| There are a lot of kinds of objects in the kernel that don't have |
| individual limits or that have limits that are ineffective when a set |
| of processes is allowed to switch user ids. With user namespaces |
| enabled in a kernel for people who don't trust their users or their |
| users programs to play nice this problems becomes more acute. |
| |
| Therefore it is recommended that memory control groups be enabled in |
| kernels that enable user namespaces, and it is further recommended |
| that userspace configure memory control groups to limit how much |
| memory user's they don't trust to play nice can use. |
| |
| Memory control groups can be configured by installing the libcgroup |
| package present on most distros editing /etc/cgrules.conf, |
| /etc/cgconfig.conf and setting up libpam-cgroup. |