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Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0XDc33Cj_1793065231 cluster:ay36) by smtp.aliyun-inc.com; Tue, 27 Oct 2026 09:40:31 +0800 From: "Huang, Ying" To: Yuanhe Shu Cc: akpm@linux-foundation.org, david@kernel.org, Kaitao Cheng , vbabka@kernel.org, ljs@kernel.org, liam@infradead.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, 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 Subject: Re: [PATCH] mm/highmem: refuse to copy hwpoisoned folios in the !copy_mc fallbacks In-Reply-To: <87pkww7lnl.fsf@DESKTOP-5N7EMDA> (Ying Huang's message of "Mon, 26 Oct 2026 19:21:02 +0800") References: <20261026025724.1430747-1-xiangzao@linux.alibaba.com> <87pkww7lnl.fsf@DESKTOP-5N7EMDA> Date: Tue, 27 Oct 2026 09:40:30 +0800 Message-ID: <877bj37wfl.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7DB101A0002 X-Stat-Signature: egmi6mtksk13pwwq7ozcfdrj1z9xg4iw X-Rspam-User: X-Spam-Status: No, score=-14.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1793065236-793518 X-HE-Meta: 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 t244hRJh eTxrm6KT63800tIZ8Izr2B2mx2YJircl34d2eCvmMRp0F1mBvqjpaLzTzK1V628xLspXtwHlp5YyeewyaYfqjz4Ub2xDeS5emKbY7izHRGTLxwa2cq3HLGSGGLDsAr7Z/SzPPxr4+C8yNmctGOWerz6ZpBFDo2Ff7uccy+7UHf2biO/SUgNMT8+EYTGEXFFykU1dDtVj26hFQgWqgqTAMp00wtQCZtUY0WDoBp0Hepo9BI6QitJH0+inXArpB/JSgRi0j+ECZl25L9PU3OkWr41H7kipxZ9voh+zD7GxGthj9fY+NCiIzhiCG9R0tL0C5tkH4nuVPhFF/B/5i4wexdZJPjEnILBFzYj/ORJYUgRK3EDTAD6fOSLyMkbsM5VsS+xSXCctnlaPdBUeG4SB6e7NNA+BPPrQsEw73pfvTnPWbKIU= 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 "Huang, Ying" writes: > Yuanhe Shu writes: > >> Where copy_mc_to_kernel is defined, copy_mc_user_highpage() and >> copy_mc_highpage() stop at a hardware error during the copy, report >> the not-copied bytes and queue the source page for memory_failure(). >> The !copy_mc fallbacks return 0 after a plain copy instead. With >> PG_hwpoison set while the data stays readable - software-injected >> poison (MADV_HWPOISON, the debugfs corrupt-pfn injector) or a >> transient hardware error - there is no fault to recover from: the >> copy completes, the destination folio carries no poison marker, and >> the poison is consumed silently, the same poison consumption >> commit 841a8bfcbad9 ("mm: prevent poison consumption when splitting >> THP") refused to risk on the split path. > > As far as I know, software-injected poison is used for debugging only , > so I don't think it's that important. Hardware poison state in DDR is > sticky; that is, even a transient hardware error will cause a permanent > hardware poison state until a reset. > > Therefore, the primary value of this patch should be to reduce machine > checks (and panics) during memory copies. If so, we should place the > check code before copying. > Another factor to consider is performance; the change shouldn't hurt performance. Please do some performance tests and share the results too. --- Best Regards, Huang, Ying