I'm not entirely sure, but I'll apply the technique for my open source storage system. I have reference-instances with a log-key, persistent-key (file offset for instance) and will (re-add) the Java object references. In order to set them to null when the page is going to be evicted from the buffer cache I'll add a simple in-memory map with the proposed child => parent mapping, such that I can set the in-memory page reference to null again.