> On Aug 18, 2019, at 8:58 PM, Daniel Axtens <dja@xxxxxxxxxx> wrote: > >>> Each page of shadow memory represent 8 pages of real memory. Could we use >>> page_ref to count how many pieces of a shadow page are used so that we can >>> free it when the ref count decreases to 0. > > I'm not sure how much of a difference it will make, but I'll have a look. > There are a grand total of eight possible pages that could require a given shadow page. I would suggest that, instead of reference counting, you just check all eight pages. Or, better yet, look at the actual vm_area_struct and are where prev and next point. That should tell you exactly which range can be freed.
