One of possible use cases that reproduces the memory leakage listed below:

  set timestamp= unix_timestamp('2000-01-01 00:00:00');
  create or replace table t1 (x int) with system versioning
    partition by system_time interval 1 hour auto
    partitions 3;

  create table t2 (x int);

  create trigger tr after insert on t2 for each row update t1 set x= 11;
  create or replace procedure sp2() insert into t2 values (5);

  set timestamp= unix_timestamp('2000-01-01 04:00:00');
  call sp2;

  set timestamp= unix_timestamp('2000-01-01 13:00:00');
  call sp2; # <<=== Memory leak happens there. In case MariaDB server is built
                    with the option -DWITH_PROTECT_STATEMENT_MEMROOT,
                    the second execution would hit assert failure.

The reason of leaking a memory is that once a new partition be created
the table should be closed and re-opened. It results in calling the function
extend_table_list() that indirectly invokes the function sp_add_used_routine()
to add routines implicitly used by the statement that makes a new memory
allocation.

To fix it, don't remove routines and tables the statement implicitly depends
on when a table being closed for subsequent re-opening.