diff --git a/apps/emqx/src/emqx_channel.erl b/apps/emqx/src/emqx_channel.erl
index 536c9bd37..93cd872c4 100644
--- a/apps/emqx/src/emqx_channel.erl
+++ b/apps/emqx/src/emqx_channel.erl
@@ -939,8 +939,8 @@ handle_deliver(
         clientinfo = ClientInfo
     }
 ) ->
-    % NOTE
-    % This is essentially part of `emqx_session_mem` logic, thus call it directly.
+    %% NOTE
+    %% This is essentially part of `emqx_session_mem` logic, thus call it directly.
     Delivers1 = maybe_nack(Delivers),
     Messages = emqx_session:enrich_delivers(ClientInfo, Delivers1, Session),
     NSession = emqx_session_mem:enqueue(ClientInfo, Messages, Session),
@@ -1072,10 +1072,10 @@ return_connack(AckPacket, Channel) ->
             },
             {Packets, NChannel2} = do_deliver(Publishes, NChannel1),
             Outgoing = [?REPLY_OUTGOING(Packets) || length(Packets) > 0],
-            % NOTE
-            % Session timers are not restored here, so there's a tiny chance that
-            % the session becomes stuck, when it already has no place to track new
-            % messages.
+            %% NOTE
+            %% Session timers are not restored here, so there's a tiny chance that
+            %% the session becomes stuck, when it already has no place to track new
+            %% messages.
             {ok, Replies ++ Outgoing, NChannel2}
     end.
 
@@ -1172,8 +1172,8 @@ handle_call(
         conninfo = #{clientid := ClientId}
     }
 ) ->
-    % NOTE
-    % This is essentially part of `emqx_session_mem` logic, thus call it directly.
+    %% NOTE
+    %% This is essentially part of `emqx_session_mem` logic, thus call it directly.
     ok = emqx_session_mem:takeover(Session),
     %% TODO: Should not drain deliver here (side effect)
     Delivers = emqx_utils:drain_deliver(),
diff --git a/apps/emqx/src/emqx_persistent_session_ds.erl b/apps/emqx/src/emqx_persistent_session_ds.erl
index 6060aa4a4..f37eb7710 100644
--- a/apps/emqx/src/emqx_persistent_session_ds.erl
+++ b/apps/emqx/src/emqx_persistent_session_ds.erl
@@ -104,12 +104,12 @@ create(#{clientid := ClientID}, _ConnInfo, Conf) ->
 -spec open(clientinfo(), conninfo(), emqx_session:conf()) ->
     {_IsPresent :: true, session(), []} | {_IsPresent :: false, session()}.
 open(#{clientid := ClientID}, _ConnInfo, Conf) ->
-    % NOTE
-    % The fact that we need to concern about discarding all live channels here
-    % is essentially a consequence of the in-memory session design, where we
-    % have disconnected channels holding onto session state. Ideally, we should
-    % somehow isolate those idling not-yet-expired sessions into a separate process
-    % space, and move this call back into `emqx_cm` where it belongs.
+    %% NOTE
+    %% The fact that we need to concern about discarding all live channels here
+    %% is essentially a consequence of the in-memory session design, where we
+    %% have disconnected channels holding onto session state. Ideally, we should
+    %% somehow isolate those idling not-yet-expired sessions into a separate process
+    %% space, and move this call back into `emqx_cm` where it belongs.
     ok = emqx_cm:discard_session(ClientID),
     {IsNew, Session} = open_session(ClientID, Conf),
     IsPresent = not IsNew,
diff --git a/apps/emqx/src/emqx_session_mem.erl b/apps/emqx/src/emqx_session_mem.erl
index 586196d36..578a4fb68 100644
--- a/apps/emqx/src/emqx_session_mem.erl
+++ b/apps/emqx/src/emqx_session_mem.erl
@@ -185,8 +185,8 @@ get_mqtt_conf(Zone, Key, Default) ->
 
 -spec destroy(session() | clientinfo()) -> ok.
 destroy(_Session) ->
-    % NOTE
-    % This is a stub. This session impl has no backing store, thus always `ok`.
+    %% NOTE
+    %% This is a stub. This session impl has no backing store, thus always `ok`.
     ok.
 
 %%--------------------------------------------------------------------
@@ -674,20 +674,20 @@ resume(ClientInfo = #{clientid := ClientId}, Session = #session{subscriptions =
 -spec replay(emqx_types:clientinfo(), replayctx(), session()) ->
     {ok, replies(), session()}.
 replay(ClientInfo, Pendings, Session) ->
-    % NOTE
-    % Here, `Pendings` is a list messages that were pending delivery in the remote
-    % session, see `clean_session/3`. It's a replay context that gets passed back
-    % here after the remote session is taken over by `open/2`. When we have a set
-    % of remote deliveries and a set of local deliveries, some publishes might actually
-    % be in both sets, because there's a tiny amount of time when both remote and local
-    % sessions were subscribed to the same set of topics simultaneously (i.e. after
-    % local session calls `resume/2` but before remote session calls `takeover/1`
-    % through `emqx_channel:handle_call({takeover, 'end'}, Channel)`).
-    % We basically need to:
-    % 1. Combine and deduplicate remote and local pending messages, so that no message
-    %    is delivered twice.
-    % 2. Replay deliveries of the inflight messages, this time to the new channel.
-    % 3. Deliver the combined pending messages, following the same logic as `deliver/3`.
+    %% NOTE
+    %% Here, `Pendings` is a list messages that were pending delivery in the remote
+    %% session, see `clean_session/3`. It's a replay context that gets passed back
+    %% here after the remote session is taken over by `open/2`. When we have a set
+    %% of remote deliveries and a set of local deliveries, some publishes might actually
+    %% be in both sets, because there's a tiny amount of time when both remote and local
+    %% sessions were subscribed to the same set of topics simultaneously (i.e. after
+    %% local session calls `resume/2` but before remote session calls `takeover/1`
+    %% through `emqx_channel:handle_call({takeover, 'end'}, Channel)`).
+    %% We basically need to:
+    %% 1. Combine and deduplicate remote and local pending messages, so that no message
+    %%    is delivered twice.
+    %% 2. Replay deliveries of the inflight messages, this time to the new channel.
+    %% 3. Deliver the combined pending messages, following the same logic as `deliver/3`.
     PendingsAll = dedup(ClientInfo, Pendings, emqx_utils:drain_deliver(), Session),
     {ok, PubsResendQueued, Session1} = replay(ClientInfo, Session),
     {ok, PubsPending, Session2} = deliver(ClientInfo, PendingsAll, Session1),