Messages in this thread | | | Date | Mon, 16 Jan 2023 11:17:52 +0100 | Subject | Re: [PATCH 21/46] hugetlb: use struct hugetlb_pte for walk_hugetlb_range | From | David Hildenbrand <> |
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On 12.01.23 22:33, Peter Xu wrote: > On Thu, Jan 12, 2023 at 04:17:52PM -0500, James Houghton wrote: >> I'll look into it, but doing it this way will use _mapcount, so we >> won't be able to use the vmemmap optimization. I think even if we do >> use Hugh's approach, refcount is still being kept on the head page, so >> there's still an overflow risk there (but maybe I am >> misunderstanding). > > Could you remind me what's the issue if using refcount on the small pages > rather than the head (assuming vmemmap still can be disabled)?
The THP-way of doing things is refcounting on the head page. All folios use a single refcount on the head.
There has to be a pretty good reason to do it differently.
-- Thanks,
David / dhildenb
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