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 1053CC55179 for ; Mon, 3 Aug 2026 13:12:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2309D6B0093; Mon, 3 Aug 2026 09:12:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2082A6B0098; Mon, 3 Aug 2026 09:12:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 11E876B0099; Mon, 3 Aug 2026 09:12:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id DE9126B0093 for ; Mon, 3 Aug 2026 09:12:45 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id B5DE9A0665 for ; Mon, 3 Aug 2026 09:34:48 +0000 (UTC) X-FDA: 85059448656.06.9019179 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf01.hostedemail.com (Postfix) with ESMTP id 02B6C40005 for ; Mon, 3 Aug 2026 09:34:46 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=h+KN6TcL; spf=pass (imf01.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1785749687; 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=382LMWt504+2jkfqSbYK7EUjiXjWZcpNaa+hKKGGLFM=; b=h9pI2X9r7p3Rg3hNPNahlIhRcU7dvuLULhZm2y9RUWP982Ew0huk2hG4o8ZfGJQW9owvG/ z33xXIvznx0ePEYRD0oYDpUeEzXGG7duLyAd/ze+YUGvrHFRltAg+Dtim6K5SvzMrJQfzG QyNA8Tz3Aixf2WcStSrZhHBoNiQ+17w= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=h+KN6TcL; spf=pass (imf01.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1785749687; b=0TAYfkjdTlVeujZA8nhhk0z1ICN1KA+nBFmzwAJd01/j4bxTk95KqS6IHH4vruU6Un/Gov nSuUQTfIuP8KG/6t6gedDmAr7VzY3d/yCPp7vaZZus3R1GI6bAIAfAU4lZoN0Mj9vrB0jg pS8bkeRVcppWVZB6dq7S2q/lfdnmwWM= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 56BDF60A69; Mon, 3 Aug 2026 09:34:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B33121F000E9; Mon, 3 Aug 2026 09:34:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785749685; bh=382LMWt504+2jkfqSbYK7EUjiXjWZcpNaa+hKKGGLFM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=h+KN6TcLykHRka+xeosMd5gaCISdNmI1P19kqrM8Tiw/DcRiI3i69fuenkkHVrWei 0MNjjo7PEi7K5845/dexpfVKFQreJo0po2TUOeCK2AkgJISKcwhoWjIJDgNSlLpDt0 7/NTrTewIVEEl/PTE1KnTZ/CLia86wzMih+xie3c+pjQgHCZzu/sfdQxxcD+lmYFIw yGYa+Y+hHDLfOwaiFpMYgVuMVx5oj4+WQxlsjtdseNBlApj0/+KVtrcFu+EOAKl+Un 4jzt4K/x0dWhJsL6siS6/oNjJ2HOHFXxXsH+rCfZgWkOYLpkQ8LlyVjhgDKPuaTBlF LEGXV+7FKEcRA== Message-ID: Date: Mon, 3 Aug 2026 11:34:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 02/15] mm: introduce linear_anon_page_index() To: "Lorenzo Stoakes (ARM)" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20260729-b4-scalable-cow-virt-pgoff-v3-0-e8ecfefea812@kernel.org> <20260729-b4-scalable-cow-virt-pgoff-v3-2-e8ecfefea812@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: <20260729-b4-scalable-cow-virt-pgoff-v3-2-e8ecfefea812@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 02B6C40005 X-Rspamd-Server: rspam01 X-Stat-Signature: utef17d1jt9d41pcdimozzx7ohhpdd6f X-HE-Tag: 1785749686-310305 X-HE-Meta: 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 0uxq0+IM 9EQA+fRPL5Xs96UvF9SJX8f0ga54fNiW6OQpgzw94bSE3fWQRb1oxtRipojdyYWb911u+4X78cvEpxQKgZW0SqAkBDoEcPi+6YMv5pHoYl3KB3NUZZPXPaD2YQaXz0rq3N7yV4vZOPgKgYFcR3AENM+Uk0onqOYIlYahYbpaSjoDq/IwzEq0dJQYtPt8ZhLbhjcebo/Ku4QJj5ezyxIKF1PMwaga/ZlJCLuaj+W/JpVIJ3ZuciA39pnI9fGm2TtjIKrfgM4zLlzY/W0b3QeDcbjxcbiwEZSf3l4Mav8ii0JxRe5Lu/cUeQ3Ad8tiYZgI5d7KYdAl7l9FKYn3+9FQsdrrPBFuSQqtgp0IS/s7lWwKjataKHAvKwMc7Bu3vaNE5gY4LLYsoPCOC6Hj3mZi4waLF+Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/29/26 18:48, Lorenzo Stoakes (ARM) wrote: > This function provides the anonymous equivalent of linear_page_index(), > instead offsetting based on the anonymous page offset of the VMA. > > It is valid only for anonymous or MAP_PRIVATE file-backed mappings. It