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[2003:d8:2f20:da00:b70a:d502:3b51:1f2d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3e7607cd4cdsm6980192f8f.37.2025.09.12.09.01.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Sep 2025 09:01:43 -0700 (PDT) Message-ID: Date: Fri, 12 Sep 2025 18:01:40 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 04/15] mm, swap: check page poison flag after locking it 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, Kairui Song References: <20250910160833.3464-1-ryncsn@gmail.com> <20250910160833.3464-5-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: <20250910160833.3464-5-ryncsn@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 98TaymC5nm0egZhm5xVIc0GqTlxW3VNYFERenA-bTfM_1757692904 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: B9EABA0011 X-Stat-Signature: wfa77mninwx6yt3343swnnz3jbt41r3e X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1757692907-566273 X-HE-Meta: U2FsdGVkX18oTV7iJDSk1CYgHgnKvhNlxVqNhPuykPukyDCYd400rUNLDVVOT9FMyMrvCzBXx87zBb7Na/ibiP9uUCBptS/9coxNNnBnyqpcUTAm4cSAi2bHfY6+ZnRQJDmIRqqyVXw8cm4b6PqZm4ioa0XudgVFuWvpSEgJo/ASuGdOLrZIZ3wReDrK1XP/Gbh3hq9oZyqkxVpuhaITrHE7I8b1Kl9VLqDxcmAYbhFrNpwWyy2gigjdkk8/yG0iUxa6eZsETNyTXivTufnXhMrFf+/y6DNfryNjb/kGyTRk7X/8RgpKQI97Q4L2tfKAj6htQSSMSurHMJM+k5TY6MSDgF5ngurroWOcUI+8t3irAd5/XeQDv5PVVQq6zFbEB38qdwN+TGA3oN9dexjQTBhySBO1y4shSV3Z487oZJGuCAPJhIbaZHMhtNkSk2Uybixg91OW4j5TJgAgF8uCj2AGQvPhmAIUoAsZgCbBm6wd46MtSD8iaueDVteDQVWv6TFP/nAW6ZfeqGAPgjLewllB0RUpRXBS/UcjuPKP8lW4JXwk6SHJp9byj4HsXzMmafY4Q9Y6fKAr8UFcF+hOBj920J5KHFxREj7irjKLZ3zM2B9M+UjInif3vvsrEm1x8XjRtPSUM12iXyyaiGOWJqUKmeVAF3n/9apuujbNpyUjeEEalwvaeXO64fEE/v3ZTGV1OfEQF3vTJvIiBLFSShpN0Np6fy0sdsDiouKXHOXwBJiksexT6Wot1gQ0cyHLGSxMMHkCBIqKAh0h8sA9tAxgSZBFA2qpQBZIqZEobGk6n1tWuEAutwLuiTyOUfQnQHz/rRyob/WhXYV0xl/bDNadstqLDJbg7URTlETmldHdGZCsfQP4UkK9BRYCuCGqbtNYxlcxYaqe3nZRwsR64S4xVnd0Pi6TCPT/ltN9JzpIj0eRNWENTStpJdMDV/ir30KlrSX4MfSHn/tgLZr FYvl8rYr S5KASkwzMK7pxVVaKqgbRya9xillkFiTBOxI1l1fpoWF97SYv+nb+oMh4YCki93oYxw6pV02PS3UfX93CePAjGG00ixWSyvSRBsUBOpFVbipNoyfsrjAazsWJ+TDWIQJsqNw4rJM8ugMAz5Ki5Hxs91PN5m4yryGxaphJx+xK5aXuuXXj56Y3F5oiTGp5kFlcXza6nOICW7QSVmPgsovjh29gn4Ww8fOqpLA1IBh8mhWQB1Dpj0Q+vX1GOA5gRe/RQJdMKpH1Pq8HjcYS4b2eYwCW7vNbv2h1XZlBp8G0pJO2peJ+AKRXJfFqmmvEq0N2EpIgNrOSJhOmM49/OgG7mjBIRKsHkzzIjIlmNkClwxsTLscHpjTGjkkGnUilOIFS19MhQjYrbgQqVAerVYeij3WjfAbrOvfLVwpzogum4B1vbJpGOvl3Twf8D+lwIEousVhT1rU7TNyfYdlkN+fCyFMVgA== 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 10.09.25 18:08, Kairui Song wrote: > From: Kairui Song > > Instead of checking the poison flag only in the fast swap cache lookup > path, always check the poison flags after locking a swap cache folio. > > There are two reasons to do so. > > The folio is unstable and could be removed from the swap cache anytime, > so it's totally possible that the folio is no longer the backing folio > of a swap entry, and could be an irrelevant poisoned folio. We might > mistakenly kill a faulting process. > > And it's totally possible or even common for the slow swap in path > (swapin_readahead) to bring in a cached folio. The cache folio could be > poisoned, too. Only checking the poison flag in the fast path will miss > such folios. > > The race window is tiny, so it's very unlikely to happen, though. > While at it, also add a unlikely prefix. > > Signed-off-by: Kairui Song > Acked-by: Chris Li > --- Acked-by: David Hildenbrand -- Cheers David / dhildenb