Error in forking cpimport.bin (errno-12); Cannot allocate memory

setup is a single node mariadb 10.5.4 with columnstore 1.5.2

during and ETL job sequentially chaining insert-select bulk load statements, we can see memory usage increase until around 90%
Then statements fail with the error : Error in forking cpimport.bin (errno-12); Cannot allocate memory

job is written in java, using a connection pool.

jemalloc fix has been applied already
Innodb buffer pool is 25% of total server memory.
TotalUmMemory + NumBlocksPct is 75%