Gosh, you’re likely right, but what if comparing the blocks (to decide on deduping) is a byte at a time and somehow that can be detected (with a timing channel or a uarch side channel)? Zfs likely compares the hash, but I think KSM doesn’t use hashes but memcmp (or something in that spirit) to avoid collisions. So just maybe… just maybe GP is onto something.. interesting fantasy ;-)

Thanks for putting meat on the (speculitive) bone I threw out! Very interesting.