There's also cgroup resource controls to separately govern max memory and swap usage. Thanks to systemd and systemd-run, you can easily apply and adjust them on arbitrary processes. The manpages you want are systemd.resource-control and systemd.exec. I haven't found any other equivalent tools that expose these cgroup features to the extent that systemd does.

I really dislike systemd, and its monolithic mass of over-engineered, all encompassing code. So I have to hang a comment here, showing just how easy this is to manage in a simple startup script. How these features are always exposed.

Taken from a SO post:

  # Create a cgroup
  mkdir /sys/fs/cgroup/memory/my_cgroup
  # Add the process to it
  echo $PID > /sys/fs/cgroup/memory/my_cgroup/cgroup.procs
  
  # Set the limit to 40MB
  echo $((40 \* 1024 \* 1024)) > /sys/fs/cgroup/memory/my_cgroup/memory.limit_in_bytes