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b=X6bW6IZ7dFcKRgkT/2wU1TgO3ksnK3HpyVnM+mmOXcYwtJu6Jz+4NhKYoPSRiVqCW HIj+aky7TYvJJYoMpMcc6X4RVH2zototSzP5XjTqp8gkSQDQfP6Y7XvRDcfiPFXqQn jph461cm0SwaF0FvLf/ndNwDEXxreM+rO8d0P0EO8VWFN9gYaYzLFuimJiSyM+pzKu wKEvqLI/peX3H6x2RLAJOZj/vwmbdi6VlByxZKHChlMD9dYp8utVoXeKXL1pUyQiHM iYe57d1imqAss5kvOXDP935Y05SAhmftxl0i2QgHoAIYaPkPYjRczu8gMsDpsnixt1 AdO4iyaPao2FQ== Message-ID: Date: Tue, 7 Jul 2026 12:08:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/migrate: Avoid copying hwpoisoned folios during migration To: Kaitao Cheng , Andrew Morton , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple Cc: Naoya Horiguchi , Andi Kleen , Muchun Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kaitao Cheng References: <20260707090136.52904-1-kaitao.cheng@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+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: <20260707090136.52904-1-kaitao.cheng@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 28AC61C0003 X-Stat-Signature: b1bc888zucocwkg7chr8pnbsufq8nknm X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1783418912-163587 X-HE-Meta: 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 dla3nA3i 3kvR0iLCtqm71Rv7a+m4zXCM8cuefgHOwITLkYZbSxHriyPQWHD1XVVdn7EZZ/gObhvgr9sAcC0LKIlAj8XySGtRrKkdIvknzO5TGXu3snL6goznhdXKPG3Oo/PaPndgDUBXJaXV62AsEn0p2J6A5NzaXYpfTXV3axqNPi64Poqjj9MRDI7qeRVnvetD4Eyg1G70hM56D/ay9rl+07CpnjXNi13ns7ezyf9ulHl02yLjdJmqe/vsPChZjJgtbR/IinMknkSSAETIJbdsTz9aRzynh7PLeMCfm5ZqI08E42AbfATHBCCbkqeWa5wEyP6Jh7awQ/ZgYtPf4GPg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/7/26 11:01, Kaitao Cheng wrote: > From: Kaitao Cheng > > The generic folio migration path can copy the source folio after it has > been unmapped. For normal and THP folios this goes through > move_to_new_folio(), then the filesystem or anonymous migration callback, > and commonly reaches folio_mc_copy(). > > folio_mc_copy() uses copy_mc_highpage(), but architectures without > copy_mc_to_kernel support fall back to copy_highpage(). If the source > folio already contains a hwpoisoned page, a normal copy can consume the > poisoned memory and trigger a synchronous machine check. Well, but the code can still race with memory_failure() IIUC, so it's not really safe either? -- Cheers, David