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Howlett" , Nico Pache , Ryan Roberts , Barry Song References: <20250905141137.3529867-1-david@redhat.com> <06874db5-80f2-41a0-98f1-35177f758670@gmail.com> <20e7f812-c1e7-455f-a523-08fc99024adb@arm.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: <20e7f812-c1e7-455f-a523-08fc99024adb@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 7INa71Rxqme19Si0qg0nYo-kRy2VdLyURaxG8tu8P58_1757926310 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: C179640003 X-Stat-Signature: cngbhra4sjbraku357shwig887dkhzrj X-Rspam-User: X-HE-Tag: 1757926313-632831 X-HE-Meta: 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 h3Y544rM KNSXUQkgS5PktXNeze/mBrDst1pBqHbqJaJMU3BDc3hAXrPslk6BLuxyYwRHLo7UeV9XfEkvxRsl1JaNxNk978/VoOs2jkjiUNcLr4tXxMXwSWnxZv6lbd74Ann58YT++wk8651xj0xmIjb4Y3y6a3IniPSIMJlMM1yh/H7ozAT/NORldE8X42++sml8fepkWwBiQsSujN4Z5SFpIbnXQn2RB9ke4P2w+GVaNCECcdAE+keozpXdB0t3T849Z2IYbR2j9xFn1R2gtNtEXEHk+SDjqgSsjAgAqDanGDjYUI43PL7JD6UyIwAoDiD9qRHvSW2E38pXDvwJDkysmJ3IJJYrM3xvP9lUiM4ObPTYeMbS8jbnrilWCixKahdggR9HVVRJR2afuY1+A/swBnxMfVDNjW1JvtSlWICOhr8nbC+aIxt3fEdHktcJEltdCg2Ehr+7XcqRYpEYPPVBdq9Yek6P6F8VK3489uOYN 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 14.09.25 16:04, Dev Jain wrote: >>> --- >>> mm/huge_memory.c | 3 --- >>> 1 file changed, 3 deletions(-) >>> >>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>> index 26cedfcd74189..aa3ed7a86435b 100644 >>> --- a/mm/huge_memory.c >>> +++ b/mm/huge_memory.c >>> @@ -4110,9 +4110,6 @@ static bool thp_underused(struct folio *folio) >>> void *kaddr; >>> int i; >>> >>> - if (khugepaged_max_ptes_none == HPAGE_PMD_NR - 1) >>> - return false; >>> - >> I do agree with your usecase, but I am really worried about the amount of >> work and cpu time the THP shrinker will consume when max_ptes_none is 511 >> (I dont have any numbers to back up my worry :)), and its less likely that >> we will have these completely zeroed out THPs (again no numbers to back up >> this statement). We have the huge_zero_folio as well which is installed on read. > FWIW, I am still hesitant on this patch because I think the whole deferred split lists + interaction with the shrinker should be cleaned up along this patch. > How about just doing a memcmp() between huge_zero_folio and folio? We know > exactly how this folio looks like, in case of max_ptes_none == 511, if it > is to be eligible for shrinking. I wouldn't really want to optimize for this case, especially given that (a) I want to remove all direct dependencies on max_ptes_none and any special values. (b) The huge zero folio is not always around (c) The kmap local prevents us from doing that (in particular on 32bit). -- Cheers David / dhildenb