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[2003:d8:2f0c:c200:fa4a:c4ff:1b32:21ce]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4711441f66dsm43882315e9.2.2025.10.16.13.10.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Oct 2025 13:10:20 -0700 (PDT) Message-ID: <99d5c245-3b0f-4b33-8d44-bc2b203a5a51@redhat.com> Date: Thu, 16 Oct 2025 22:10:19 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Patch v2 2/2] mm/huge_memory: Optimize and simplify __split_unmapped_folio() logic To: Wei Yang , akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev Cc: linux-mm@kvack.org References: <20251016004613.514-1-richard.weiyang@gmail.com> <20251016004613.514-3-richard.weiyang@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: <20251016004613.514-3-richard.weiyang@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: L1jUmF4o0mgPBKZa_b2bmb9s_XbZEWVbNl_5F9vCFdQ_1760645422 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: kqjb4wib47t7qka88499ee8hr46bbd7y X-Rspamd-Queue-Id: D85171C0003 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1760645426-553376 X-HE-Meta: U2FsdGVkX18avDa1YMIoXv/U/r01iUQQ9KxtitppkloH/dKWwcocvYjmMohWyo9czwUden4ZicUewC4IJM08zvJV7SlmdQRQzHnO4zq5yUBMUl2Ltzmi/c1+KxXqXyM4O4xIbfbT9tjPoEF14laqG5co8pOq6OBLtp8QxFvGxgO5gGp38OCvV5SWG+QsPxqMX2MlPbGCWVdL2YWRnP0ETQryqRGwQnBIjzrwSZ9MBfGmNlOt4W7Lagk95PLsznAloDkOc+GNx0g+5cworMxgq0QGrGcNXh1KVCs5U4tQd0D2LBDga6Yr0xe3J0hegrizWsOZHPIubC0e7XyDt2u3taWXOh+sDjhAqdax4ydIlvKsPEkcig5CJ9eT80SZxg/F7PU8/mo2C83DdDkHoBE0iqTtcAjStul/uu75oFNaFTFf4D5t0PRobsiGcNc+DRl40bWlR5912BGQcTdTmKRZ79p2bjSsDnzcDs8zIPoalS+Frh/bV+37AKKF6aqri6qRu+4Ah4T4TXW8U3Uur5aGpn1FYviNeVVf1BOuVVCDrY/pxJue8N5SbZsoivV+eOKQWeqX4leKsgGOlHD59FqdZPnxyu2mlSzDiELTtvHUjgD/UDBbzkn8+3K9J4xJ5flswEjGssxm0TLX1HXipl8outupevBhz/KHMQMI4f/eXsJEjdihNipvHV2kLD4WRw62jdG/hS33nMVHAd5Snyo6fplK8c2eXCQN8cCgXhxqvVOTGWpfEEvcZsg6IRECtSK9xjXXXnxfSP+F+3R1fOI7wxBUABBZqjnN3Kml1xEFwVwzWUYVKyDByySTb+59GMcKFRNstGljMOla3bPNa6vJUl5hpUBy7quKcZO8aaN3dDyGP2G5R4glIYk0+E+JxTXyvYnP7Nc+G1+YstFntfFjRklR4BcETKNYu0dnXGaV+ydyfbYOpH9ipdnZozISwuPA7O4Q3iMoxs+MbMUp3cw CgvN5ht1 Ul63X3NJ3+cFk7vjIBMjeB8PCY+uHsLaCLHYeLJplhgDYN84R0AcWH8AAy+REcMCSKkSVHChLYrE6noTh9MZJnqZukyZAhWF/af/TNEokojCvrxSoVt7q3sFVeePMVfp66vJpYD3q7zLkpJ1HxP4dznIh1CXz14yzkIzP 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 16.10.25 02:46, Wei Yang wrote: > Existing __split_unmapped_folio() code splits the given folio and update > stats, but it is complicated to understand. > > After simplification, __split_unmapped_folio() directly calculate and s/calculate/calculates/ > update the folio statistics upon a successful split: s/update/updates/ > > * All resulting folios are @split_order. > > * The number of new folios are calculated directly from @old_order > and @split_order. That makes sense. > > * The folio for the next split is identified as the one containing > @split_at. > That as well. > * An xas_try_split() error is returned directly without worrying > about stats updates. Why is that change ok? > > Signed-off-by: Wei Yang > Cc: Zi Yan > Reviewed-by: Zi Yan > > --- > v2: > * merge patch 2-5 > * retain start_order > * new_folios -> nr_new_folios > * add a comment at the end of the loop > --- > mm/huge_memory.c | 66 ++++++++++++++---------------------------------- > 1 file changed, 19 insertions(+), 47 deletions(-) Skimmed over the rest and LGTM, but it's all a bit complicated to understand. Trusting on Zu Yan here :) -- Cheers David / dhildenb