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(p200300d82f4e3200c99da38b3f3ad4b3.dip0.t-ipconnect.de. [2003:d8:2f4e:3200:c99d:a38b:3f3a:d4b3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-475c4342946sm156957715e9.10.2025.10.24.08.43.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Oct 2025 08:43:38 -0700 (PDT) Message-ID: Date: Fri, 24 Oct 2025 17:43:36 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv2 2/2] mm/truncate: Unmap large folio on split failure To: Kiryl Shutsemau , Andrew Morton , Hugh Dickins , Matthew Wilcox , Alexander Viro , Christian Brauner Cc: Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Rik van Riel , Harry Yoo , Johannes Weiner , Shakeel Butt , Baolin Wang , "Darrick J. Wong" , Dave Chinner , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Kiryl Shutsemau References: <20251023093251.54146-1-kirill@shutemov.name> <20251023093251.54146-3-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: <20251023093251.54146-3-kirill@shutemov.name> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: IMl1I4mrBWHN_6MTo9apmyEBRYdUV5PDAiUmB3gSeQ0_1761320619 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: fzfcmjzud3pijxtuqa88zeezo9s3y99o X-Rspamd-Queue-Id: 6A8E3C0011 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1761320622-136131 X-HE-Meta: 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 eNPWhiOT 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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 23.10.25 11:32, Kiryl Shutsemau wrote: > From: Kiryl Shutsemau > > Accesses within VMA, but beyond i_size rounded up to PAGE_SIZE are > supposed to generate SIGBUS. > > This behavior might not be respected on truncation. > > During truncation, the kernel splits a large folio in order to reclaim > memory. As a side effect, it unmaps the folio and destroys PMD mappings > of the folio. The folio will be refaulted as PTEs and SIGBUS semantics > are preserved. > > However, if the split fails, PMD mappings are preserved and the user > will not receive SIGBUS on any accesses within the PMD. > > Unmap the folio on split failure. It will lead to refault as PTEs and > preserve SIGBUS semantics. > > Signed-off-by: Kiryl Shutsemau > --- Thanks! Acked-by: David Hildenbrand -- Cheers David / dhildenb