must > not be called for shared file-backed mappings. > > For pure anon VMAs, this will be equal to linear_page_index(). > > Assert that both of these invariants are true In linear_anon_page_index() > and implement the algorithm in __linear_anon_page_index(). > > Note that MAP_PRIVATE-/dev/zero mappings will satisfy vma_is_anonymous() > but not fulfill this invariant, so when asserting this we check > vma->vm_file to account for this. > > We do not update callsites yet, so no functional change intended. > > Also const-ify vma_is_anonymous() to make it compatible with the > const-ified linear_anon_page_index(). > > VMA userland tests are also updated accordingly. In general looks good, some comments below. > > Signed-off-by: Lorenzo Stoakes (ARM) > --- > include/linux/mm.h | 2 +- > include/linux/pagemap.h | 42 +++++++++++++++++++++++++++++++++++++++++ > tools/testing/vma/include/dup.h | 25 +++++++++++++++++++++++- > 3 files changed, 67 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index df78847f5f07..64214191e7c6 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1556,7 +1556,7 @@ static inline void vma_desc_set_anonymous(struct vm_area_desc *desc) > desc->vm_ops = NULL; > } > > -static inline bool vma_is_anonymous(struct vm_area_struct *vma) > +static inline bool vma_is_anonymous(const struct vm_area_struct *vma) > { > return !vma->vm_ops; > } > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index c6fc783aaee5..259177544b03 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -1101,6 +1101,48 @@ static inline pgoff_t linear_page_index(const struct vm_area_struct *vma, > return pgoff; > } > > +static inline pgoff_t __linear_anon_page_index(const struct vm_area_struct *vma, > + const unsigned long address) Nit Usual "two tab" comment (same below) :) > +{ > + pgoff_t pgoff; > + > + pgoff = linear_page_delta(vma, address); > + pgoff += vma_start_anon_pgoff(vma); I'd simply do return vma_start_anon_pgoff(vma) + linear_page_delta(vma, address); > + return pgoff; > +} > + > +/** > + * linear_anon_page_index() - Determine the absolute anonymous page offset of > + * @address within @vma. > + * @vma: An anonymous or MAP_PRIVATE file-backed VMA in which @address resides. > + * @address: The address whose absolute page offset is required. > + * > + * This returns the anonymous page offset of @address, which is the page offset > + * the address possessed at the time the VMA was first faulted. > + * > + * For anonymous mappings, this returns the same value as linear_page_index(). > + * > + * For MAP_PRIVATE file-backed mappings, this returns the anonymous page offset > + * of @address, which is the page offset the address possessed at the time the > + * VMA was first faulted. > + * > + * It is not valid to call this function for shared file-backed mappings. > + * > + * Returns: The absolute anonymous page offset of @address within @vma. > + */ > +static inline pgoff_t linear_anon_page_index(const struct vm_area_struct *vma, > + const unsigned long address) Dito. > +{ > + const pgoff_t pgoff = __linear_anon_page_index(vma, address); > + > + VM_WARN_ON_ONCE(vma_test(vma, VMA_SHARED_BIT)); Could we test or COW mappings instead? VM_WARN_ON_ONCE(!is_cow_mapping(vma)); Because we must never have anon folios is non-cow mappings. [...] > +static inline pgoff_t __linear_anon_page_index(const struct vm_area_struct *vma, > + const unsigned long address) > +{ > + pgoff_t pgoff; > + > + pgoff = linear_page_delta(vma, address); > + pgoff += vma_start_anon_pgoff(vma); > + return pgoff; > +} Same comment as above. -- Cheers, David