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b=RRt88J9DmanaTCYmIeioy7qKoeGnTjl9AMkGELq2T4pH+GfA72gsbE9WEq+qvtSQb 6kwBnjIxWXd5bUZ27qfGgvXpPJRc5y5L9jHfdxlCTI4Fensk3Da11x5gkQrtvkUmks 7+KtesJFqfnJVKXyKcJWEFycLgrTec23LCvhfh2q1P7RvfgD3ipkEPuDVguWl8TSBM pv+m4exVrr5/nFZ3W8U8Y/OPJdVxcxLvhXAwaJaIpqTv5tqOtqy2fH1bZNYlc51bJ1 mb8u84DGZuTtlpuph8ptRSv/OQvXj2jssWC9XIzxZxmW/XfTiyZUIJIr+Y3tX1Y3qg kY7cEWviwvmyw== Message-ID: Date: Wed, 16 Sep 2026 08:37:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/14] mm/ksm: merge-path cleanups and folio conversion To: Longlong Xia , Matthew Wilcox Cc: Andrew Morton , linux-mm@kvack.org, Longlong Xia , Xu Xin , Chengming Zhou , linux-kernel@vger.kernel.org References: <20260915222545.5683-1-xialonglong2025@163.com> 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: <20260915222545.5683-1-xialonglong2025@163.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: hxp96rhd4f8obk59hstuuuhs78k46syt X-Rspam-User: X-Rspamd-Queue-Id: 6DE13180002 X-Rspamd-Server: rspam03 X-HE-Tag: 1789540635-596555 X-HE-Meta: U2FsdGVkX1+ODI1R0gfQeTRAYkW/A5Zr3oUUNx1zpY9Yz2D7C3cJjty8974f/HhdlwBZUK0Q6cfDwlIZ/LVh6il2n7IxBZ3kxwhUqSMxo1KOvdilazB8r8DJw43N/RguMTMycSuSZqETXBGMlqwNYTF0FgOq9h+0rqjEq8airKcxXh9SFwDGRCGOn6PjjzBu8EaPB1Mlk7WFXqa3KqI1gSa2pvmLfXlGZBR3JHDNA0fp02IY5mRrtSznFci88XYKX3+kPiW251r6/qb2xtjwd/TENzb4PTLunisuxxNAF7pKU0zUPqQrUpvr8br90vfuNh01AuvHofEhm2xOw61s7olxXu+i/pfNnA7VaOCbZin+1oQgQ+/3ePak6UJdecFTLLUQivHpcpFXkf1fdD58BqIWCG7B0FrskGSH1EvfoEtXNV0VXcYTQ6LoXWabFHrUJ8kcGqqE/QsxkPBkJ9yK3CgVHLYrRoL7dQ3sH4nZUZQ7BbxbeapAj6+7Z2ZgQW/u2o8X4xAICJZewWMuJRxoKUfUujd/YrNZeyFIQhKwCJyTxysZa1XPWeciS/rAWNn4EpYGKX/N5FV2j52Kp4BxtTIkd0YeQk/Akw3EvNg3Qj8GIJpSut+NgbMOfyko41mdUUAA37kRkd1Gr/zgNS+8U7eSpd7gY2rJIAy9iilQDf/4nYGRlR+AwIHKLNDwLsYghuSNAD1zfP6peH+u6W7GEhwljNCzJWkrlbvGP7VSbdDAWgfN+vYOGWPDmPSoM/wchWawzbtHzTlzZuAk3f3IZzWNUaYXqT3Iw5dQHFiL15+IEFSHqaMG7R+wDIIThjlp7ub7xzHmQ+3HyxWQ3mcKKGossqXAez45gNJc/v3/hBIDyoRxAgGeUhxrsjHGGuO0Y/IK+sbMpJRCZDFpxrn1HTvmR4jYdj+4sLbbxoXQvmEkE83D6vlkKhOOvsgg4roJawJx+ZCUZ2mndPTDWkh RCmJH6zb YIp71fWpZ6mieKV1/OMcaLBC98Z8WIlgmhOKrqZc6GBq82scNL3ABE+d0sRPCh/c7rT4aqlFANEafKxyfmhZKOzhvp1Xv5YzDDMk+K4tRwn4bp7d5A1k1rqBaFt6PqoFJ9pg+3R4m69o3YOStR20bGqjF/qXMI3B/TVBo9Q93uLrXfMHcivHaANoFVyr37cVAyEspmPv0DinrwbLyFM5CCJiv5luv+ZU2Okif5NRB8JGl/1/LZpSMnOT0IZ6XMkdew2Df Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/16/26 00:25, Longlong Xia wrote: > Thanks for the review. You are right that I did not justify the > page/folio boundary clearly enough. > > Patches 11-13 only avoid converting the target page back to a folio and > provide no functional or performance benefit by themselves. > > I will separate the independent cleanups and drop or rework 11-13 after > getting guidance from the KSM maintainers. I also found a NULL/bisectability > issue in v1 patch 12, which I will fix before any follow-up. In general: once we have a ksm folio (folio_test_ksm()), it can only be a small folio and we can operate on the folio only. Until that point, we really need the page, because we might be dealing with a page in a large folio. Sure, we can carry a folio+page pair to reduce repeated folio lookups, but be aware that we have to re-lookup the folio and take care of references whenever we call into something that could end up splitting the folio. So we have to be a bit careful around that. -- Cheers, David