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[80.187.83.189]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46fb489accbsm219125495e9.14.2025.10.13.08.53.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Oct 2025 08:53:47 -0700 (PDT) Message-ID: <93d00bb0-8aa7-4f52-b9ba-ef777ec191dc@redhat.com> Date: Mon, 13 Oct 2025 17:53:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] mm: mprotect: avoid unnecessary struct page accessing if pte_protnone() To: Kefeng Wang , Andrew Morton , Lorenzo Stoakes , linux-mm@kvack.org Cc: Zi Yan , Baolin Wang , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Liam.Howlett@oracle.com References: <20251013121536.2373249-1-wangkefeng.wang@huawei.com> <20251013121536.2373249-3-wangkefeng.wang@huawei.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: <20251013121536.2373249-3-wangkefeng.wang@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: cPIvV3JbeTRZxVkkJqI9s7T1crYjrOAEwALq9Seh0BE_1760370829 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: 59mwze48q4dbjnroi9d8ooxx4d9pfdqq X-Rspamd-Queue-Id: 89B6B1A0013 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1760370833-254006 X-HE-Meta: U2FsdGVkX19umFt8l6egmd+loemIV2xUK/t02LYkmsgmeLdMg9Ibq2fyoF+5Qctez/4vQQXHyROALnxJ5xsdOfRgzrSbGmAH7xeAixdHI9AhTvNNrFXIAYCDukz6lEtA9AT+faLzICewB8/I+50X5h86lOfXFK09TLvr1skftrFvalghNuRbOwgMubiSsvr1EQNFftkRjpm3hXQ+OY5xvO/2TMWi/insRPrjPnZQ3aPez3Fz87Nj+kx/UjpwN72OfIXHSuuC7mn9cfcSuJRAWu2BqVMYAKjMTrHCyz0Ns0/lg4n/cM4iKNb9b/kcwGXj8b/BtVb/vFw6CJbM0hLvX1xHl/HR41AN1Ik7jYgBqxIL9JgCaQV0MsxphY7TXfQBTKovt30ZFfQT4pIITyel7K9e6dVBjobizl6/pxjyBYOuHnbGHFdXF9pxjaFEPb8zGaQWJe2FT7z5IbEGTF30NUrEqcHN6zUKTaxrvCXhBZjNkZVocVjav3fD08SyHpaWK699b5m8tNp5Wz3yCbMEaOTfajJtd2a5p26wMAvopLamhbzswox69kCqm5z3/adXYeRC+vmLr4oSpnRWO9hOB7Hpcf5TsxICNQbx8IOe0c1wvGQ2gCMIyaROD69MmdPWuu6L2X7P0LJ7/v125/xmq/2hoKeuIVUuubrIS5uxRREyIB3PGmgVefVnAjKBXHl41bR87ugJYc7/gXSYcKywHhAUfyhHYKOtPnbl09L/TvcWuPtfbjJMZODzssUPotjUyFOG9tqHWg9tS3yPYQy9e1t/7E3i/Zy8U0Dyrg8s5Ln6WZ9NO9gMj+67u3RU+hd/LcaLo8nHFjmRZA4XRUERVHj6HaAqCRwBjsBZSds1SwP6oO5rhg7yrM9q2IK8N762aickMV1SXO9xuC7qNCCCmKGSQCtsayVR3enGNi9tibRyk49CoZmxKInmQmSgj9RBrEyykzdaikVXkoRjkvE 57ImURVS 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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 13.10.25 14:15, Kefeng Wang wrote: > If the pte_protnone() is true, we could avoid unnecessary struct page > accessing and reduce cache footprint when scanning page tables for prot > numa, the performance test of pmbench memory accessing benchmark > should be benifit, see more commit a818f5363a0e ("autonuma: reduce cache > footprint when scanning page tables"). > > Signed-off-by: Kefeng Wang > --- > mm/mprotect.c | 21 +++++++++++---------- > 1 file changed, 11 insertions(+), 10 deletions(-) > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index 51a28781de9d..0f31c09c1726 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -118,18 +118,13 @@ static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep, > return folio_pte_batch_flags(folio, NULL, ptep, &pte, max_nr_ptes, flags); > } > > -static bool prot_numa_skip(struct vm_area_struct *vma, unsigned long addr, > - pte_t oldpte, pte_t *pte, int target_node, > - struct folio *folio) > +static bool prot_numa_skip(struct vm_area_struct *vma, int target_node, > + struct folio *folio) > { > bool ret = true; > bool toptier; > int nid; > > - /* Avoid TLB flush if possible */ > - if (pte_protnone(oldpte)) > - goto skip; > - > if (!folio) > goto skip; > > @@ -307,17 +302,23 @@ static long change_pte_range(struct mmu_gather *tlb, > struct page *page; > pte_t ptent; > > + /* > + * Avoid TLB flush if possible and unnecessary struct > + * page accessing when prot numa. > + */ I think we should just simplify to "/* Already in the desired state. */" or sth. like that. No need to mention the struct-page implementation details in this comment. Also, I don't think there is a need to mention the TLB flush when it's really in the desired state already. > + if (prot_numa && pte_protnone(oldpte)) > + continue; > + > page = vm_normal_page(vma, addr, oldpte); > if (page) > folio = page_folio(page); I could have sworn we discussed that while fixing the prot_numa_skip() fallout. -- Cheers David / dhildenb