From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 26760C44507 for ; Mon, 13 Jul 2026 16:26:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7E4D56B0103; Mon, 13 Jul 2026 12:26:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7BC716B0105; Mon, 13 Jul 2026 12:26:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6AB116B0106; Mon, 13 Jul 2026 12:26:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 2F0796B0103 for ; Mon, 13 Jul 2026 12:26:37 -0400 (EDT) Received: from smtpin24.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id B5F1F1C8220 for ; Mon, 13 Jul 2026 16:26:36 +0000 (UTC) X-FDA: 84984281592.24.B0504B3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf04.hostedemail.com (Postfix) with ESMTP id 0870140007 for ; Mon, 13 Jul 2026 16:26:34 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="j/wWVPKT"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1783959995; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=4oSo8Q8M/HDQKQiotqOthLA9NEMRzPw5zmVE4LKJDjI=; b=zcedBZMgr9JDt2CBKPcw63CLrS9Ep8KhJGsBinq6mNs9q2beoCnqbRb0+Z1p2gVz3goPX+ 1c4gUCqEucVFOPOE6Zbz3rYNLk+xGHxkc5uFGB+AdwY9KbBS5kp0m7IzxAmYuWko9xKIwK jDOdPTEoSP4aUufV1vB9m5rS9sPpNvw= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="j/wWVPKT"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783959995; b=aiLaxzP+M6XeEbZfuezxk4KVydzm3u4LnhVxCjSjGgwXgN6+dt3PqQGD416dmrBLHKbItq gbegIbtymMcnBlfMEcaHXFCBBcCJDxe23u5j9OHONPOiakIiUKTIo5Kwg5pAZSsEzxxTuF ZVCWkCfBQ+zRhbyhixAvPd8Hrd8lHbc= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 2C2416132C; Mon, 13 Jul 2026 16:26:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8AA4F1F000E9; Mon, 13 Jul 2026 16:26:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783959993; bh=4oSo8Q8M/HDQKQiotqOthLA9NEMRzPw5zmVE4LKJDjI=; h=Date:Subject:From:To:Cc:References:In-Reply-To; b=j/wWVPKTi2yTT9K+qqP7blEbgxvBXpRJlGYEleVOdJY/ZkEhoBIwU1XYjxGWpoIdN mlS6Xlu2LM2QXPsfPsM+IAwCvbLnTk3PUIFLKAeSQKyasltc5nTKDN8FP+v5+XkUZt oMxHh/hBdgPEvK+o9M/a9XHrOuskaRHNBN+GAA2b23faueb2V+5Bzreu3fOlknCV3g X9mDV4OfSOsr58Xw+JFDKUJfvXypw26dMhAOyajWuLXAmB1PrYjlAOf7rtGN25iIL/ rCzb4NMtDX3G/agbRDAIFbc/H1Uo5RS/e34Ox8O6QnOgt1x71EyMVCwAMkKzkgYZBB TIXI8gpq6Bz9A== Message-ID: Date: Mon, 13 Jul 2026 18:26:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 02/34] ARM: mm: make 2-level pgd_t a scalar From: "David Hildenbrand (Arm)" To: Arnd Bergmann , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, Linux-Arch , kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, x86@kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, "linux-csky@vger.kernel.org" , linux-m68k@lists.linux-m68k.org, "linux-openrisc@vger.kernel.org" Cc: Russell King , Andrew Morton , Ankur Arora , Mike Rapoport , Magnus Lindholm , Christophe Leroy , Klara Modin , Huacai Chen , WANG Xuerui , "Kirill A. Shutemov" , zhangtianyang@loongson.cn, wangyuli@aosc.io, Thomas Bogendoerfer , Lorenzo Stoakes , Jason Gunthorpe , Catalin Marinas , Will Deacon , Ryan Roberts , Pasha Tatashin , Rohan McLure , Baolin Wang , Tejun Heo , Kevin Brodsky , Anup Patel , atish.patra@linux.dev, Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Johannes Weiner , Michal