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Howlett" , Mike Rapoport , Michal Hocko , Jason Gunthorpe , Peter Xu , Matthew Wilcox , Usama Arif Date: Tue, 28 Jul 2026 10:29:07 -0400 In-Reply-To: <510410af-dfb6-403a-a864-50afdeceb896@nvidia.com> References: <20260724222934.1463812-1-riel@surriel.com> <20260724222934.1463812-5-riel@surriel.com> <510410af-dfb6-403a-a864-50afdeceb896@nvidia.com> Autocrypt: addr=riel@surriel.com; prefer-encrypt=mutual; keydata=mQENBFIt3aUBCADCK0LicyCYyMa0E1lodCDUBf6G+6C5UXKG1jEYwQu49cc/gUBTTk33A eo2hjn4JinVaPF3zfZprnKMEGGv4dHvEOCPWiNhlz5RtqH3SKJllq2dpeMS9RqbMvDA36rlJIIo47 Z/nl6IA8MDhSqyqdnTY8z7LnQHqq16jAqwo7Ll9qALXz4yG1ZdSCmo80VPetBZZPw7WMjo+1hByv/ lvdFnLfiQ52tayuuC1r9x2qZ/SYWd2M4p/f5CLmvG9UcnkbYFsKWz8bwOBWKg1PQcaYHLx06sHGdY dIDaeVvkIfMFwAprSo5EFU+aes2VB2ZjugOTbkkW2aPSWTRsBhPHhV6dABEBAAG0HlJpayB2YW4gU mllbCA8cmllbEByZWRoYXQuY29tPokBHwQwAQIACQUCW5LcVgIdIAAKCRDOed6ShMTeg05SB/986o gEgdq4byrtaBQKFg5LWfd8e+h+QzLOg/T8mSS3dJzFXe5JBOfvYg7Bj47xXi9I5sM+I9Lu9+1XVb/ r2rGJrU1DwA09TnmyFtK76bgMF0sBEh1ECILYNQTEIemzNFwOWLZZlEhZFRJsZyX+mtEp/WQIygHV WjwuP69VJw+fPQvLOGn4j8W9QXuvhha7u1QJ7mYx4dLGHrZlHdwDsqpvWsW+3rsIqs1BBe5/Itz9o 6y9gLNtQzwmSDioV8KhF85VmYInslhv5tUtMEppfdTLyX4SUKh8ftNIVmH9mXyRCZclSoa6IMd635 Jq1Pj2/Lp64tOzSvN5Y9zaiCc5FucXtB9SaWsgdmFuIFJpZWwgPHJpZWxAc3VycmllbC5jb20+iQE +BBMBAgAoBQJSLd2lAhsjBQkSzAMABgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRDOed6ShMTe g4PpB/0ZivKYFt0LaB22ssWUrBoeNWCP1NY/lkq2QbPhR3agLB7ZXI97PF2z/5QD9Fuy/FD/jddPx KRTvFCtHcEzTOcFjBmf52uqgt3U40H9GM++0IM0yHusd9EzlaWsbp09vsAV2DwdqS69x9RPbvE/Ne fO5subhocH76okcF/aQiQ+oj2j6LJZGBJBVigOHg+4zyzdDgKM+jp0bvDI51KQ4XfxV593OhvkS3z 3FPx0CE7l62WhWrieHyBblqvkTYgJ6dq4bsYpqxxGJOkQ47WpEUx6onH+rImWmPJbSYGhwBzTo0Mm G1Nb1qGPG+mTrSmJjDRxrwf1zjmYqQreWVSFEt26tBpSaWsgdmFuIFJpZWwgPHJpZWxAZmIuY29tP okBPgQTAQIAKAUCW5LbiAIbIwUJEswDAAYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQznneko TE3oOUEQgAsrGxjTC1bGtZyuvyQPcXclap11Ogib6rQywGYu6/Mnkbd6hbyY3wpdyQii/cas2S44N cQj8HkGv91JLVE24/Wt0gITPCH3rLVJJDGQxprHTVDs1t1RAbsbp0XTksZPCNWDGYIBo2aHDwErhI omYQ0Xluo1WBtH/UmHgirHvclsou1Ks9jyTxiPyUKRfae7GNOFiX99+ZlB27P3t8CjtSO831Ij0Ip QrfooZ21YVlUKw0Wy6Ll8EyefyrEYSh8KTm8dQj4O7xxvdg865TLeLpho5PwDRF+/mR3qi8CdGbkE c4pYZQO8UDXUN4S+pe0aTeTqlYw8rRHWF9TnvtpcNzZw== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) MIME-Version: 1.0 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 8938680002 X-Rspam-User: X-Stat-Signature: ko8xzfki8bdr693ia9x8en7k6n45o651 X-HE-Tag: 1785249071-91909 X-HE-Meta: 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 x4NFYV41 Y+ig8Bt41bBUpzVSv8nIkPrTqFpbQWHfU7HAnEVZFXl2YPOXTlL5kgd2AJ3wYI7DMQmhJ39d0hI02nC7UZ4M8hXAyy+2oqjn6VVYq0bFum3LECmdZhJ8NLn34ZdZelrgoyth0OkICiLJPk4poJfFucjDqz0f04ijbl5I78JktyB/IBw9Fl4YtVToBRE+elaZz3oof2/Q0go1wx+Ex2X3k5QoAnPl6IK4Dcfr0PX9ozmmaiCeXh521j6h9kVCX4qjr6ckUZufMObELAm5xmkS6rAaGXw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 2026-07-27 at 19:40 -0700, John Hubbard wrote: >=20 > Perhaps it is best to replace the mask with a single-purpose internal > GUP flag, such as FOLL_PFNMAP_COW, and apply it only to the > special-mapping gate: >=20 > if (vm_flags & (VM_IO | VM_PFNMAP) && > =C2=A0=C2=A0=C2=A0 (!(gup_flags & FOLL_PFNMAP_COW) || > =C2=A0=C2=A0=C2=A0=C2=A0 !(vm_flags & VM_PFNMAP))) > return -EFAULT; >=20 > This permits the later caller to examine a VM_PFNMAP mapping while > keeping VM_IO-only mappings and every other VMA check unchanged. Nice idea. I will implement that for v5! --=20 All Rights Reversed.