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Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn Subject: Re: [PATCH v3 20/20] mm: stop maintaining the per-page mapcount of large folios (CONFIG_NO_PAGE_MAPCOUNT) Message-ID: References: <20250303163014.1128035-1-david@redhat.com> <20250303163014.1128035-21-david@redhat.com> <20251014122335.dpyk5advbkioojnm@master> <71380b43-c23c-42b5-8aab-f158bb37bc75@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <71380b43-c23c-42b5-8aab-f158bb37bc75@redhat.com> X-Rspamd-Server: rspam01 X-Stat-Signature: ghbiu1x41cnuxgex4m8kn3pcdiuh7ur9 X-Rspam-User: X-Rspamd-Queue-Id: 1F1761C0006 X-HE-Tag: 1760452366-826863 X-HE-Meta: U2FsdGVkX19ZtIp51JoQicuh1TXpaipTeDBdOHMRiNycAswSp+KjRWOjDqp2JuWP5kYLg42Idm+hlGbl9PZ698v1oo+cF1ATIjQ4YGmfXuhGujWacRQbDFESlHPDMbxrc668JFcUf/Dg8jNuesPTeT8YWQ52FVagsYG78uYtG2pJHtmStjB1y5ICTUcZrzPk1KLU4gLVbEIZlFy3eOuKJNYn9rVGruOZ/ZQ5migoLJmddBrrHFh3vFf29IZEA8UQ7+ML6VZkU+B8wXwbPwx0kZSCCzQw+imxZRQqnhUubCVsondRL1B6oY0BqOh/jaXmJYzWVfIds6ASg0/eg0uMmzpM/oeTAau6cEzAdsoPOYdQlGviM3T/3MqfDuSq3Utizmph+l7nMREVuZFjOOjQoijnUpuAUDAEyTnnYUhtI1Nuf2Da8firnyRO3DigIK177vjEdazaaabjlaURz1J+ICUwmOYq4WPjlSZvqScMleN+a/hjKPfhYfzQvJhPX8pcr5GEdtdGGtkKjmWZN7ZzqbER9AQAiCu35+N7c9Ei8yDwdRCbEzvxtVtUUZq0eroTXMJQM3wILT2Ns/dabei5Zdgl+PqwHier4ggyvLfqhHEPrTInOkFKewZKVIH4W4Ek8t4ez0Cnm+yodbcv0p7gYYby/pTpMql4WRO590e1IplS8BgmtqZcgMEeS+2XkN8xLBrAF+3TayvX1TOx3HYoxzMy/OQ8EnjQ6T+H/LNw20utu8rrL7x2H4+67fjS9nZlZ6srXr6T4h08QzM3TJjVoVWFmMXDnt8yxusJJg84hm4HtLngBfsjhvcltnMFoEoZ58HpToinKUEG4sfxh9GOK2rxSWo5G0n+eYe/k5g/bjZDyeGlqnKTbkI+k0771+0kvk8XAj6hqxDNHRY7Fxiy3gFZRfQTnf/OFDbDsGMLq9cv+7caa2oRa7IZW6FP55S0lmc3wZ2y1n7Sav8xQhG jwdXd5JO qQ7hk 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 Tue, Oct 14, 2025 at 02:59:30PM +0200, David Hildenbrand wrote: > > As commit 349994cf61e6 mentioned, we don't support partially mapped PUD-sized > > folio yet. > > We do support partially mapped PUD-sized folios I think, but not anonymous > PUD-sized folios. I don't think so? The only mechanism I know of to allocate PUD-sized chunks of memory is hugetlb, and that doesn't permit partial mappings.