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[149.14.88.26]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-426ce57d4bbsm29263452f8f.2.2025.10.15.05.22.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Oct 2025 05:22:25 -0700 (PDT) Message-ID: <86ab6678-94a3-4150-8847-4fad00e09452@redhat.com> Date: Wed, 15 Oct 2025 14:22:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] ksm: use range-walk function to jump over holes in scan_get_next_rmap_item To: Pedro Demarchi Gomes , Andrew Morton Cc: Xu Xin , Chengming Zhou , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20251014151126.87589-1-pedrodemargomes@gmail.com> 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 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: <20251014151126.87589-1-pedrodemargomes@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: sPUTWATLVxZ_w4HwVRi7xmWMPe08nZHSsL5Edmx5HFI_1760530946 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: z55q8dax68ah6a3qywx36zcmpawacci8 X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 479E440006 X-HE-Tag: 1760530949-877210 X-HE-Meta: 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 iuzmymTO 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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 14.10.25 17:11, Pedro Demarchi Gomes wrote: > Currently, scan_get_next_rmap_item() walks every page address in a VMA > to locate mergeable pages. This becomes highly inefficient when scanning > large virtual memory areas that contain mostly unmapped regions. > > This patch replaces the per-address lookup with a range walk using > walk_page_range(). The range walker allows KSM to skip over entire > unmapped holes in a VMA, avoiding unnecessary lookups. > This problem was previously discussed in [1]. > > Changes since v1 [2]: > - Use pmd_entry to walk page range > - Use cond_resched inside pmd_entry() > - walk_page_range returns page+folio > > [1] https://lore.kernel.org/linux-mm/423de7a3-1c62-4e72-8e79-19a6413e420c@redhat.com/ > [2] https://lore.kernel.org/linux-mm/20251014055828.124522-1-pedrodemargomes@gmail.com/ > Can you also make sure to CC the reporter. So you might want to add Reported-by: craftfever Closes: https://lkml.kernel.org/r/020cf8de6e773bb78ba7614ef250129f11a63781@murena.io And if it was my suggestion Suggested-by: David Hildenbrand Not sure if we want a Fixes: tag ... we could have created gigantic VMAs with an anon VMA for like ever, so it would date back quite a bit. Please make sure to thoroughly compile- and runtime-test your changes. -- Cheers David / dhildenb