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 9B599C4451B for ; Mon, 20 Jul 2026 08:02:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 567656B0088; Mon, 20 Jul 2026 04:02:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 53E9D6B0092; Mon, 20 Jul 2026 04:02:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 454356B0093; Mon, 20 Jul 2026 04:02:30 -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 0E9666B0088 for ; Mon, 20 Jul 2026 04:02:30 -0400 (EDT) Received: from smtpin01.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 6DC9B807B2 for ; Mon, 20 Jul 2026 08:02:29 +0000 (UTC) X-FDA: 85008412818.01.E2284A1 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf05.hostedemail.com (Postfix) with ESMTP id A3AF9100008 for ; Mon, 20 Jul 2026 08:02:27 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=R71isxJP; spf=pass (imf05.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784534547; 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=RQ77o9wiEXBxH/ExlbH5P0bZkq1tD1nMMK/F8/u/Cg4=; b=frAPZygmW0IQqV5z2PGTopEStbESA+KbPtAL1t6pdxQ11P/pepBp62Ctv4AypiCE5EkYrD 2U0WJCcvCgjCdyO9g9Vi16RGr0OaCslbRVdzGO68LBceOtr5M0ifR+VJQv4DMJVpN147rr UkDRQysfqeR8+96nABTXIkHyi1A4uhQ= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=R71isxJP; spf=pass (imf05.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784534547; b=rV/YNrn4Ient7Xdf7cYrMKfJYiRhdT7Qv0owYCuexYp5HQx68TbbsRGVYf6lbuoRjEFJqH y/VzahREjt0TqU4XmIbdT/JyBF62j78TbvBnU26//TUnENLEwGbWF9hb1xNynRnekgwt+b ImrkQXDlv2gK3Ut2CCbfukVhqe5f8Mk= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id DBFE740A9B; Mon, 20 Jul 2026 08:02:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3E8A1F000E9; Mon, 20 Jul 2026 08:02:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784534546; bh=RQ77o9wiEXBxH/ExlbH5P0bZkq1tD1nMMK/F8/u/Cg4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=R71isxJPQ/OTjpr4geErllAEM0L7sdpYyMmdyywpKcCPXSBYsLayO3DMyJab+V92Q m/QKP36IvakrXNcXR33fB+aJvLUxqUTd1FV+sL3iJLncbeLAk5XyCaYXO7qdW/KrDA CJuia/ETfMsoVDBIddpB/PtknpGoWt+oKeuH++6HIpC2d+pGqkzNWfRpoBXgggaxus HUYAI2DS3V8gbmA9juQsxCgXcieHUhyW2AZ1V9zqkarHhFt7l/MQJ6CX8Secn+Ad8k 4aWDHGqeSbzvJpAp1ARTaGSN7Wj/2e4ph9wlK/IWq8fUggR0avVYiwPq7KmiiB/vrI 5GbtuTLKuBzNA== Message-ID: <4d4fbb2b-dfef-4228-9e9f-f967aec4dfd7@kernel.org> Date: Mon, 20 Jul 2026 09:02:21 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [LSF/MM/BPF TOPIC] 64k (or 16k) base page size on x86 To: Nadia Chambers Cc: Kiryl Shutsemau , lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, x86@kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Matthew Wilcox , Johannes Weiner , Usama Arif References: <915aafb3-d1ff-4ae9-8751-f78e333a1f5f@kernel.org> <17c5708d-3859-49a5-814e-bc3564bc3ac6@kernel.org> From: "David Hildenbrand (Arm)" 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: A3AF9100008 X-Stat-Signature: 3omn3uf13tadun3up456hcxus3gpw9hx X-HE-Tag: 1784534547-235930 X-HE-Meta: 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 bLSgo/o0 DFDua9zJTSHHnOpwscOoZ9Nkb+9GM0YYZ+PExcKsXFoCy5O5WWGrf1muqAcdMyVzqjqz1qBo7XLsonrbYbys6yB+dU8DOyP3DzioSVTMQfq6QMt85auXo5b8p/HjJiW74J62ETuz6aKlufESFXJ+8+n4RVjrO3Tts25knx1B0f23Hyo8Z46u/xd95ptIqG8DVqDwlJXtpzojptxfPDyjSYyFk8pO6M5VsgZ/bs+/bVf7eJrxV8tzr5jmy9ToT3Q2129jAgH4Nje7SfPoipPrvDLOdPBpZsYX0CL1P30zTmwlHkU0pG3exYTrbacwsyreqiy1hNbr+sEbaaBD6sYL4cibmmw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/19/26 23:24, Nadia Chambers wrote: > Am Fr, Feb 20, 2026 um 11:24:37 +0100, David Hildenbrand (Arm) schrieb: >> Right, see the proposal from Dev on the list. >> From user-space POV, the pagesize would be 64K for these emulated processes. >> That is, VMAs must be suitable aligned etc. >> One key thing I think is that you could run such emulated-64k process (that >> actually support it!) with 4k processes on the same machine, like Arm is >> considering. >> You would have no weird "vma crosses base pages" handling, which is just >> rather nasty and makes my head hurt. > > While it had to be written, it was a straightforward extension of > converting ->vm_pgoff to being in MMUPAGE_SIZE (Kiryl's PTE_SIZE) units, > recovering offsets into pages usw. Nothing seemed terribly hard to > understand about it. Really, the code as it stands rarely approaches > what it's doing in such a way that it broadly surveys the layout of vmas > and pages and be conscious of whether pages spanned vmas or multiple > vmas were representing maps of of fragments of pages, so I'm not > convinced there's anything particularly unique to be afraid of here. Just to be clear: I don't want this. -- Cheers, David