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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Rik van Riel , Harry Yoo , Johannes Weiner , Shakeel Butt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kiryl Shutsemau , Baolin Wang References: <20250918112157.410172-1-kirill@shutemov.name> <20250918112157.410172-2-kirill@shutemov.name> 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: <20250918112157.410172-2-kirill@shutemov.name> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: qcE3tDNTr6pxO97uBW4sn6sA6XDBCRj09UFah-7hRk4_1758195035 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 069591C001A X-Rspamd-Server: rspam05 X-Stat-Signature: zgk5eud7srsbqnqyc35dcsya3zcamow1 X-Rspam-User: X-HE-Tag: 1758195043-852949 X-HE-Meta: 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 sd7bCi6o Hg9DPSVFmjW2pzY5q7bbGigQ/Hom1oMsMk/uChCiD75p6t7ykhS1H62b6QeNaj8seSBgc0hz4nw01ECDcpQ3KBSIRmhvZeC1+Rie/dsk4FmoQucdXHrhw/Mjw5mBMX81AY2JFU9oR9Fu9TXazQXDFNsZNOJJSIbFFO+dHTKYLOii/P0vKcGR4OgnNYgMrISc2uNGSol8UIXck1+r2G0rgAhmfajCFapWmXuq2/VjXn6fPpsA4OOt8EIt9QC0B8wM3IM/VM1dBA2ViJlSpfupnfC089VV/UG9Uejt0mjR68ghFka33iA+b8uNdH7kNCew+BviIEidzeFiS6ZhmKfLQa2cuqOTTFjt6b6f7k5O5KxC1+Ou4rxQVCYrVsuxqB5iIs2ufEvY4+nkK4TgfRL8RAbceTdhaQxU1RjVXQcz44uuBmIvuITeyhVh0YqV9y4hCyeqjdX4qkDi2gPxYTQr/AQ+849nqhrreOJDzavW62CyV8MlX4UzUOHymIEh2HbcEo5P/drISAzvG7I0= 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 18.09.25 13:21, kirill@shutemov.name wrote: > From: Kiryl Shutsemau > > The finish_fault() function uses per-page fault for file folios. This > only occurs for file folios smaller than PMD_SIZE. > > The comment suggests that this approach prevents RSS inflation. > However, it only prevents RSS accounting. The folio is still mapped to > the process, and the fact that it is mapped by a single PTE does not > affect memory pressure. Additionally, the kernel's ability to map > large folios as PMD if they are large enough does not support this > argument. > > When possible, map large folios in one shot. This reduces the number of > minor page faults and allows for TLB coalescing. > > Mapping large folios at once will allow the rmap code to mlock it on > add, as it will recognize that it is fully mapped and mlocking is safe. > > Signed-off-by: Kiryl Shutsemau > --- > mm/memory.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 0ba4f6b71847..812a7d9f6531 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -5386,13 +5386,8 @@ vm_fault_t finish_fault(struct vm_fault *vmf) > > nr_pages = folio_nr_pages(folio); > > - /* > - * Using per-page fault to maintain the uffd semantics, and same > - * approach also applies to non shmem/tmpfs faults to avoid > - * inflating the RSS of the process. > - */ > - if (!vma_is_shmem(vma) || unlikely(userfaultfd_armed(vma)) || > - unlikely(needs_fallback)) { > + /* Using per-page fault to maintain the uffd semantics */ > + if (unlikely(userfaultfd_armed(vma)) || unlikely(needs_fallback)) { > nr_pages = 1; > } else if (nr_pages > 1) { > pgoff_t idx = folio_page_idx(folio, page); I could have sworn that we recently discussed that. Ah yes, there it is https://lkml.kernel.org/r/a1c9ba0f-544d-4204-ad3b-60fe1be2ab32@linux.alibaba.com CCing Baolin as he wanted to look into this. -- Cheers David / dhildenb