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b=sZEb6K2YedoHePpZc1igvCSBfZNBrGJBi8jQLbBUY2nThD+L/3S8D9jqg17V76XK6 FSM2oQQMeno2AKFYtifyrgLOfCZDthPUxHTWx8eZvyyDrqzkk2Hrec75AZN9qsVAwa UMG9lre442aR/vAZD6Xuug6/4fzcx9l4wR+eOhpIKLjS9h1nzotoIZ5QDBClDpEmcm LVGaHGK7CXXiOcgZKSicJhfNM2qk0bu+yhtViubdsNc8fyQu3Vsr3PFQPOiFZCJYIf RDiUHxvHBV8BpypAMXbUQDMjWAZkjHe6asgWo9C7IPUOV2FMkDgmseugS+orIIQZow AHur9V0RknTsA== Message-ID: <65d11b12-5696-4403-8062-3ae65ca9113e@kernel.org> Date: Mon, 18 May 2026 11:33:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm: introduce a new page type for page pool in page type To: Byungchul Park Cc: Dragos Tatulea , linux-mm@kvack.org, akpm@linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel_team@skhynix.com, harry.yoo@oracle.com, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, tariqt@nvidia.com, mbloch@nvidia.com, andrew+netdev@lunn.ch, edumazet@google.com, pabeni@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, ilias.apalodimas@linaro.org, willy@infradead.org, brauner@kernel.org, kas@kernel.org, yuzhao@google.com, usamaarif642@gmail.com, baolin.wang@linux.alibaba.com, almasrymina@google.com, toke@redhat.com, asml.silence@gmail.com, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, sfr@canb.auug.org.au, dw@davidwei.uk, ap420073@gmail.com References: <20260224051347.19621-1-byungchul@sk.com> <982b9bc1-0a0a-4fc5-8e3a-3672db2b29a1@nvidia.com> <20260513121805.GA22430@system.software.com> <8348d867-f8a1-432c-be2d-699ad96b2e93@kernel.org> <20260513123920.GA51788@system.software.com> <627bb280-be44-4648-8771-5a479cda988f@kernel.org> <20260513132636.GA75142@system.software.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1043A160007 X-Stat-Signature: 4jw8n7mi9womxpofxx8qq9gb73ngdkgn X-Rspam-User: X-HE-Tag: 1779096855-438100 X-HE-Meta: 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 ZAywtIHw VHO54j5ZPeCJBQrSoofCrGD+4QDR3kNlxTTTA2hHXxhOSN3CSbRk5bKvzLRwqaiWAnxeje7qT3Sv4Gd3Ayuk3/ouLQsUtochOOMAd/dem2gY1QARAvRqkKSP2EsfXM2eCfk2ZJKPgNpXGPYxBu/dli99Rs6OPUvQx3P92KPTRxZ0PbOm09/Lqc2iXCEhDzkVTLRx5gNQiO7a1Wngd3uHCCDtm33snRPEJNTT60WTTOMZMW1wi17OS8ECl1KGZj5vuWkTQAlrXE9MRUzxVG19yWy3acf6BlptP0/oxPQF05MbLn2pbRHkrfIP6yKXqJAiZHY1/UHZ/VJ+DjR2lmVWy/I/UgpxTXuE/a26J+U77B5b/KpFB66RJVgw/vQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/13/26 15:26, Byungchul Park wrote: > On Wed, May 13, 2026 at 03:02:43PM +0200, David Hildenbrand (Arm) wrote: >> On 5/13/26 14:39, Byungchul Park wrote: >>> On 5/13/26 14:18, Byungchul Park wrote: >>> >>> This is not final patch, but for sharing the rough idea *with code* - >>> maybe there are more points in code that should be adjusted by the >>> change. I just typed the draft patch quick just for sharing idea. >>> >>> If we should allow pp type pages to be used in mapping as well, then >>> we should allow a page to keep both its type and mapcount at the same >>> time. Am I missing something? >> >> We don't want code to accidentally overflow mapcounts into these bits and have >> them wrongly be detected as page types. >> >> This is just very fragile. > > Okay. Thanks for the explanation. Plus, the adjustment I mentioned > might not be as simple as I thought it'd be. > > So sorry about the noise. I'm a zombie now. I'll think about it after > some rest. It's a shame we didn't get reports earlier that we do have some vm_insert_page() users :( -- Cheers, David