, ConnInfo),
+    ok = emqx_cm:register_channel_(ClientId, Pid1, ConnInfo),
+    ok = emqx_cm:register_channel_(ClientId, Pid2, ConnInfo),
     ?assertEqual([Pid1, Pid2], lists:sort(emqx_cm:lookup_channels(ClientId))),
     case Reason of
         noproc -> exit(Pid1, kill), exit(Pid2, kill);
@@ -225,15 +225,18 @@ test_kick_session(Action, Reason) ->
          end,
     case Reason =:= timeout orelse Reason =:= noproc of
         true ->
-            ?assertEqual(killed, ?WAIT({'DOWN', _, process, Pid1, R}, 2_000, R)),
-            ?assertEqual(killed, ?WAIT({'DOWN', _, process, Pid2, R}, 2_000, R));
+            ?assertEqual(killed, ?WAIT({'DOWN', _, process, Pid1, R}, 2000, R)),
+            ?assertEqual(killed, ?WAIT({'DOWN', _, process, Pid2, R}, 2000, R));
         false ->
-            ?assertEqual(Reason, ?WAIT({'DOWN', _, process, Pid1, R}, 2_000, R)),
-            ?assertEqual(Reason, ?WAIT({'DOWN', _, process, Pid2, R}, 2_000, R))
+            ?assertEqual(Reason, ?WAIT({'DOWN', _, process, Pid1, R}, 2000, R)),
+            ?assertEqual(Reason, ?WAIT({'DOWN', _, process, Pid2, R}, 2000, R))
     end,
     ok = flush_emqx_pool(),
     ?assertEqual([], emqx_cm:lookup_channels(ClientId)).
 
+rand_client_id() ->
+    list_to_binary("client-id-" ++ integer_to_list(erlang:system_time())).
+
 %% Channel deregistration is delegated to emqx_pool as a sync tasks.
 %% The emqx_pool is pool of workers, and there is no way to know
 %% which worker was picked for the last deregistration task.