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b=Ye8RwW2d7GDmAxjfmzVlZXjSvre6TLxVpfc43JKhWXtLMpy6Ouma/DClWqRLIq5eB UAcW1HQZN5IfBulAPNrUM62ALzdQLG9ZWkUleO73vXGB8usXx2rFJO4wmD1Ui0QqwZ vvYvdclQMZpe06/RaSzWm+tFMBNzelACkigUIMf+77HATpuiPmmanE3Om4NsqVT1lW Lcaj+lFQ4r4HvwS8WnqU5EgkpQeIP4GEPJaupYnem4VKElMgbf9gWgrCvogPwCxC/2 bmGmwALZknPaG7/HKniNQ/fs0+UolugZMREQgrD83VYaMk5vezvVmpbG4/t0Mv/Evw I1gcRDzynCfsA== Message-ID: Date: Tue, 4 Aug 2026 18:54:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC v2 PATCH 0/16] Optimize this_cpu_*() ops for non-x86 (ARM64 for this series) To: Linus Torvalds , "Christoph Lameter (Ampere)" Cc: "Lorenzo Stoakes (ARM)" , Mark Rutland , Yang Shi , Ryan Roberts , dennis@kernel.org, tj@kernel.org, urezki@gmail.com, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jason Gunthorpe References: <20260715180455.515692-1-yang@os.amperecomputing.com> <0344c559-1959-4531-9265-d5a5180eb7cd@arm.com> <25d1e09b-53e4-7cd5-87db-b58437e4e690@gentwo.org> <4887267b-dc26-4c33-96ca-8dff054a0d1f@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-Stat-Signature: orf5asfzs5xmyaey98fgt69i9fxi75s3 X-Rspamd-Queue-Id: 05738C000E X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1785862489-52997 X-HE-Meta: U2FsdGVkX198KWH6mQK+ndRR/zy9hTeK7AwdGjOQ8GuOwZIiPfQMoeUyNpqdyj0AgOeK2JxSccNqyvXbrNGR6ofK2QEPAjqCaHii7d/YJf/V2OvaQ9CZclBzIDUFNCmLSUgZacxJWHVvbNyGrTpE5M9cz7KsTYXcA/NyqCmNOB/PK8zvdl3ozoa5CHGUnyYN07e0OFBCFiyaAxsEpj6yjsYp4W1r+ZKrOAEqikbYW2ffjQA39qkQURm2wCIRRlyxSYMJN0HDd3ppi3mS9SGBIASrUsyZ0tEL5PtYOOw1r82R59DRJS0Bgn6qmGJ+Mt67HDyWYEWUObe5V3LTvfzlhl+D3yBOvo6hLZj0jBb8RYvkOzt869oybC5j4Y50JEsps61C4ZwTbKj2GXUGZ12GfrE2Gl/mzBeIZ4j8C+hthhkxd2H+bv0sC7BfdZCvQjJKJ8SO2BCzPgHw0B6/0JMerzYyHlwoLCdn3qHK/2GKOxHWJ7w9sJqGGOiT/Y9jupWh1aQPyDhJMu7MOyo/5MiOYUwEDfz6m3s0J0/o2JozF0g0MWeW2o1YYVgUVdDvPHqSqQp3/qkxyPP8n88fRsLVo8RXFI5OOAVfFaGA1NNXD/DLbjG23odDAdewxeJ5z7X/q5bqDPpIjzmyJee8lYm9qYkAZ2VlRHD/C4szhh8X875b+TcOMvclkEnqKABpeg9K9qfauNfmY1p/1vRBC2I5nkhBtKppWLKcvgxO+GdoY32u8xPeXhD9k2Ul2pWES426Ytm/Hgq/+Fr97yRjCpzD8XXDopyJ8mK98bAvscdSxi738wzxel20BvclBLbUTsCS6O4YkIaf2ApAknya53mHRXUUpgeiqzZiOuLCD6+gEhpcFHVnj54RJgTRi+zC0M/HWLAvWyZste4W1KtbOQT1Pcr7PCThxmKIAtk0+Ax3j+hiNNC8p6EHo6w10S4oJTuYlREB5x0hHKF/eyy2RLk MBAvMHwQ BHBcl5E+FBapoxwFM/jSu4ovsZBOo7h55yRM/MeYafRA8QLmqULy9vriogZIDOopd5BS/JfqH4hSLOa2eG2G+rN6bBYwHu89S5tJjaeSBBccuiu8ucvqpv+hyuojMUVSNYs/5RHIgN0sfFHTnTu6PFVFB5KtjC5oHqERYOwwoD2tF8uQ3Cv3ng8G0YOv6/ES4ElG3lQ4YmeqSjb0U8lT9RDM5Nj4psLqKaI6WPjamD5yr0hHK1/c3bqb/Gmz+FUhVbKwT1RgEYccawB+IX3eAyDRAUWTWOuLW0dGirbGGHGhWeYq5jhlU4LvFjCbvewTHM5TBUTqlN2wT5BdTqCBcxdLf6Kk82a9SGYgyXDx7Up4AnyO21t1RsaEiAG+9ZjEgrPY06EDbz04qfCI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/4/26 18:30, Linus Torvalds wrote: > On Tue, 4 Aug 2026 at 09:27, Christoph Lameter (Ampere) wrote: >> >> We certainly do not want to replicate that approach. We are using the per >> cpu page tables to avoid address calculations in the VM that other >> platforms can do with a segment override. > > Right, and I said that that's ok as long as it's a internal > architecture thing. Not a "this is how the VM works". Just for completeness: I claim that things like "kernel text replication" are a completely different beast that we should not even put into the same bag as what is being discussed here ("using the per cpu page tables to avoid address calculations in the VM that other platforms can do with a segment override"), in some limited internal architecture-specific thing. (I assume some people here don't realize how tricky kernel text replication actually is) -- Cheers, David