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b=f38RuqRb/jrM+Gu/zWGyEm8U1rNgYFWSu/zmUMeOkW75CjJN0V0r8lVTqRQ6O2MjE pVE4GWkkJqIxi0tRj1fuPyDFE6oauN0qrnN0tK7dvPO6UigbDVzzNDUtOiXHd6dpUQ Zynck6PTGpALVUAjh/In0G+ob1p0AjWhqt7GWgvbbIpOtSQX8gheKNvmsSNB+atxPp BlVTBYARoKk+uEsYkYWJGb6uaPmmqvUxcY5R9aJLTSiuZhebK2uQbngYX+xBgY32UH lq4GW3AxC90fT1d6vvnnf3UjFmc4eQMwH/cR0sESMpsUbIpETaK4y9H1voydMNDoKm TPmbIt/gBWkgQ== Message-ID: <7ae258ae-b694-43f5-8244-688ddd2ec666@kernel.org> Date: Thu, 24 Sep 2026 21:21:01 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 08/15] hugetlb: Use the has_hwpoisoned flag To: Matthew Wilcox Cc: Andrew Morton , Jane Chu , linux-mm@kvack.org, Muchun Song , Oscar Salvador , Miaohe Lin , Naoya Horiguchi , Jan Kara , linux-fsdevel@vger.kernel.org, Christian Brauner , Jiaqi Yan , "Gregory Price (Meta)" References: <20260805210557.1118966-1-willy@infradead.org> <20260805210557.1118966-9-willy@infradead.org> <7608c80e-645b-4d07-bba3-ef45ee36fba4@kernel.org> <7a23511f-365f-436f-b934-6a520510409c@kernel.org> <6121136c-de9d-4577-a30d-f00dbe244e5d@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B885D4000D X-Stat-Signature: 1tdbr8i5ociit9m99gjdg89cbzxu7nzt X-HE-Tag: 1790277668-263489 X-HE-Meta: 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 5bN4Zfa9 OEt4FGWRFbd3/2Bxiq6MBRs/kWA88yX8DhqW0QPwTXEadF8/4OOHrwOxLcaJ62qkjlxgXUcuL44Fd887vQjcYC0WIM7fwL0SvUKfRf6iwvlHpZVZ/8DWdP1PRS7x41qp6lqRTdy4lvFPoy2vu7Ug2CDBWI28g3CJQ7Qhrdku51aQdxJC7o0ceCzRKVVIuKtGqJpXRyprhvmrZXcYpGC+X2gVdKI24ZdSmLd3UUfDe/Mvy1A/oBjh/72hmH77WGCU6M6ZaPjifA/7yLhoqMlJ+AkbxD0NOeTWqfQGND8ZCHbqpXJA9S7d7UsjeCS9of86oQ2d27HXH746C7M82akGOWQQMxFt9ETv8NumzdRx4yA3Ebx8T30Dq85orAIc1TYAE3LO8 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/24/26 20:53, Matthew Wilcox wrote: > On Thu, Sep 24, 2026 at 12:32:13PM +0200, David Hildenbrand (Arm) wrote: >>> Oh, no, it's awful and complicated. We could strip out the two bugfixes >>> which are at the start of the series, but why would we want to do that? >> >> Andrew usually wants us to separate bugfixes (especially stable ones) from >> other work. Unless we all agree that they are not urgent and can go in in >> the next cycle. I assume that's the case here. > > I don't understand that preference, to be honest. As long as they're > first in the patch series, they're easy to pick out and don't depend > on the other patches in the series. I mean, I agree. However, Andrew tends to fault in the cover letter into the first patch and tracks them in one unit. > >> I am not convinced about the huge_poison thing though, that originally caught my >> attention. >> >> So trying to understand the race we are trying to solve (that is independent of >> the original idea of the patch set), I realize that these races are only on some >> slow paths we don't particularly care about for performance. > > They are not hot paths, I agree, but they are user-triggerable paths. You seem to assume that any of the users would be triggerable by unprivileged users? Remember: you need to operate on arbitrary PFNs without taking proper references. /proc/kcore? Certainly not. /proc/kpageflags? Certainly not. /sys/kernel/debug/hwpoison/unpoison-pfn or any other software poison injection? Certainly not. -- Cheers, David