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b=PM53I5cc33ohdAjMTn0Uf70/koVDQJId9SXhNgrzvyHoQ5uH+/rGSI/nTuEG5RoNz udGMlFW3HYIlwcK2oNmsvavkXhxbnjFC14MirI+Veow+/hPQ4myfQPbLxwVI/zBOqx 9iqTuqLrYwWlxGbsB5uRE1Uxfi7UV/+uOZ1EoYkwquIiZvv3HK5mujkfojeCsuF//7 mFmD7b1tk6hbEIUt8HSU0Llv0RHdvDXgN+4lvXrFsSBinD87FnMRdxApxuiOH91akE UsfN12Z3nKK4+gCOoYjdMBIC8/3kTmH7KOdEzmTZrAgcXSplXrKCz+XzDpp6uvsP/+ lkRxHk+ZribPQ== Message-ID: Date: Wed, 21 Oct 2026 10:27:55 +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> <23d3756c-1a87-402d-80b4-c838dfc29f4d@linux.dev> <9da90d76-031f-4211-b9de-439cbf7bc63d@kernel.org> <49966df8-c092-40de-a05a-ff6d69382dd4@linux.dev> 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: rspam02 X-Rspamd-Queue-Id: 2AF66140003 X-Stat-Signature: uofpjhe341rzukn51z7wux4c4s51feij 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: 1792571281-980750 X-HE-Meta: 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 66r3bPyC g8n0IfAPIoQkXV2k16m5Lf8f6Uhq5dunBK5Pq5eFfPbFpZ7bYzM/lxKhmy5InT/gyNPNVW/4H6KAAP03dHvXXfpEz4TH+Ll44ypJCe+1k5+1b0IY04HEjt9WMZSRqg+RbUL+nElItGYywwgGs1SZGUF/8RhGo1e8ff669EPtiTEsTdFlrG+7dj65UDYzy4/c252Owt+NDrWwpo4uHiPIAR4XwVg4BWMlfx8gz/Tb3eYJbGlYhJmFgO715ujuZFWC2X+1usicYhHob67Q0o85LAv0wdT5PmgcXGopV15vNdPf6IlArVPRBq9HD6z85eMsk60HCo3B/5EGRXvyDHWLhEDz5pLO8RxWwirUj81UOtRL1eZ4= 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 10/21/26 04:49, Kaitao Cheng wrote: > > > 在 2026/10/20 21:58, David Hildenbrand (Arm) 写道: >> On 10/20/26 15:31, Kaitao Cheng wrote: >>> >>> >>> 在 2026/10/20 21:07, David Hildenbrand (Arm) 写道: >>> >>> It does require architecture support, but that doesn't seem practical, haha. >> >> Well, but that's required when an arch wants to rule out all races. >> >>> >>> >>> Do we need to check both before and after the copy? This feels a bit >>> redundant, and I'm not sure whether such a small race window warrants >>> an additional check. >>> >> >> I don't see how checking after the copy makes any sense? :) >> >> You already crashed if there was a problem, why check? Or what am I missing? > In cases such as transient errors, software poison injection, repeated > bit flips in memory, or bit flips in the ECC check bits themselves, a > page may be faulty while memcpy() still completes normally. If the copied > data is correct, only the PG_hwpoison flag is lost during migration. But > if the copied data is corrupted and the kernel or a process subsequently > treats it as valid, I think the consequences could be more serious than > an immediate crash. However, I cannot estimate how likely this is to happen. That's the point, me neither. I'm happy to perform checks before access, or after, in the default copy implementation, but I want to have properly documented how this makes sense and which races exist. -- Cheers, David