app-admin/cgmanager is limited in functionality without CONFIG_USER_NS and CONFIG_PID_NS being set in the kernel configuration. From cgmanager.c: if (stat("/proc/self/ns/pid", &sb) == 0) { mypidns = read_pid_ns_link(getpid()) setns_pid_supported = true; } if (stat("/proc/self/ns/user", &sb) == 0) { myuserns = read_user_ns_link(getpid()); setns_user_supported = true; } And then various functionalities in the code depend on setns_pid_supported and setns_user_supported variables being true. Please add check for these kernel config items to app-admin/cgmanager ebuild so users know they should enable these options for full package functionality.