From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793181745; b=Dcagfb/OtIHZeyV57rOklZLNzQM29tu6VsJTJ8TckGxRuj5cJdl+ytpejrbVXsyhqhNi jB9SQh2Zm2iX+Iv1hU/jih2muKn0ZeZ/poU9p9m9px5Il+/d8ehxnmNc6KaAEuori+fui Py19R9iBsLeXan4adb/NA79VnCkGipMGp8yuZj0cBsLn5CBZpTwgOZjPy8uD5uCI7tEbD Xfc9x/3dxpRlq0GOXh0pozIrw2J4pHvU3ltnx3kXPBrbax6s0DMo+u7u0p4xUnwWID0Th POk1KQ9HcFLfcgZzEGv7A1i2p9TBm1BgB45t8OTuWVUz1n/Y66zH308Wma4SCsIWRMw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793181745; h=Received:DKIM-Signature:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:Content-Language:Autocrypt:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=3n953/bJQ0btHDOtJumY5KvKx/uqtjyCpTyQ6fObN6w=; b=BcdszkkmWwXds8u5hqviKmqul1R4I/62xTghmGonNVhOmZS4VUyT5qzyco0cE8EB2yEB v2CSpz/T7gY0OvbitD2i8614aJsMh4n2tUUpQIEKcobZhpvernYC9/hZ3aY/2dy+bw+6l OKoFhsM36R6dXNHQUfSEolcWtf79aOMs6vYAXFp8ntJxyRyfzd7lxCrW18oPZJvk8tNSz iiHdjZyeVSz9IC308jxm/j4N6fm1MGGZPuMN7J7ipCrMEhF6Z6DBVW+/VJdjkmWkL9gbR DWigGtbxRpmkGFsLeRG6fuxZd/3aniUE8RPiE4IxM1dKDF1ZvhNo6dL10muJ2nZTvFg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=G2Tslwjr; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 140AE606A31D; Wed, 28 Oct 2026 10:02:24 +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 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-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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 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