Make sure to enable memory and cpuset cgroup in v2

Author: nickygerritsen

doc/manual/install-judgehost.rst

@@ -179,8 +179,8 @@ Optionally the timings can be made more stable by not letting the OS schedule
 any other tasks on the same CPU core the judgedaemon is using:
 ``GRUB_CMDLINE_LINUX_DEFAULT="quiet cgroup_enable=memory swapaccount=1 isolcpus=2"``
 
-You have now configured the system to use cgroups. On systems with
-cgroups v1, you need to run::
+You have now configured the system to use cgroups. To create
+the actual cgroups that DOMjudge will use you need to run::
 
   sudo systemctl enable create-cgroups --now
 

judge/create_cgroups.in

@@ -12,7 +12,8 @@ CGROUPBASE="/sys/fs/cgroup"
 # We do not need to do any of this with cgroup v2.
 fs_type=$(awk '$2 == "/sys/fs/cgroup" {print $3}' /proc/mounts)
 if [ "$fs_type" = "cgroup2" ]; then
-    echo "cgroup v2 detected, skipping cgroup creation" >&2
+    echo "+memory" >> /sys/fs/cgroup/cgroup.subtree_control
+    echo "+cpuset" >> /sys/fs/cgroup/cgroup.subtree_control
     exit 0
 fi