As the question you asked, I assumed you have searched about how to setup limitation for Memory in K8S -> https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/#how-pods-with-resource-limits-are-run
In this section you will know the limitation you set would be convert to docker command(if you use docker in k8s), spec.containers[].resources.limits.memory
-> --memory=""
and if you check the official document about kernel memory in docker -> https://docs.docker.com/config/containers/resource_constraints/#--kernel-memory-details
which hasnt mentioned in k8s document. So I assume the value should be the default value for different type of linux system.