Wouldn't the performance impact be that of setting the page read-only when the request is submitted, then doing a copy-on-write if the user process does write i

Wouldn't the performance impact be that of setting the page read-only when the request is submitted, then doing a copy-on-write if the user process does write it? I mean, that's nonzero, TLB flushes being what they are. But they do happen a bunch anyway...