MariaDB server is using the more memory than specified in innodb_buffer_pool_size

i have 3 node cluster in once site each. in the secondary site, where data is coming from the replication only. i have innodb_buffer_pool_size=300G. i observed that mariadb is using 309G and also swap memory is also used by the mariadb sever. 23G is used out of 32G swap memory.

Please find attached my.cnf file as reference