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[2003:d8:2f09:9c00:8173:2a94:640d:dd31]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45c6faad9cfsm33627155e9.0.2025.09.03.01.25.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Sep 2025 01:25:16 -0700 (PDT) Message-ID: <28e704b5-92ae-43a8-80a7-3746db1832fd@redhat.com> Date: Wed, 3 Sep 2025 10:25:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 5/9] mm/shmem, swap: remove redundant error handling for replacing folio To: Kairui Song , linux-mm@kvack.org Cc: Andrew Morton , Matthew Wilcox , Hugh Dickins , Chris Li , Barry Song , Baoquan He , Nhat Pham , Kemeng Shi , Baolin Wang , Ying Huang , Johannes Weiner , Yosry Ahmed , Lorenzo Stoakes , Zi Yan , linux-kernel@vger.kernel.org References: <20250822192023.13477-1-ryncsn@gmail.com> <20250822192023.13477-6-ryncsn@gmail.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: <20250822192023.13477-6-ryncsn@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: IhuYkrg3hBtMD1xLWLQrolJ7Hy9vJ17YKgZVYEiu520_1756887917 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: 8DAD0C0007 X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: 1sh38bqzogqg5mgyubro5fikduu5x4hz X-HE-Tag: 1756887920-615946 X-HE-Meta: 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 OCyNhKxM EtVOceTvlDiXbTPlYdS0mkUG8aDzeCskwcXTfOpXBTrXIaNyRhIWFxlx4+VhKmSgiVvFzjIzmqtidObquKmGAqqNmoJlyRQb6O46E4H+UYt5BRYadopjhpx8JRY+/zm8HXbbLubTAyZ2AlLq+7ou2wpnrhSvkTBG9uTwUeqbxSiPNKj5nCScTCIlalN2//fPiwj6433GD20HMZ4rRetBcoEyrSI7v9iRzjRH1EMWq2mtRKdfSEHLSty2+6SPcvD9y2ORpUUHdRNY0nDGSF6FJTM34AJP6dkQGakA44OwYu74p1MbJDDqylSizoQlaCAQt0yreQkjCH8fIhYWKZ8DJAgKZ6hPCK5zqpsFQuijvC7BoUEQWthnLo+d5Po/fIN4khiWEtRqHQKVHddKjDc+fnKqyL8wYnb2tJVmjBu9kRvyh41Qc4BtbuwQu4jS6XLp0KMxIyYfwLq77Agdd3gQyGKxjcQ== 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 22.08.25 21:20, Kairui Song wrote: > From: Kairui Song > > Shmem may replace a folio in the swap cache if the cached one doesn't > fit the swapin's GFP zone. When doing so, shmem has already double > checked that the swap cache folio is locked, still has the swap cache > flag set, and contains the wanted swap entry. So it is impossible to > fail due to an Xarray mismatch. There is even a comment for that. > > Delete the defensive error handling path, and add a WARN_ON instead: > if that happened, something has broken the basic principle of how the > swap cache works, we should catch and fix that. > > Signed-off-by: Kairui Song > --- Sounds sensible to me. With the "!error" code not deleted Reviewed-by: David Hildenbrand -- Cheers David / dhildenb