From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 664AB606A31C for ; Wed, 28 Oct 2026 10:02:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=G2Tslwjr Received: by kanga.kvack.org (Postfix) id 1C40E6B05D8; Wed, 28 Oct 2026 06:02:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 174A76B05D9; Wed, 28 Oct 2026 06:02:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 03C406B05DA; Wed, 28 Oct 2026 06:02:27 -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 CD2756B05D8 for ; Wed, 28 Oct 2026 06:02:27 -0400 (EDT) Received: from smtpin15.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 652CB80BE5 for ; Wed, 28 Oct 2026 10:02:27 +0000 (UTC) X-FDA: 85371595134.15.4793FCC Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf04.hostedemail.com (Postfix) with ESMTP id 9C99240004 for ; Wed, 28 Oct 2026 10:02:25 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=G2Tslwjr; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 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=1793181745; 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=3n953/bJQ0btHDOtJumY5KvKx/uqtjyCpTyQ6fObN6w=; b=Cj5DQKMWfF7XLvVyhWUlZXconAnLIOyQ52ecFWXy0QVRSS5G4OXe7VFY7+zxZJXAUZpbfL DVLJOzkpGQ2BsyG91QEY3yGBkkVJXBP1JnSNOm9+E75a0Q36Q2lGb+HOxZllZE/bBTHvur Y4v50DepOYImFoVaZijahlwezi2Lyxg= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=G2Tslwjr; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf04.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793181745; b=0dp5CEM0ayzOhHh2uGjZrL8vXGNfZ0FpoKaBx3ixL/6gfbtZL2Lf5rflIUdxl0edZ3mw4L QMY9kRAAsyOiUSPaAog0iS7iuQ2mh2aixBNQVFryqsUyApn//F2xJXzVcvuz99ajpx+4SD oZu0RmG/mvAwUVhXb2JE5mXKiqmpSO0= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id C554C43C8A; Wed, 28 Oct 2026 10:02:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B35F41F01828; Wed, 28 Oct 2026 10:02:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793181744; bh=3n953/bJQ0btHDOtJumY5KvKx/uqtjyCpTyQ6fObN6w=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=G2Tslwjroiey1nXwhnz/Bg/e189Wku2yPdsY3XhKVv5NbMWwZhpYcK1j/YvlCIhNw 6li/12Jj/YclcnvqAbLihLUYVJldYiJ5N20/WXIbocbtr8NrYyzXP627oCUbDyt3Id q3+5sEaKE3PdwOX/e9BQ9kjJr/IB75kCTy6ql7LacdoEFf2puIIVDbdRpDm8tJUY70 wzSqI2ZCq0rvyqIzpxo+D4gZauu1UWI5Z+cRscTufPxIGFTv0eN0kcTVQ0h22ZA2Pt GShIgPxlq33tac2KoGfYAazGLaSiDHGBUFsq13dTBKBmMQ/FGrO2fhq3uY2LHq41Ox nhUMk1fPA/Hgw== Message-ID: <5dac5fd3-c2a6-4e1a-98fa-0fe1936b269d@kernel.org> Date: Wed, 28 Oct 2026 11:02:17 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/4] mm: pass the number of PTEs to move_pte() To: John Paul Adrian Glaubitz , Imre Kaloz Cc: "David S. Miller" , Andreas Larsson , "Matthew Wilcox (Oracle)" , "Mike Rapoport (IBM)" , Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pedro Falcato , Suren Baghdasaryan , Michal Hocko , sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Magnus Lindholm References: <2bc50d2a6829b49ee909e5bb943244859661a40b.1792609488.git.kaloz@kernel.org> <409079fe-ab52-4389-9fe0-d7246eb27bad@kernel.org> <20261027212610.6798-1-kaloz@kernel.org> <20261028091631.8072-1-kaloz@kernel.org> <25f5cbed-9126-4870-a81e-65099155bc9d@kernel.org> <8d4993cb2f2e5c3300514f1e2616e4a101488883.camel@physik.fu-berlin.de> 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: <8d4993cb2f2e5c3300514f1e2616e4a101488883.camel@physik.fu-berlin.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 9C99240004 X-Stat-Signature: pdh16ettru4q5g4fmxdzdh8f5nk5gwa4 X-Rspamd-Server: rspam04 X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793181745-592997 X-HE-Meta: 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 CQ2el9RH uJ5zLrfTaN1joLBH7YMGLvjYdiRWSZsC9RNM+SvjyxL7vTdCl2KHLmhhG5xDShOdXkQmEhMzIBW71iH7qmT98WjaLiCEOMyfXbah74WFHNJC8HCLHwSjQvSnhw6GlVp2BvaaTEWkLdWy+F3I2HRvveLiZVTPGvPfIKr1ePz3IIpmApXSQDqG1ExZRrGWrW0pyoLSWYDQ9jUAwiRyYqvH7rBeH1rqsPkjIKn+cvitASXbjU/LRqXEmP7alrXBX5PGV/CdNfd5jLyApSu5ItIcG/4kGUzxx6YgrzutzRMWEIzOgdrf19ZXcRvOfMA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/28/26 10:58, John Paul Adrian Glaubitz wrote: > Hi David, > > On Wed, 2026-10-28 at 10:22 +0100, David Hildenbrand (Arm) wrote: >> On 10/28/26 10:16, Imre Kaloz wrote: >>> Hi David, >>> >>> >>> I'm one of the museum folks myself, though more the kind who loves >>> running a modern kernel on old hardware than the kind who complains >>> about it :) A lot of these machines are still doing real work, and >>> these days not everyone can, or wants to, just buy a new computer. >>> >>> Some of us spend our time keeping these platforms working, and I'm >>> not asking anyone else to carry that, which is why I tried to keep >>> all of it in sparc. >> >> Okay, so mremap() and reclaim memory performance concerns make you sleep bad at >> night? :) >> >> Don't get me wrong, I know that running new kernels on old HW is fun. >> >> Last week a got upstream Linux running on a 32bit x86 notebook from 2007 with >> the snap of a finger. Everything just works (using Alpine). > > That's cool! > >> I couldn't care less about performance. Nobody should. > > Well, try to put it into some perspective: For some people, old hardware > is all what they have and given the current high prices, I assume many > people will be stuck with old hardware for a while now. Think of developing > countries as well. sparc64 machines?! cmon > >> The biggest problem all of us with supporting old hardware is the maintanance >> cost. Not just core-mm, but also things like ad-hoc page table walkers you are >> adding we (from core-mm) might have to touch at some point. > > Well, but if people are using it in the end, I think it's justified to support it. No. Run stable kernels. > >> If there is no good reason for the complexity, out it goes. > > The patch doesn't really look that complex though. It adds an additional parameter > to move_pte() which adds a few more lines of code. Not really overly complex, I think. Follow the discussion. > >> Because otherwise people will push more and more for removing legacy support >> completely, and that's not what you want, right? > > I don't think it's fair to make the kernel exclusive to very recent hardware only. "Very recent" find the mistake. (sorry, I'm unusually grumpy today) -- Cheers, David