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(p200300d82f4e3200c99da38b3f3ad4b3.dip0.t-ipconnect.de. [2003:d8:2f4e:3200:c99d:a38b:3f3a:d4b3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47496c2c9dasm13207305e9.4.2025.10.21.02.47.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 Oct 2025 02:47:13 -0700 (PDT) Message-ID: <37ceab54-c4b2-449e-aa46-ffaefe525737@redhat.com> Date: Tue, 21 Oct 2025 11:47:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] mm/truncate: Unmap large folio on split failure From: David Hildenbrand 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" , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Kiryl Shutsemau References: <20251021063509.1101728-1-kirill@shutemov.name> <20251021063509.1101728-2-kirill@shutemov.name> 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: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: sWHDZNlOSyedfw1UUFbtBdI66u9nTPJn3nuB-W_no64_1761040034 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: rspam10 X-Rspamd-Queue-Id: 8BB1F14000B X-Stat-Signature: nd19am7rbj3ka61dfqzo36mxqgknk78y X-Rspam-User: X-HE-Tag: 1761040037-181006 X-HE-Meta: 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 QmxbierJ uT6FG1nO3naqT/hJyPkmAKoSb7Uz33iuYjlECjANMyLDtEPXnuonhrQVTSCvvKmGm815LCW70Yattv9DOA0ocbaEwTtPCtwBmw8e8YQvxBoJjhWA5Saxz7dKE9ubwDju/ens+CpMnuKfxmeyIy/ztRn4quk/aO0LaO+O/6rO/rYin2MMdD6Yubulh8fq5CTqolD48bqxexmDs+EedpAf2B4wJgdui5na61yLXGAE7nsJxRupISf5QPB2J/y1Ia9lzz1wneNs+dao+MVySUTokPmGw4LuCn5sC5JtaJ/uqIg2oiKIbueRtZr0ORvGh7ZODqhzhVn1OcCnkieF4SudG6t5IunTX7jPsuAT4Arz+e3BrnCJYLmzypji8KtzzfXEzMOP/F/UQC23CSNb0WCvqj/HP8ySAnQv2+Kyxe4CUbtnu2XQMbTi1p7PB6cIGQuc4vsaC/ZfLTqU9SKU= 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 21.10.25 11:44, David Hildenbrand wrote: > On 21.10.25 08:35, 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. > > Was the discussion on the old patch set already done? I can spot that > you send this series 20min after asking Christoph ^ Dave Also, please send a proper patch series including cover letter that describes the changes since the last RFC. -- Cheers David / dhildenb