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[2003:d8:2f20:da00:b70a:d502:3b51:1f2d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3e760775842sm7308106f8f.7.2025.09.12.09.06.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Sep 2025 09:06:13 -0700 (PDT) Message-ID: Date: Fri, 12 Sep 2025 18:06:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 10/15] mm, swap: wrap swap cache replacement with a helper To: Kairui Song , linux-mm@kvack.org Cc: Andrew Morton , Matthew Wilcox , Hugh Dickins , Chris Li , Barry Song , Baoquan He , Nhat Pham , Kemeng Shi , Baolin Wang , Ying Huang , Johannes Weiner , Yosry Ahmed , Lorenzo Stoakes , Zi Yan , linux-kernel@vger.kernel.org, Kairui Song References: <20250910160833.3464-1-ryncsn@gmail.com> <20250910160833.3464-11-ryncsn@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: <20250910160833.3464-11-ryncsn@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: ug5gLv4zLX7ULqOk8IgvrIDaAQKwG5I4rKIjENt2lP0_1757693174 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: fcrbodzqhf4g5h8pij68mdwsiusqy11z X-Rspamd-Queue-Id: E8950180010 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1757693177-337548 X-HE-Meta: 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 X2qObNPY Y/9W7WV+0/gsOQ5qgYWgKBlCMH4ZFgnlQw1zl2sLiCuNtNwf7wE4TpKfsJgY/rJ1ZpiJKSmrZNQC40v2OgteCWoJkOWK5MmPoa8KD6FpBOm3AZzavLL3EG1gFsZEZSJ1TUSn0StwHld5lrgZ1TxQKNCl4fEYnIsqb2dSTusoCEcJqdD8G3CLGovI+Xbq1zPEjj379xqAOO87oRlmBQ0gyfgDZ1m9NSDeWaHYAlO05aUUw6OkfFSWCGde7MkOfshhuBPzSPHB4QOUSucj6a2G9QcVb2R7P3PxMgv6q4AvZ5huXuRTxD518jCIYYsVwoaI+WK66jvNbVj5Z9liVovrLTvRLx0IJtzA9uRol9n4uk1agSily4vnBQMpPhPOuxFdlu3ygiWAoPjJc9w28I8PA/9Bav579bzWgw7+AEp6weinX1wEN48x0MPKSgmi73GNxdqaLrP91jUGzUaE0pxVlIDF6Ug== 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 10.09.25 18:08, Kairui Song wrote: > From: Kairui Song > > There are currently three swap cache users that are trying to replace an > existing folio with a new one: huge memory splitting, migration, and > shmem replacement. What they are doing is quite similar. > > Introduce a common helper for this. In later commits, this can be easily > switched to use the swap table by updating this helper. > > The newly added helper also makes the swap cache API better defined, and > make debugging easier by adding a few more debug checks. > > Migration and shmem replace are meant to clone the folio, including > content, swap entry value, and flags. And splitting will adjust each > sub folio's swap entry according to order, which could be non-uniform in > the future. So document it clearly that it's the caller's responsibility > to set up the new folio's swap entries and flags before calling the helper. > The helper will just follow the new folio's entry value. > > This also prepares for replacing high-order folios in the swap cache. > Currently, only splitting to order 0 is allowed for swap cache folios. > Using the new helper, we can handle high-order folio splitting better. > > Signed-off-by: Kairui Song > Reviewed-by: Baolin Wang > --- Acked-by: David Hildenbrand -- Cheers David / dhildenb