Is possible configure to prevent OOM Killer to kill oracle instance?

Dear,

This customer has used ODA x8-2 HA 19.8, DBMS 11.20.4 for production system.

Two DB instances is running on this ODA.

I heard they tried to upgrade DBMS from 11.2.0.4 to 19.8 version manually.

They suffered very low performance. So, this system was backup 11.2.0.4 DBMS using flashback to return original data status.

Since this occurred, main instance of 2 is reset on Node0 server by Out of Memory(OOM) Killer twice ( 1'st May and 16th June). At that time, same midnight about 03:30 AM, it seem low transaction. It was RMAN Archive job and copy RMAN backupsets external NAS.

I have two help to you;