Mariadb 10.2 possible memory leak

Hi, i have a production database,
after upgrade 10.1 -> 10.2, i have a slow memory leak,
i'm not sure why i have problems with memory leak.
I use both InnoDB + TokuDB:
innodb_buffer_pool_size = 512M
tokudb_cache_size = 4096M
(I have 100+ GiB of data in TokuDB)

For 10.1 that restrict memory usage to ~5.5GiB, for 10.2 memory usage grow slowly unbound.
May be i miss some new config or how can i investigate that?

Thanks!