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[80.187.83.189]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46fb492e6ddsm204393555e9.0.2025.10.13.05.33.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Oct 2025 05:33:27 -0700 (PDT) Message-ID: Date: Mon, 13 Oct 2025 14:33:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC RFC PATCH] mm: convert VM flags from macros to enum From: David Hildenbrand To: Lorenzo Stoakes Cc: Ye Liu , Andrew Morton , Ye Liu , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20251011093054.886460-1-ye.liu@linux.dev> <809f552d-3282-4746-ba49-066d2bd8d44f@lucifer.local> <7ca0960f-9d1a-4ba4-b074-a6502578b82e@redhat.com> 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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: AGfkxQLGpeFDnZnEEaNhUd_4jBlDSTEkkJaxlxMzWpM_1760358809 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: BFDB718000C X-Stat-Signature: gzxpw89or3pyg93hsejeqm7nzcjqib7x X-Rspam-User: X-HE-Tag: 1760358811-508707 X-HE-Meta: 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 EKcFXpFq UgPFzmNr0Fmbbped0P8h6XLbKkmDDVQR3Ue73Ufaa27YCN597/mnEiMWySyElqdnpkppLsbaumP8PvI1zDEvoix6WYyLCDd5XWGbClV1s9eXpOEYxqatgqXIo6D6c64f0ZvpFSz6W1dpXtvZg+AXANd+HM5FM3swv2grbNHkhbYF6r7Ec+FKYndSk0nBT0iOhAYT02XNGADL6Knc8HGYxvtfPRixV8rWLAw0xkdCmFBzAAB2Xx0ilsYP8fZr5orSX3RsInu4v7x2cFr67tPDIEwaqGl0rz+gkPT77SlEkoOXWj6bYcuednjQ25LSop4XOhMuH6uZ+UeMIVb9VEcnyew7Fj/Ky5iHaj9fUaaPZIvFmTje2M890f9Sxkl51cVOG27rIWWqyC/GmhzqsU5PtHY5cAljWzrm7vJ413ndJlQiwFyuLobz3e3PRVY06gGeM3Ven3ocSNjn3Ij0D2wMlk6K+63XzQPzEnANN 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 13.10.25 14:31, David Hildenbrand wrote: > On 13.10.25 13:33, Lorenzo Stoakes wrote: >> On Mon, Oct 13, 2025 at 01:12:20PM +0200, David Hildenbrand wrote: >>> On 13.10.25 13:04, Lorenzo Stoakes wrote: >>>> On Sat, Oct 11, 2025 at 05:30:52PM +0800, Ye Liu wrote: >>>>> From: Ye Liu >>>>> >>>>> Hello MM maintainers and drgn community, >>>>> >>>>> This RFC proposes to convert VM_* flags from #define macros to enum >>>>> vm_flags. The motivation comes from recent drgn development where we >>>>> encountered difficulties in implementing VM flag parsing due to the >>>>> current macro-based approach. >>>> >>>> This isn't going to work sorry, it's not valid to have flag values as an enum >>> >>> I don't follow, can you elaborate? IIRC, the compiler will use an integer >>> type to back the enum that will fit all values. >> >> switch (flags) { >> case VAL1: >> case VAL2: >> etc. >> } >> >> Is broken (compiler will say you cover all cases when you don't...) > > I assume you mean theoretically, because there is no such code, right? > >> >> An enum implies independent values that exhaustively describe all state, however >> these flag values are not that - they're intended to be bit fields. >> > > Observe how we use an enum for FOLL_* flags, vm_fault_reason, fault_flag > and probably other things. > > But more importantly, > > enum pageflags { ... :) Okay, that one is different, because it's the actual bit numbers today. -- Cheers David / dhildenb