Hocko , qi.zheng@linux.dev, Shakeel Butt , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Anshuman Khandual , Yang Shi , chaitanyas.prakash@arm.com, Ard Biesheuvel , guoren , yang.li85200@gmail.com, Alexander Viro , Dinh Nguyen , "schuster.simon@siemens-energy.com" , Vivian Wang , junhui.liu@pigmoral.tech, Muchun Song , "Vishal Moola (Oracle)" , Nam Cao , Pavel Machek , djbw@kernel.org, yu-cheng.yu@intel.com, Baolu Lu , Jonathan Cameron , Coiby Xu , Andreas Larsson , "Liam R. Howlett" , "Vlastimil Babka (SUSE)" , Suren Baghdasaryan , Michal Hocko , Geert Uytterhoeven , Stafford Horne , Jonas Bonn , Stefan Kristiansson References: <20260713135614.1618183-1-yeoreum.yun@arm.com> <20260713135614.1618183-3-yeoreum.yun@arm.com> <2858abeb-4134-4768-9a35-a569d5c86e10@kernel.org> Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <2858abeb-4134-4768-9a35-a569d5c86e10@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 0870140007 X-Stat-Signature: 1iz58oednbtnsu31qjqw3c6wfm7hm48p X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1783959994-647500 X-HE-Meta: U2FsdGVkX1+eJZnMXXo5YOmljp2LZcWY6Jl9BRrrG5jommLcMImkFWxOGIpa0a9P2th0VbtMA3DmKaDFmoQ9gkEbQHzrlDqa0qDceIjqr2s7Blc/9QUiJsEGRjrdnfvI07Akf9XvZbkWPFgBnQHtjHio5RjvMleWio7uQSxd0C1h/Nr5epDkedlEHFQlz5/+iVlHBPnUPpVk6d0F/yx3YKEzxkWbUluCAfibe0i96BYyjUvEKHJxAv8Wn3EqV3/RTL+Hkd3wpFjyj6PZgdl5ghdTDb79CJUS22VnQrrob1IE5ARsHUBAiLMn6m2seA4M6tvJuVX64o8FGoJRR8jRDloy2RA5pbTi1bTgoYbC0awLAyMISiJfIHUfHr1/KvCXmA5quMjFgpVwZJjYku+tFCBnvZ2IgsbCVRqk9RMFh8PoKWYqm7A2Zv/u1bXE/PHADBzPQLRJkfkrB94IFCZB80d3g6TkWrD0HgEkr6Prby8tInuimoRXC/ZTaix4hZjEWz3zzgKTeVyhM703MGrSZmmxlRxNS1u51t7iyAWyKS9+65jDKW/UbJDgZS6FMH6AMOg3fznPITnrvEKiS6jSv2dLSi9S2Lky3V5bQSfhELopWeCFCTVZACD17S1cHkD8fudbpuWX04Ho/ywwR2GOXpppKMemm4CJllLREBADgWtoz+PjCUCFeKl34dpSKq3SubxjrQtjOP4jdwpZ9gZjgfXEeBG0QNnNnFRFS4SzI8AaOgU8pgrR7f/V+jOfftKBtT6/1Z/2G6YD8DfGrfNM6YUbqcY5XchQf5kLJMZHewxnRTTLevBktBu7dIKwJAr+yQ68e8iEhqttji0I/l0K86IA1R/1k7ZfZmOt/K9tR5aa/44lH6BTSQFGyZByCA9Ef8g3XqU357v804IqWYisJsUSMtQVt9BGMJao5b8OyJW+8c5anJ0E/X7s9CQGDNyh7tpSOnMDXkJHwX5JW/C aefgblHP jl55Ul0x//6BM9gjpG5r/6628SftI9qRz+03czIlpUY3W9X3krGugLw700Vr5AnohvroCUlDCrx0KIKAal0UwzvYezz+ZOVHl98YcNHSO4974TOGneOBGIvuBxUMa6Wm0+Ohcziwv/cX+rK31KT3EqMy1PrW7R8bpkCuHm6LkK7koB0KWlXpcrpQhwsH5nzeXFqKYJviMcaTwd6APcp5UT7etAAjYRjcnRgpUwDBH19KZQZDqD+EiV909elnFKe86fzvqo9K7ER8s3kplXYqHTqZnJQ4pS/Ej48jBGH1Wt9yUtisVYtklrCZCwFqVNq4gBN7GpgCqZQLZ3j/I3I/ErXKkwgfvJ7WkTgZ+cUQ1TKcpzEk5KBMJ2fA8aXhP+ryACD5jQnMOcpuQPyn/aOh1ONHhSg0Dvo0vw9FhgWvqX/5fHPs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > * | | > * +--------+ > * | | +------------+ +0 > * +- - - - + | Linux pt 0 | > * | | +------------+ +1024 > * +--------+ +0 | Linux pt 1 | > * | |-----> +------------+ +2048 > * +- - - - + +4 | h/w pt 0 | > * | |-----> +------------+ +3072 > * +--------+ +8 | h/w pt 1 | > * | | +------------+ +4096 > * > > So we interpret two 32bit entries as a pair (64bit value). Together they span > 2x256 values. > > Then we make PTRS_PER_PTE = 512, to iterate all of them (both pairs). > > Let me do some more digging to come up with something I can confidentially "with confidence", not confidentially :) -- Cheers, David