[How] do you track when it's safe to delete the old version of a patched piece of code?

Edit: or, I guess since this doesn't seem to be something intended for use in prod, maybe that's not necessary. You can just bloat the runtime process more or less indefinitely.

I was curious because IIUC Linux kernel livepatches handle this via something related to RCU, which I guess is not possible in this context.