How to cope with hardware-poisoned page-cache pages

The behavior in the event of a crash is indistinguishable from the behavior where the RAM works correctly, but the page fails to get written out before the crash happens (i.e. the data is lost either way), so arguably this is no worse than the (unfixable) status quo. That's assuming, of course, that the application does not call fsync(). If the application does call fsync(), you can at least return EIO, but then the application is a bit screwed because it's unclear exactly what data got clobbered or what the application should do to recover from it. Also, not everybody remembers to check the error code from fsync().