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 13479C55182 for ; Mon, 3 Aug 2026 13:19:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7E2E16B00B3; Mon, 3 Aug 2026 09:19:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 76D286B00B4; Mon, 3 Aug 2026 09:19:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 60E366B00B5; Mon, 3 Aug 2026 09:19:27 -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 368646B00B3 for ; Mon, 3 Aug 2026 09:19:27 -0400 (EDT) Received: from smtpin11.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 46A061406B3 for ; Mon, 3 Aug 2026 10:52:56 +0000 (UTC) X-FDA: 85059645552.11.C51604F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf25.hostedemail.com (Postfix) with ESMTP id 6EDEBA0006 for ; Mon, 3 Aug 2026 10:52:54 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=IkG4C3U9; spf=pass (imf25.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=1785754374; 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=xVzjQs3HFfWf+RuJQ4W4NrHFv6BkXFAG420ZywAGWLg=; b=ZhlZUWiX97sWfEWn/Pi8f/UFuvEat0SQjags926zKAiEt6LSJ5qPA7m5BhbFV6GhfOp4yH VOzNCZzLU3sNJgnN5jlwboCowRGZHCn55gpA6Q2hGc1+TQ1u+W3nFP9IcRSPwJOy+/SW50 S9R5rpAZy9yKL10B5caVrEKYcU5v0nk= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785754374; b=bbFt4L5bPo0Bs09TGUZTbRFoI0EZEKLzu6PWuToNz9J4elsk9BaN9Ukmj1FmmJKm+NHTxx cQgtxwIuXuO67HTZPoVKB2lEVekLu+35tCMVmIUWciCpIxOw9nd7EsIDkuc3O7tyR2CwL2 yTOTR223UzFK1o9FCI8eJR8m9yNGsEw= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=IkG4C3U9; spf=pass (imf25.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 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 76493405D9; Mon, 3 Aug 2026 10:52:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00D6E1F000E9; Mon, 3 Aug 2026 10:52:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785754373; bh=xVzjQs3HFfWf+RuJQ4W4NrHFv6BkXFAG420ZywAGWLg=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=IkG4C3U9Q5nzyqNz6vG+sRjzCiegmydkM/traJZfxUI0agHFbx1RfrYvaT+Zl8jL9 fiihX4iWNoFjmP1NE/bVaF19K1Y+CmltIcfa5yVu4bj7zam3Dgl8NfWz3p3D7lilC8 gFOlwXmrD1U+DpFVHh53sTMYJphFYYzIxKZ9EmC8lnd9BxURflFXD5fJOFHzyj7T19 Z0RNVlGSfhEs6mdd22ZnYaOrqcjrAqu74XomLemSL/QKo4iDNd50DrQud4ggXKVXyf QU/qF2RPHdTywPbO4YY5W0U6wm+qOD9vBJB6Oi93N8eWViDHrqFT9MopxTP81kRjKx 4SOffAXcClgJQ== Message-ID: <4ad4b17b-bae6-4169-8649-bff4a29e7fde@kernel.org> Date: Mon, 3 Aug 2026 12:52:42 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 06/15] mm: propagate VMA anonymous page offset on map, remap, split + merge 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-v3-6-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-v3-6-e8ecfefea812@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 6EDEBA0006 X-Stat-Signature: u76nzws9c5brgw6s56xs95rrzzxz1ceg X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1785754374-735089 X-HE-Meta: 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 bzqwyp8+ Pf2bf10EbDTABJ4G+J9ZxPwPCzkR3KBKQ6OzKhGK+MeyPpwnO6J6nT0KCMx5HaR6NENePDuWtgsePfnI9C0RQtEYBLaBWG7kOlVM0g/RD85A5d7aZt5FynPsun2w8GautiYrmtU2lFqfcfaSCD/rCUvzziGUPZUrVHogpxrqei5ICpSJDdsLwLr6QckCf7wscFIi/c/gLRRUxpp4VR1/BZitgfqcYxckTy5o1+kLjwUwwXroC0Zm0IagaJOwdWhW9q3wJOjAY/PIM9Q6BpHTVbThC9MdB/av5gN5+V3xI/UGmTYzkMOQ6prEEKvfXcMdV7Vv1WcRYrO89u3Naq/1gNFrdMNojeWjK9ziHBL6Olhbov0Y= 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: > We must correctly update VMA anonymous page offset state on all VMA > operations that would result in it changing, with special attention given > to remapping. > > We cover most cases by simply updating vma_set_range() to do so (with a new > anonymous page offset parameter), but also notably must update the merging > and mapping logic to propagate this parameter correctly. > > The remap logic remains the same - we may update the anonymous page offset > if the VMA is unfaulted, but now this applies to MAP_PRIVATE file-backed > mappings too, so we update the code to reflect this. > > Note that we use __linear_anon_page_index() upon remap as the VMA may be > shared, in order that we update the field consistently regardless of VMA > type. > > Similarly, pass through anon page offset to the merge logic, updating the > vma_merge_struct struct to propagate it, and also use > __linear_anon_page_index() to obtain the anonymous page index so it can be > safely used for both shared and MAP_PRIVATE file-backed mappings. > > Finally, we update insert_vm_struct() to correctly set the anonymous page > offset on insertion of a VMA. > > We simply ensure state is correctly propagated here, so no functional > changes are intended. > > Also while we're here, replace a VM_BUG_ON_VMA() with a > VM_WARN_ON_ONCE_VMA(). > > Also update VMA userland tests to reflect this change. > > Signed-off-by: Lorenzo Stoakes (ARM) [...] > struct vm_area_struct *vma = *vmap; > unsigned long vma_start = vma->vm_start; > @@ -1919,11 +1929,14 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, > VMG_VMA_STATE(vmg, &vmi, NULL, vma, addr, addr + len); > > /* > - * If anonymous vma has not yet been faulted, update new pgoff > - * to match new location, to increase its chance of merging. > + * If a vma has not yet been faulted, update its anonymous pgoff to > + * match the new location to increase its chance of merging. > */ > - if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { > - pgoff = addr >> PAGE_SHIFT; > + if (!vma->anon_vma && !vma_test(vma, VMA_SHARED_BIT)) { Could we also use is_cow_mapping() ? > + anon_pgoff = addr >> PAGE_SHIFT; > + > + if (vma_is_anonymous(vma)) > + pgoff = anon_pgoff; > faulted_in_anon_vma = false; > } > Acked-by: David Hildenbrand (Arm) -- Cheers, David