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[80.230.85.71]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-493b8c7b82asm18608955e9.8.2026.06.29.14.54.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jun 2026 14:54:58 -0700 (PDT) Date: Mon, 29 Jun 2026 17:54:54 -0400 From: "Michael S. Tsirkin" To: "David Hildenbrand (Arm)" Cc: linux-kernel@vger.kernel.org, Miaohe Lin , Naoya Horiguchi , Andrew Morton , Oscar Salvador , Andi Kleen , Hidehiro Kawai , Rik van Riel , Vlastimil Babka , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Hao Li , Kiryl Shutsemau , Byungchul Park , linux-mm@kvack.org, linux-cxl@vger.kernel.org Subject: Re: [PATCH 0/2] mm: memory-failure: fix HWPoison flag race with non-atomic page flag ops Message-ID: <20260629175149-mutt-send-email-mst@kernel.org> References: <0b5f8b4b-d7dc-4b79-9555-a5b36265f3a9@kernel.org> <20260629030657-mutt-send-email-mst@kernel.org> <4f5ba5d6-246c-4430-9737-e8dd8e4c5142@kernel.org> <20260629092856-mutt-send-email-mst@kernel.org> <54c8cbee-9b26-458c-93ba-5aa594f5d1e8@kernel.org> MIME-Version: 1.0 In-Reply-To: <54c8cbee-9b26-458c-93ba-5aa594f5d1e8@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: Ifvem2SAMMXitHxkhmjL2p_lI6yy_04UIyGGGjcuErU_1782770100 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 879BBC0009 X-Stat-Signature: pm3oz4gc418csotuhe7g7885mwifnnht X-HE-Tag: 1782770104-333301 X-HE-Meta: U2FsdGVkX19cY0VQEWjJrm22FuSSt+KM7DQgWq9ayUEDMLmvNqSyyAEbwo4NAH+QTH7tYAW4K61Z+WZ0Ws/8S/EAQ8QdY3+8+ut5SlE6uG8dzWJgZCn9FwS7MoNBTwrmfq32NIKJNk0E3xG5XJ3o+pF4TZigLMrQBecZnl+U6Z+Fk7+dBXC9Ln2q27Ax4f6IHpMsaqnS2cNKfcTqhbgDVWeDakdWJrdc43QqO2nwjPnFdFgMCEzTcWtn/CCBNlil7/80jToOlteZdBt7vxe1JixbkfMg3cO1Ss9br2O4574kpHXMr4FfyRasIm414DHf0IMipB2YQOJqSgk2Njs6bYUK8pAgPgYX2v7rxNV5W7ryr1CNRT0W+nwbHc75n8YIj/r5yxu8NDjF6pJAfgVO2+lQxoxHK50uM5c8INPH6KhCLDWG3uXONMeyd9Z6haoayTufEgcTzU17GXKe/IylQ+2vVl7CjAKnCHjHjwjaWSM/UBzHkq/6b+f1QfZYUnAW4P1paRVJH/4KF2lokHyDEs9O5JT0xBD5kVgCmSOujFY7qXUYAsw+3S7PpqxMgX8XJA+Hs5HQMz2cHc7JLdZu2VtJeLhytzTCjJiGjSx7shkcCKpxO4r1bRopPTEpzxttOv+O0t5mvGt9nxnvDturuB6CF/bcj3SFj6TYL8XmjFBDyk5qbwHWh1o05CTu8t0xLM1+xyQIfi1Hwz5+LBJLg3ElmJAnP4P7ASPYJShS5/J2WP8x8rrgez3dXDMs5zooGNUQWMBo/JMfo6B6Rd/+lh006bpSs6J9XQCtMomdJBTwkSew77yNcGbVsDJhOknl8YDfMtd3KdjWIY5O8KP8Y2aqaU5iZZgLd7mttHZ9BYThcsEk881AdB3gMVShZOWdX7jsxT0DTdcvogCbC3NnZHlAT/LW4bf+iSpEKaw2ACwrXK82yUCmyStS9Z8Mv7z8OCXT7JlvnjOy71KIvmk 9Nne5Poz 19JU+9FxFM4h+jpS9t8O73XrS95u8uvyQQZ0zloJ3qHPGSmQj/HgDSisUfElbz2EjxXrzVdyeQhG8QpqUZsZLGJutb/RasMjgPjM19Zn2ySORluVvMvH+D502CpZpL5an2cRpx2D1skv6AU3jCqEnmcdVvuNThwn3Y00/nuI9iWXSPkoE6xTQXcqcNqzTy0gUQz0fGWZKVIyHKYX6rnyNYLip5TrZSBFl0QMpJQ06SvMfRK5VUYd4B7wWZDDKHmjMw+A3wdyAr0rmReXOJbTsL5WPQOSZeRxE0b9nJgTHsfCDedRguOR1s35V3OOQVz16rKVU8+cy3OVu/NPaqmuHIoQm7lz01xUOQX+HVDntCvy8nuN3q3Xo42PHhZmCLRGf5HDxVwlfomY+2GtNq09yyluyIV9KbbEyGhvQ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 29, 2026 at 11:22:11PM +0200, David Hildenbrand (Arm) wrote: > [...] > > > > > And again, I'm really not sure fixing a theoretical race when memory > > is failing is worth slowing the world by 0.1-1% for. > > > > Fully agreed. Let's say, we just send every bad page through MF machinery X times, and hope the chances of a race are reduced enough not to matter. WDYT? > I was hoping RCU was cheaper (I mean, we were once told that RCU > read side locking is essentially for free ... well in some configs :) ) It seems to be, just not to the level where you stick this around each memory allocation. -- MST