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Tsirkin" Cc: linux-kernel@vger.kernel.org, Andrew Morton , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , linux-mm@kvack.org, virtualization@lists.linux.dev, Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Johannes Weiner , Zi Yan References: <2155527a-e077-4b71-80ee-d735f9984f60@kernel.org> <20260413163233-mutt-send-email-mst@kernel.org> <244c9779-b4a5-4d0f-9eb9-ef0ec873e0f6@kernel.org> <20260414062015-mutt-send-email-mst@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+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: <20260414062015-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 87A252000F X-Stat-Signature: yc5afj7snwbtgcq438dz9tky9fq11cgk X-Rspam-User: X-HE-Tag: 1776180744-594211 X-HE-Meta: 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 lmN6CW5c DG7rwJ2pTkZXjkiuH5WfwVxyow/SdcOrDy3gnTdR4Ip6wcIwK4powxVReJgiQtjxVnqjOSyyn+hAUw/ZURnyzSX74w5rHoWwoL0lAQWoNP6uWihyaJb7sZICbbOs8A5BOHhk5DdaB5gZa7squLzyZvBfLzaN8P5uOow40k/j/OIuio6dQq4q0tJkzh3nA0Jr9hcDNXspoEeDSqaD35iWvK0pnUXSVm/4M/eRi+4k2jNF+35RxAyEv0cW+/iTESXVk3WOPLuY3Rym3+7Thmqayc6ny/AZCUyjlx1f9r3/5nxFVji4K0AyR6PjKiQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/14/26 12:22, Michael S. Tsirkin wrote: > On Tue, Apr 14, 2026 at 11:18:02AM +0200, David Hildenbrand (Arm) wrote: >> On 4/13/26 22:35, Michael S. Tsirkin wrote: >>> >>> >>> So here's an only alternative I see: a page flag for when page is in >>> buddy and a new "prezero" bool that we have to propagate everywhere >>> else. This is a patch on top. More elegant? Please tell me if you prefer that. >>> If yes I will squash it into the appropriate patches. >> >> I'd be interesting to know how this would look without the GFP flag, >> when we don't have to leak any of this out of the buddy. >> >> -- >> Cheers, >> >> David > > But the zeroing takes place outside of the buddy now, it's more > "reporting" than "leaking". Exposing some buddy internals using questionable GFP flags, however you want to call that hack ;) > > You mean, moving the zeroing into buddy? Yes. Such that it doesn't really matter how we maintain this information internally. A page flag is probably still nicer for that purpose. -- Cheers, David