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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org Date: Wed, 22 Jul 2026 13:33:33 -0400 In-Reply-To: References: <20260717170036.743149-1-riel@surriel.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-Queue-Id: 0D0141C0010 X-Stat-Signature: c85jsxy5zgmwano9s9ek15of3ispxt4x X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1784741656-76408 X-HE-Meta: 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 Q5xgI/A7 auL0dkIiQdF4FusIFufkAoAkdxBMs/r98Q1Ao8xVJ6esLFlqxQV7hcYZGzucAXlxgHhkwCvayG+NAo8b6uFG1YlkFqUeR/Uwzfu9YpdS4kal87Qx8ztyB/kX/46k6f5aJyVmz1iRMzAu9lqBUC/k1V0Kzs/QWOT69V//OGEwPePQQvMm4V13JMzyNo68khy87VL5EmjbnNk/R2SVN6L4qvAEK8+4rlA8Jo1We Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 2026-07-21 at 20:12 +0200, David Hildenbrand (Arm) wrote: > On 7/17/26 19:00, Rik van Riel wrote: >=20 > >=20 > > get_user_pages_remote() does not fit: it hard codes the mmap lock > > and > > re-derives the VMA. get_user_page_vma() walks the page tables, > > faults a > > missing page in, and returns it with a reference and the caller's > > lock > > still held. >=20 > Agreed, and that can be tackled later. I'll stop making this series (much) bigger, then ;) I added a few things for v4, but I can save other stuff for follow-ups. >=20 > >=20 > > The per-VMA path also closes a pre-existing gap. A COWed page in a > > VM_IO/VM_PFNMAP VMA has a struct page, but the old code routed it > > to > > ->access(), where generic_access_phys() ioremaps the PFN and > > ioremap of RAM > > is rejected, so the read came up short. >=20 > Yep. The GUP code rejected VM_IO/VM_PFNMAP for, though, because it > did not > properly handle vm_normal_page_pmd() etc so far. >=20 Do we ever do a PMD sized COW on VM_IO / VM_PFNMAP VMAs? In other words, is this something we should: - leave out for now? - fix now? - fix later? If we can fix it later, I'll add it to the list. --=20 All Rights Reversed.