If you go that route, you should be able to avoid the code/data distinction entirely; as data pages can also be completly backed by files. I believe the kernel already keeps track of what pages are a clean copy of data from the filesystem, so I would think it would be a simple matter of essentially pageing out the corrupted data.

What would be interesting is if userspace could mark a region of memory as recomputable. If the kernel is notified of memory corruption there, it triggers a handler in the userspace process to rebuild the data. Granted, given the current state of hardware; I can't imagine that is anywhere near worth the effort to implement.