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b=NQywSJLG93kGO78eU3Q3Xg4JxVUYRuI5M/N0LJ0toaNH6jIQUP/jy5ijJSDoDtmp9 JcVpY79wvK41PQmbzVBd7/zKGFJp1PYfu10ch67DsDDWPO3quOYlm7QlQRih5HtyLC 5N5nqQz9Of05WxCvsIEFXnD6ixHhTRpsQwyf/6ntwryLcJ6Tzo7+BsynRMsu8aVqRP 42SSPM2FYQxM1obALTH1EYEg0ivd0FanZEqx9APLSa6jUIAji80WfVQl0m79y3l+MH JwLg8KmfotgNA18XAJv6kRf38P6kq5K5xPByjvwpg4iPslmDZPv6MbtC6cANi/4UZX qrG7rA2rjWFGA== Message-ID: Date: Tue, 20 Oct 2026 15:07:24 +0200 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm/compaction: skip folios containing hwpoisoned pages To: Kaitao Cheng , "Huang, Ying" , Yuanhe Shu Cc: akpm@linux-foundation.org, vbabka@kernel.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, ziy@nvidia.com, wangkefeng.wang@huawei.com, tujinjiang@huawei.com, mgorman@techsingularity.net, chengkaitao@kylinos.cn, muchun.song@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260928105805.1215770-1-xiangzao@linux.alibaba.com> <20260928105805.1215770-2-xiangzao@linux.alibaba.com> <99cbd960-439d-4672-aba9-6b49697db8b3@kernel.org> <20260929034123.2705745-1-xiangzao@linux.alibaba.com> <877bjowf9i.fsf@DESKTOP-5N7EMDA> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 06D9FA0007 X-Stat-Signature: 77ewfme67t6okg3n4suq5pmsmy7uprtd X-Rspam-User: X-Spam-Status: No, score=-7.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1792501649-644425 X-HE-Meta: U2FsdGVkX1+ApNJTznSywk/rQOtPWyrJE3wrYeWcFWCO6Rh+1QmWiKNlQSRGldr8DScCs3IeHEbsgeuuIUJer/pqbLNwxiUmTRZlzzMXRy6Ekk9FrOfPH3UKCBVsFPjyNR6lxP+9gw9GRwOFi6JrxOsH1AdQQ0bJtWHYebktqFR+VQvXCojs8c8AA9cJP7DWaQt5VMbir0+eM7tIB4FGeP95obxPkTKVtokl9sjYgC4kb8F44nzxOPliOPnkoIjmOYtHm8So7Am/6Lnn8DiOMJbCvx6kKaM/Z3iM8iSfUVHT9dPRRHy2z303Ls4aWR3cnp+QRF52tXfFxKwM3bZBlu3zvrjBD9SrqD3OSUEt+FrW5e2CwQ3GrJMNI2tsN4IczERcIwGqJmEsfxlT1UKzrYuCsTUSUd2YwIvUJ0pQwqEu3YhNReSuXGWj8TFwcTESvAwYAvPlGF3yqbp+eP+0Vl+SAR2V8rxC4vkUWvtIgH8k/I+kI5GnG5M78mymWJHRgSwbJzdbAp7NVM9EgsJFgmW38nzRdFTZ4OL6csqLzIv/X/izsxrYgIGFJMWPJscP17bk5PiJeitrjZQ05Bz+k43pmRhrNAEzX2GVffChSJ6NLKn0OAZY8cSw2BDk6kvubiisa+Cvo+G4D/1tejXvli8xJ7lJgK9Zz7DEhdUTqUJUog1MllYjpc4id9VWgyxASv72St1iaEdLlYaMh/1wM9ahwqF/6fJOrdRX6JpigJPL856ko0s/JMxscSEgVS6mhb17mytbCfstso68lo4pCtazIRq50lU3neWb+PXEAONyBeVkj/pge5nNW/UcDSB6l72eZTt1wBIsyL3c/tvNP14pRI6QmxeIV4amOWap8L1z40lYY2J9oYuE8OOBKm6KDJhOuBK6Q8N+oTKqIfBDn/Aas16TptSPHFl3Um+NKb9vNFdDcBPZUJP01o1JHWho9LZ6HmVlvgRPmdyd4ti QkJjikI6 Olls1Mq1j7cxIn/68SXLKZaC20u29CUXEpOc/S5DDc188Cfy4kdTFL2MQZUnsMQa80sk66QrDWcpM/29lCc6AL6I2q4hnEQ5hGjjF2Q4LrE1CC6GLM8YjktnGeaHe7TNlVkpaC/3kpeIqcaekNShwIIJcORI0HlDlAXk7FHDl1Es5AmvYdAHOqLE3ol7czmivBjOTvdfDd8CVqKGuTgmMOIcKvu/N843FIB2asK5L7r1meqA67msU97UQlH/UbWtR/lok/AcObVc+2Wq8rW9/VlsB76HiL2agCkFZ+VZqmCUa0vZKGa5RTR2KkGVv2Li7KQucPgVQ4QThVWNsl8HefH/H0nTkdEhO1AqqOiPI1Z8bbQr0cCyri83kMuPK702xByek Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/20/26 13:27, Kaitao Cheng wrote: > > > 在 2026/10/11 21:14, Huang, Ying 写道: >> Yuanhe Shu writes: >> >>> >>> Agreed, and nothing here replaces copy_mc. Two things the check adds >>> while that work is pending: on archs without copy_mc the plain copy >>> does not fail, it consumes the poison - the same poison consumption >>> commit 841a8bfcbad9 ("mm: prevent poison consumption when splitting >>> THP") refused to risk on the split path, at your suggestion; and the >>> refusal happens before the copy is attempted at all, while copy_mc >>> recovers only during the read. The check and copy_mc compose. >>> >> >> Is it good to implement the trick in copy_mc_user_highpage() and >> copy_mc_highpage() if the macro copy_mc_to_kernel is undefined? > > On architectures with hardware error correction and exception recovery > support, accessing faulty memory automatically triggers an exception, > which itself guarantees atomicity. > > On architectures without such support, even if we implement this logic > in copy_mc_user_highpage() and copy_mc_highpage(), checking the hwpoison > flag and copying the data remain two separate operations. They cannot > be performed atomically, so there is still a race window between them, > however small. Yes. And you need proper architecture support to fix it? > > Moving the hwpoison check after the copy might address this issue. > Is there anything wrong with my understanding? Will architectures that are not prepared for copy_mc_user_highpage() not simply crash if they trigger an MCE during an access? -- Cheers, David