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nUgwSVnJ0XpQRID6z8DDwQCZqEZlEmMxpd6acwz/RK1wDovhx4jqenjI0zItD5G4j4xjd79vrR1KHVvO/bPSn6vpws0yKKyKb8aLcQUp+NBHuqCk4JL9pXKGdjf2kGKv8goag+TEZiggN8auzr6+1h13QbxZJI+ImCvPthdi2P8LtuDBsCVEsNKPCB5VW3bYnQjiZ92KJyZi8WpTQ1YqNgWV6YksBKni64sZ9Pr4C9G0PT8tFy4iFn0iUgzlAOO6IC8cxS1hrdgXvo4DuQ7lb78iemP8+nT/8hU86nfpnjo3OdtUsXUZoWwCJcv2xWYIMfXbU5KTnNC32mT4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 24 Feb 2026, at 14:03, Johannes Weiner wrote: > On Thu, Feb 19, 2026 at 03:53:35PM +0000, Usama Arif wrote: >> Why 1G THP over hugetlbfs? >> ========================== > > I know this isn't your intention, but one interesting aspect of > supporting PUD mapped folios natively is that it could open the door > to simplifying hugetlb as well. > > We currently have all kinds of huge_vma checks scattered over the page > table code, and entirely parallel paths for unmapping etc. With native > PUD mappings, this could allow pushing the special casing out of the > virtual memory layer and into where we deal with the page objects. > > You might be able to take it as far as the only thing left of hugetlb > is the reservation pool. Such that a naive application does mmap() as > per usual, and it comes down to a separate allocation policy how the > backing pages are served (buddy, CMA, boot-time reservations, ...) > > Approaching it this way could help separate out the discussion on code > impact and tech debt of PUD mappings, from the allocation technique > question, which in itself is a fairly large topic. I agree with this 100%. Adding 1GB folio support first, we then can think about what other THP features, e.g., split, migration, PMD/PTE mapping, are really needed and add them one by one. It is also going to be a good way of retiring hugetlb special code. Best Regards, Yan, Zi