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 284D2EC1EB2 for ; Thu, 5 Feb 2026 13:55:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8C89B6B008A; Thu, 5 Feb 2026 08:55:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A04C6B0098; Thu, 5 Feb 2026 08:55:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 79F426B0099; Thu, 5 Feb 2026 08:55:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 64B9F6B008A for ; Thu, 5 Feb 2026 08:55:02 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id EDAAB140543 for ; Thu, 5 Feb 2026 13:55:01 +0000 (UTC) X-FDA: 84410549202.10.02354C0 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf10.hostedemail.com (Postfix) with ESMTP id 3F7EDC0002 for ; Thu, 5 Feb 2026 13:55:00 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=VVxV9842; spf=pass (imf10.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=1770299700; 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=yo9DSR2LUZlbJ6nSls4wEgtWzOahzRwvPpN6s9ILNVU=; b=z4Vbn7sXkOOH9Ux4+p8RRfKUU9tDf3mqbwazPYveWCdrwU4r5fRjApFlksIj0G0taBgiVP M0Mw7MRa/DjfdShKl+UrBzxdXPB2977BooAwz7b87e88+WYxqHyEpeFonZdtQwYQS1dKuE kevs3tOKWXxT7x30R8/wDTfRdLBAOLw= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=VVxV9842; spf=pass (imf10.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; s=arc-20220608; d=hostedemail.com; t=1770299700; a=rsa-sha256; cv=none; b=fnwmQJx850Dfsqi66ygkw2cQo5KeylcaXsIyFS/c2I9zmBrpEL5+G2SLC9ffIDq2JA/kVE ftLwLIGZyu5BE4YMW0OZS4ZFYTETpRokqRZTaWvFUyAkECnhFvQl+Jtiyy/sSElUYrDF3x dVRE1+Zs6mNlT+tNLbR+aQu8xj8h0ZI= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 310E343C74; Thu, 5 Feb 2026 13:54:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00BBDC4CEF7; Thu, 5 Feb 2026 13:54:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770299699; bh=sFil3yu86GERvqyxBASqk6D+b92nzCIAxVRDzXFk5IE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=VVxV98426Dh4XEprkhO91xKxeVP1Npp1yUwzn3nwz3RVGemzysZC6GWZIpGvjw9jj QmSyc6sxsBqFRjV4mF8OH8LOYc675cgH1vSsOOGBsEvavV8rsZfEdh08n3Z9ny1swQ QIrrQJBoL3WAgulMHMBcV8GaAtZvYTC1wnWKl/Q2N7b1eBQpA+qqvTv5K87WGlWbfA lTFLgWuRrYh1ejR45a70HRnbd+9Sofv5aszwiUMTOB30+16EhwvH4vYVFA+6ES/1QU 7VSVmcUn+x1bqVi9f9woMoqXOdgGfGUOTgO90Wsrpw4q6gfowvKjxTh5WSmGQoWPr0 VXfHz2EgbE6AA== Message-ID: Date: Thu, 5 Feb 2026 14:54:51 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv6 05/17] riscv/mm: Align vmemmap to maximal folio size To: Kiryl Shutsemau Cc: Andrew Morton , Muchun Song , Matthew Wilcox , Usama Arif , Frank van der Linden , Oscar Salvador , Mike Rapoport , Vlastimil Babka , Lorenzo Stoakes , Zi Yan , Baoquan He , Michal Hocko , Johannes Weiner , Jonathan Corbet , Huacai Chen , WANG Xuerui , Palmer Dabbelt , Paul Walmsley , Albert Ou , Alexandre Ghiti , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org References: <20260202155634.650837-1-kas@kernel.org> <20260202155634.650837-6-kas@kernel.org> <1b80b189-b549-40ba-800c-8037ce12b081@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; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 3F7EDC0002 X-Rspamd-Server: rspam07 X-Stat-Signature: gpp9f71iyrwbk6ez8y335yksyqfx5uqm X-HE-Tag: 1770299700-212121 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/5/26 14:50, Kiryl Shutsemau wrote: > On Wed, Feb 04, 2026 at 05:50:23PM +0100, David Hildenbrand (arm) wrote: >> On 2/2/26 16:56, Kiryl Shutsemau wrote: >>> The upcoming change to the HugeTLB vmemmap optimization (HVO) requires >>> struct pages of the head page to be naturally aligned with regard to the >>> folio size. >>> >>> Align vmemmap to MAX_FOLIO_NR_PAGES. >> >> I think neither that statement nor the one in the patch description is >> correct? >> >> "MAX_FOLIO_NR_PAGES * sizeof(struct page)" is neither the maximum folio size >> nor MAX_FOLIO_NR_PAGES. >> >> It's the size of the memmap that a large folio could span at maximum. >> >> >> Assuming we have a 16 GiB folio, the calculation would give us >> >> 4194304 * sizeof(struct page) >> >> Which could be something like (assuming 80 bytes) >> >> 335544320 >> >> -> not even a power of 2, weird? (for HVO you wouldn't care as HVO would be >> disabled, but that aliment is super weird?) >> >> >> Assuming 64 bytes, it would be a power of two (as 64 is a power of two). >> >> 268435456 (1<< 28) >> >> >> Which makes me wonder whether there is a way to avoid sizeof(struct page) >> here completely. > > I don't think we can. See the other thread. Agreed. You could only go for something larger (like PAGE_SIZE). > > What about using roundup_pow_of_two(sizeof(struct page)) here. Better I think. > >> Or limit the alignment to the case where HVO is actually active and >> sizeof(struct page) makes any sense? > > The annoying part of HVO is that it is unknown at compile-time if it > will be used. You can compile kernel with HVO that will no be activated > due to non-power-of-2 sizeof(struct page) because of a debug config option. Ah, and now I remember that sizeof cannot be used in macros, damnit. -- Cheers, David