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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , Brendan Jackman , Johannes Weiner , Zi Yan , Oscar Salvador , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Jan Kiszka , Kieran Bingham , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 08/12] mm/sparse: move __highest_used_section_nr handling Message-ID: References: <20260909-b4-sparsemem_cleanups-v1-0-008fc8d579fe@kernel.org> <20260909-b4-sparsemem_cleanups-v1-8-008fc8d579fe@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 809C21C000A X-Stat-Signature: cih4u7rxo1c89sr66tdeapgismyb3efm X-HE-Tag: 1789042142-638885 X-HE-Meta: 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 SjtHaTob KU1skqg/QhqgpAthBdkOWSYodpFH9nPa94GQT3PiAQvMoBEiPRfXvRUqWwsei16XYLQ/vj6Kqm23Qs6xqzi+nucxQZNuo7Wy00tYTngl+5IW7M2pnPBJsncjRnqk8hjWwB6DipIlu/h9HZUpQqMi3fDBB5c6AMlVuiwhqEoXO0Rjaly3GhCrYdFbo1AZY/wu0zDLUkSwvsDzEKehBuYWr5aoaZ0laeMki8GIVNRyd8+G74o4rC47MUmAyMIaz/Gao4URQC53b6uBliJg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Sep 10, 2026 at 11:13:18AM +0200, David Hildenbrand (Arm) wrote: > If you have something consuming __highest_used_section_nr while concurrently > updating it, you might get torn reads/writes that mess up the value on the > reader side. > > For example, mm/compaction.c consuming __highest_used_section_nr. Right, but I guess that if we get a 'wild' value, at least we are guarded by online_section_nr() performing the right thing? Not really figthing anything here, just convincing myself :-) But yes, I guess that we should fix this in case we add more consumers of __highest_used_section_nr in the future. -- Oscar Salvador SUSE Labs