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Shutemov" , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Mike Rapoport , Mike Kravetz Subject: Re: [PATCH RFC 06/12] mm/gup: Drop folio_fast_pin_allowed() in hugepd processing Message-ID: References: <20231116012908.392077-1-peterx@redhat.com> <20231116012908.392077-7-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: 8FD2D140024 X-Rspam-User: X-Stat-Signature: cd17iry8hho4cze89a5qdgippeztouti X-Rspamd-Server: rspam03 X-HE-Tag: 1700640029-963235 X-HE-Meta: U2FsdGVkX1/kMVF6UAT3rOHrk+ipD0S841aMZ2Ba9kdD2YZ+2RuavhZaWQTkOu4zYiilqgzWQusIx8qTh3XQ7bYVu+/YMq+jD+DMzfwp5sRIFsHT3UtXLbTpWcy26XoCxptXltmW5+pPdtzzrJnM70bHjsdfHYuThj7RYdHwUV0bbZLw9lf7gVXhHY7UYEn3jGWa4BkZVdPBxtbTxlubAA2uTnThO9TpsppmjOORK0vu/TD4x06C3dVvFn4LL+LN17HqchVHM+DKT2xIeCHhi/jRD77dmIePe7FOZHjGVmaj5ERlM4mVRx2Rv6IHaYgiLr0KDt+xFmvdfrtsG/Sobq9+ozlG0v5QITtlCw4KUzYjw1fge01kA4gf6DAtL85XrICouCbRChJWPhnZZN0EhXSxsa+0siB1n4eFh5lQzgw++PAciYE6odagtsKhfmzEZENFePXfxzOFelyHRwNgrvHdKHGQlyz1/MWWDuWctexGsrt79HtOr+BGeYqMy6L+704UqoeSmpdiC+x9nXS3RAPY0nHiFB7SWZUDK8VIIsEktWlASDcneP1vV1s70dkwvgp21xLW9fZ1gAF+C7m6hyDGYS3ZanuP5B9io/BRII67VGmtbXvuRR2C69ouUniG7WA6QPbHDfePRfUht5DL1dF3szLvFS6H5jt56gb7IDgTynwPfrqcQ3NKvudzMA1Vt4ZhOsFj02t3L3yrxPS5LNeADnHHiLexjD2TpQ36hU+RxBsNxBGy3T7aJen1130HdOGqilGxR6M3S+I2C2fQfbNotB0b18JPXpqjeQNSKw3c3EEapyHxS7Ct7O1g2wg1bgiQTfHALhsE7ou3w1qc5Yq3h67XzF/7a42CLvWZTgZ+kfVf8pBsUO3Sr7xnxHa3W7Sq0kuoVq+1fMHZDjmYl5QQojRFjllAmLoBjPBLTDVJ+zXP87zX006voduRzasZRIlGbctA3St5adPSZ1J 7/UionGP yOQjrDlf1NK9232wgG7MKp3soS3ianrD02jYbGMvE8E1rznx9LydtW8zTPMlL0e6wiPDM3sAjjbZ462RCdwD1N6luA3CoTQ904Y0P+YFIMXyqK67pZq/5CSjLz0ZetqnyVCw085+hFmikVzOYKqFMf29Ki2oH/+lX14wdIb1AqhxJIk7CS9VSibD3lSFt8gg0kAx9H7IPuzERzpyL/NmX99mya3YdgLPV+JfKUiVEIkDgoAtgzGdHvNVpJHzlIhT6j/55lGMqaroczmE89AMbFoo6abramtmqir/2fnHJgC94qqH2U8oBNa1iXqZSqgAMR0kGML/LPlx2Xbsph95W7Xgi2XBiSUx1Tgc7bJF4FXuz4x8QouP79yVaUHGPjiNq04PjVGuWemF9LFyTtek/US3Ljs/7kO3an7aRucZq4JocpW9C1MXqjP/0Nw== 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, Nov 21, 2023 at 10:59:35AM -0500, Peter Xu wrote: > > What prevents us from ever using hugepd with file mappings? I think > > it would naturally fit in with how large folios for the pagecache work. > > > > So keeping this check and generalizing it seems like the better idea to > > me. > > But then it means we're still keeping that dead code for fast-gup even if > we know that fact.. Or do we have a plan to add that support very soon, so > this code will be destined to add back? The question wasn't mean retorical - we support arbitrary power of two sized folios for the pagepage, what prevents us from using hugepd with them right now? > The other option is I can always add a comment above gup_huge_pd() > explaining this special bit, so that when someone is adding hugepd support > to file large folios we'll hopefully not forget it? But then that > generalization work will only happen when the code will be needed. If dropping the check is the right thing for now (and I think the ppc maintainers and willy as the large folio guy might have a more useful opinions than I do), leaving a comment in would be very useful.