1. Initially map the not-yet-written page to a read-only page full of zeros (the same one for all allocations: only one exists in the whole system).
2. When a write takes place, copy-on-write clone that page to a newly allocated zero-filled-page, then allow the write to proceed.
1. Initially map the not-yet-written page to a read-only page full of zeros (the same one for all allocations: only one exists in the whole system).
2. When a write takes place, copy-on-write clone that page to a newly allocated zero-filled-page, then allow the write to proceed.