From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C1A9F606A31A for ; Mon, 26 Oct 2026 09:57:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ADibYKa6 Received: by kanga.kvack.org (Postfix) id D241B6B05C9; Mon, 26 Oct 2026 05:57:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CFC126B05CA; Mon, 26 Oct 2026 05:57:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C11DF6B05CB; Mon, 26 Oct 2026 05:57:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 8EE776B05C9 for ; Mon, 26 Oct 2026 05:57:05 -0400 (EDT) Received: from smtpin11.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 0C1671606ED for ; Mon, 26 Oct 2026 09:57:05 +0000 (UTC) X-FDA: 85364324010.11.14B3696 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf28.hostedemail.com (Postfix) with ESMTP id 4F25EC000C for ; Mon, 26 Oct 2026 09:57:03 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=ADibYKa6; spf=pass (imf28.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793008623; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=uEc1Bmciiva82nUX+FVCSYZVGtSGCp8Z+LUTT/EsGek=; b=LLjbS/6E1hvO1jZlVXJr6uB5GYfSqugskZl3BmpGrgiRKTPPm2Tgq4OYulnJL+dka8DT9T BYE2sF+Z/txBEtRBdrQeAcT+b3FZi5+GNoo2lL7o+SSA/T3p8XcNYPOEv9SC1vM0U5LKHL Hj+LT/ki/8xUzy4i34xCeWi/Z67v3Y8= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793008623; b=yPhwJIslOCHCVOWDRRu4UK2zNmE8DkUmlm/BfFed/EKUszaXDb7y+55IG0VupghevnfUcL GoLuM7FOK+CnUfPHTvAhr71UhFSybPOdk+PV0OuTwxZzVNzu1/Qn/Jxxdb+PYhOJ40ufWh z4b65rO7uUsC9AaGCa+a8bGOf3DgFWA= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=ADibYKa6; spf=pass (imf28.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id D819D601FB; Mon, 26 Oct 2026 09:57:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFB981F01825; Mon, 26 Oct 2026 09:56:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793008622; bh=uEc1Bmciiva82nUX+FVCSYZVGtSGCp8Z+LUTT/EsGek=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ADibYKa6IDFelyxOrz8R24pUpYscXPB+pjFUqfN2yzvXXexfAjjlvE8xEfbuxib1a 9iuKKqlbVMsfHNfY8DCH1nNOgHe4kTajBG8upwqlZp9HUaz0Jm3ecdaV86Vb7/vNvQ pVTUkIJ1PrXGqNfuWJj4ilB87T5xg70/iei3rAqXx6qEUbMNQlQKTCvPCNx0BPsKu1 lpfZjxcbWshFPOnI+aAlGyoG1VN7lODhcoXGWlZH27/b+4YYdt8nqCAscjnoWTkJKj LVXMT/ryh3eVhd+NCWnLLVqiT4ue426VHLCP7J6ORkJwIvkzwPbZ4RahyvrSR2DIY2 D2GTiBGBSgRPg== Message-ID: <18602383-2326-4e54-8dec-bb695ae8878e@kernel.org> Date: Mon, 26 Oct 2026 10:56:55 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/2] mm: don't migrate folios containing hwpoisoned pages To: Yuanhe Shu , akpm@linux-foundation.org Cc: "Huang, Ying" , Kaitao Cheng , 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: <20261026025552.1427901-1-xiangzao@linux.alibaba.com> 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: <20261026025552.1427901-1-xiangzao@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 4F25EC000C X-Stat-Signature: secsjm71e5nba1ybijcenw1n63a36ngj 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: 1793008623-776427 X-HE-Meta: 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 1dci+Vi0 F02I2iWrFD9V/KMMw0xLKASzDHp8t8gpjI31RDvMypRLoOVkl00k3uiLaYVITjWZWtbI7SOBChejOTg0H3oFJn2L/1MnRcXKRo9Bxv3hUtwHmOXEVmSPs2D37EpNwAKgH/P0+yAjEbmsLs9lUt/XiuyqTV3uF+xjaH8gHEiZhircV5Lg/ieWM5rDDwCdLbaLFWObMDlmnpSWtjY3P2JUSmNZ2aSCjCaBECs29x9MwoXEM0lUNYi68gMBG9tw7WLx/z3yaUqnt3LXNFPcpi2wADyaba2XDX7fpb7zOv/NZd9f7ynOXTgkfXWmUYQykk5g9O+YeoNkOMZUYKjI= 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 10/26/26 03:55, Yuanhe Shu wrote: > v2 of this series. No changes to the approach; the two deltas are a > wording correction promised in the v1 discussion and a third check > suggested by Kaitao Cheng. > > memory_failure() can end up abandoning a folio while PG_hwpoison is > already set on it. Two ways to get there: > > 1. Race: any isolator (compaction, NUMA balancing, move_pages(), > mbind(), CMA, long-term GUP) clears PG_lru from under > memory_failure(), which then fails the HWPoisonHandlable() > check, exhausts the get_any_page() retries and bails out with > MF_IGNORED - without holding any reference, but with the flag > set. > > 2. No race at all: the THP-split-failure path > (kill_procs_now() + MF_MSG_UNSPLIT_THP) leaves a large folio > on the LRU with a PG_hwpoisoned subpage by design. > > In both cases the migrator still holds the folio on its migration > list and migrates it like any other: the corrupted data is copied > into a fresh folio with no poison marker, and no hwpoison PTE entry > is installed on the way back, so the userspace mapping is silently > redirected to the corrupted copy - no SIGBUS is ever delivered. > > This was reproduced on v7.3-rc4-75-g62f4c998b297 (the base of > this series): an order-0 stress workload (madvise(MADV_HWPOISON) > racing move_pages()) left the poison flag set on 8426 abandoned > folios in a 180-second run; 698 of them were subsequently > migrated, and in every case the address then served the copied > corrupted data with no SIGBUS. With patch 2, 0 of 9711 were > propagated. > > The compaction-side guard is needed regardless of how the race in > memory_failure() itself might be addressed: the steady state > (split failure leaves the folio on the LRU with the flag already > set) is not a race at all. Deterministically validated 16/16 > poisoned mTHP folios migrated unpatched vs 0/16 with patch 1, > with clean controls migrating 16/16 in both runs. > > The checks compose with, not replace, copy_mc: folio_mc_copy() > still catches real-DRAM corruption during the copy on archs that > implement it, and the flag checks refuse software-injected poison > on all archs before and after the copy. Extending the > !ARCH_HAS_COPY_MC fallbacks of copy_mc_user_highpage() and > copy_mc_highpage() with the same flag check - which would also > cover their non-migration callers - was proposed by Huang, Ying > and welcomed by David in the v1 discussion; that is posted as a > separate patch right after this series. With that patch in place, why do we still need these changes here? -- Cheers, David