Patent of ARC(Adaptive Replacement Cache) is expired (patents.google.com)

Expires on 2022-12-06, but status is already expired: https://patents.google.com/patent/US7167953B2/en

But another patent exists: https://patents.google.com/patent/US20070106846A1/en

I'm not sure that we can already create a patent-free implementation of ARC. Does anyone know?

However, note that ARC's hit ratios are worse than constant complexity algorithm today: https://github.com/falsandtru/dw-cache

ARC does not offer much as a modern cache replacement algorithm, so it passing into the public domain is little more than a curiosity. Even in its day it didn't stand out as a better algorithm in real systems.