[AstralStorm]

Ulimit is per process, it won't do. vm.overcommit_memory=2 with some setting of vm.overcommit_ratio or bytes will help though.

I'd say overcommit heuristics break applications and cause them to eat too much memory since they don't know when to stop. The only trouble is KVM which for some reason takes double of process space allocated to the VM for no good reason and perhaps memory intensive Java.

You need to tune the latter anyway.