Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 19 Aug 2019 15:20:47 -0700 | Subject | Re: [PATCH v4 1/3] kasan: support backing vmalloc space with real shadow memory |
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> On Aug 18, 2019, at 8:58 PM, Daniel Axtens <dja@axtens.net> 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.
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