====================================User namespaces and resource control==================================== The kernel contains many kinds of objects that either don't haveindividual limits or that have limits which are ineffective whena set of processes is allowed to switch their UID. On a systemwhere the admins don't trust their users or their users' programs,user namespaces expose the system to potential misuse of resources. In order to mitigate this, we recommend that admins enable memorycontrol groups on any system that enables user namespaces.Furthermore, we recommend that admins configure the memory controlgroups to limit the maximum memory usable by any untrusted user. Memory control groups can be configured by installing the libcgrouppackage present on most distros editing /etc/cgrules.conf,/etc/cgconfig.conf and setting up libpam-cgroup.