raspi-config
has the ability to enable the Overlay File System so that no changes are saved to the SD card. That is fantastic, but it seems the changes are saved in RAM. The problem is, when the Pi runs out of RAM for all the changes, it acts flaky. Since I don't care about the changes I'd like to just periodically flush them, but I can't seem to make that happen. This system is headless, runs 24/7, and never reboots.
I tried mount -o remount /
(from this answer) but that doesn't seem to work.
How do I tell the overlay file system to forget all the changes without rebooting?