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(p200300d82f438900f36413332a67d49e.dip0.t-ipconnect.de. [2003:d8:2f43:8900:f364:1333:2a67:d49e]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4563b740c51sm16819475e9.19.2025.07.18.04.06.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 18 Jul 2025 04:06:32 -0700 (PDT) Message-ID: <889dade6-8b3d-4cce-93ec-827886f7cb2c@redhat.com> Date: Fri, 18 Jul 2025 13:06:30 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 8/9] mm: introduce and use vm_normal_page_pud() To: Lorenzo Stoakes Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, xen-devel@lists.xenproject.org, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, Andrew Morton , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Dan Williams , Matthew Wilcox , Jan Kara , Alexander Viro , Christian Brauner , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Jann Horn , Pedro Falcato , Hugh Dickins , Oscar Salvador , Lance Yang References: <20250717115212.1825089-1-david@redhat.com> <20250717115212.1825089-9-david@redhat.com> <4750f39e-279b-4806-9eee-73f9fcc58187@lucifer.local> <15adb09d-4cdb-435d-927d-0c648d8239dc@lucifer.local> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: <15adb09d-4cdb-435d-927d-0c648d8239dc@lucifer.local> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: H2d0Lc0-yEvde-ut7LMO8sjs5tHJfOaekFS3k7zjOwk_1752836794 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: 617rdm6wdb7gwnny54qswi9auuzfonst X-Rspamd-Queue-Id: BB114C0009 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1752836796-970796 X-HE-Meta: U2FsdGVkX1/HbPwMNPM/7pzYSsmpqRFyfrxnGGREvK6ev9sTG2SREGFyE07rNEqPI3hOIQ/L04ByB+8qaoNISnlJ/m8YrMTpkzDuiMsgHUz9HL3PogHnvzfBMOUuVqA1k30IOqYPWY4j930pmrIx2OxDzeoT75RalfoUsJ0cmaDVBARrPkpwlmGoj9BiPD1VwkK0ye8LDCVFQAt4JQnjoKwbPSMWW8mHRqol2TpQY5Wmm1xWcMp4m/dApiuw5eekVikS0Gr/+yooqfdG6ha32A3UNL8bpIKl3QAML2W3PedRn6LijfsGS9d+Jst9XJyStmDgOrF2OQtsrK8r0Obq90Jl1WAvzqLRH6FX9JgJ60lj+T5sYPJRO2lTHz3kv0gg+1ntjksrwfAP9sVQkAfqiDWCFbDEiveesvuZ/+3V1ANQElesvl2csotemsI61U1xSXE1WxHwM2PjaEtUpPM36O5dJrY0hHY/RBm6rNV+2gnCSlYgGFS0IOTsY6pJ4sZkJj6fY3JCgdwb+PQmiRyilyftitwEN/b2I41Yw7d9gSC7pwkxYSgC6C0MJo2Y8rkwfk/uL2+e7tVqQNEJS+j2C+/4oDp9bi1O+3ruemcO+ZVYs2PLkKW7EpVS5hY8mcrO7eLK0oTSwKUyEljkJFQevkm1pneU+ueMTW0UxSm+HmaTsiyvzfkxFrptLYlA9I6ucmVzIg1/ZXrTD0EBs8TxNhmzCeL8HGQIJrnnXIgeY0S/W7PIdJV3fY5302YQv4ixaEXl9j6uzq180h11A7EgMxZs5m077TLhCco2uoww94sDuvuWUXgK8XESHVkFDz4KUPM/dAdDdSS9lFkN5162ztAZP36jOIi9vnjr6Rn4RtGoEW7vjRlM/JkXmdka7b/NT1uMXdiNzGwGvBk1OA7zf1sEOR196RCI7+ZRigzXG7yU8e4NVJpEp5nA5tmpUK+aN3hFjPaL0pA8wd61ol1 8px0s6HK 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 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 18.07.25 12:47, Lorenzo Stoakes wrote: > On Thu, Jul 17, 2025 at 10:14:33PM +0200, David Hildenbrand wrote: >> On 17.07.25 22:03, Lorenzo Stoakes wrote: >>> On Thu, Jul 17, 2025 at 01:52:11PM +0200, David Hildenbrand wrote: >>>> Let's introduce vm_normal_page_pud(), which ends up being fairly simple >>>> because of our new common helpers and there not being a PUD-sized zero >>>> folio. >>>> >>>> Use vm_normal_page_pud() in folio_walk_start() to resolve a TODO, >>>> structuring the code like the other (pmd/pte) cases. Defer >>>> introducing vm_normal_folio_pud() until really used. >>> >>> I mean fine :P but does anybody really use this? >> >> This is a unified PFN walker (!hugetlb + hugetlb), so you can easily run >> into hugetlb PUDs, DAX PUDs and huge pfnmap (vfio) PUDs :) > > Ahhh ok. I hate hugetlb so very very much. > > Oscar is doing the Lord's work improving things but the trauma is still > there... :P > > Also yeah DAX ahem. > > I'm not familiar with huge pfnmap PUDs, could you give me a hint on this? :>) vmf_insert_pfn_pmd(), called from drivers/vfio/pci/vfio_pci_core.c Essentially, we create huge PUDs when mapping device BARs to user space. -- Cheers, David / dhildenb