MDEV-35086 Trying to lock mutex when the mutex was already locked (session_tracker.cc), server hangs

followup for 9021f40b8ebf

mysql-test/main/session_tracker_sysvar.result

@@ -28,3 +28,12 @@ drop table t1;
 -- last_gtid: 0-1-1002
 
 reset master;
+#
+# MDEV-35086 Trying to lock mutex when the mutex was already locked (session_tracker.cc), server hangs
+#
+set session_track_system_variables='*';
+alter table t1 nowait force;
+ERROR 42S02: Table 'test.t1' doesn't exist
+use mysql;
+set session_track_system_variables=default;
+# End of 10.5 tests

mysql-test/main/session_tracker_sysvar.test

@@ -18,3 +18,14 @@ drop table t1;
 
 --disable_session_track_info
 reset master;
+
+--echo #
+--echo # MDEV-35086 Trying to lock mutex when the mutex was already locked (session_tracker.cc), server hangs
+--echo #
+set session_track_system_variables='*';
+--error ER_NO_SUCH_TABLE
+alter table t1 nowait force;
+use mysql;
+set session_track_system_variables=default;
+
+--echo # End of 10.5 tests

sql/session_tracker.cc

@@ -433,6 +433,7 @@ bool Session_sysvars_tracker::vars_list::store(THD *thd, String *buf)
     if (!*node->test_load)
     {
       mysql_mutex_unlock(&LOCK_plugin);
+      mysql_mutex_unlock(&LOCK_global_system_variables);
       continue;
     }
     sys_var *svar= node->m_svar;