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 A926EC43458 for ; Fri, 3 Jul 2026 08:55:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 714BC6B00B5; Fri, 3 Jul 2026 04:55:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6C5C76B00B6; Fri, 3 Jul 2026 04:55:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5B4386B00B7; Fri, 3 Jul 2026 04:55:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 296566B00B5 for ; Fri, 3 Jul 2026 04:55:54 -0400 (EDT) Received: from smtpin07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 958EC40492 for ; Fri, 3 Jul 2026 08:55:53 +0000 (UTC) X-FDA: 84946857786.07.3F934A9 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf05.hostedemail.com (Postfix) with ESMTP id BAFD0100008 for ; Fri, 3 Jul 2026 08:55:51 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=nO2wWJc+; spf=pass (imf05.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; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783068951; b=gSz4iWtsLlHYU2bO6B5E8W/oAjyh5h66X39DHo6cVMZ+EyiBVY/D87nhcRow2l5FiAVRR/ cTwJgxYAbH9AZjc7tvJW8xhIqLQ6Bg27umfrafBnMh+DbU4EoY8ZaT5WCSEsQurl4qNF1c bC16DNjw2CM+qd8yVOpnp6lwPusLm14= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1783068951; 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=EEAIxGo3dSJkTAzBCYyz7+REaEPQc5JW3M2g45BlcbE=; b=QFeNyMNl+ofjLnmCCOM84Y8Hl8TVJ1aA0GEEEMyvtvDzLxbrgoA8KtlnDJFYpQqiX2chZ6 udI6xF0tJ7lriFWEKD1ewMyhr8OeqKGXHaC79r4SUE4VqXmAsx08NOEcYHZTt3tIcvz+qQ ms9j9F+af7afzkDLEdxIx59jKjb4ELo= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=nO2wWJc+; spf=pass (imf05.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 E872843E41; Fri, 3 Jul 2026 08:55:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC03D1F000E9; Fri, 3 Jul 2026 08:55:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783068950; bh=EEAIxGo3dSJkTAzBCYyz7+REaEPQc5JW3M2g45BlcbE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=nO2wWJc+OGUvcDuRDWvA5f2xoxAapUk+jOR6wqN9Q8KTBq4ZCwPiazdcS04JTYZqt K+WSxsBHmp7Q0WmCM9AF12WKawU2/78Ye1IK6xX1ffAEGraXbx6KSjsodMejbxq/4v ONF/GHuYPud8kz6/ZKBYhiP0xQDv2ujeW7Bfz1fSQOjRcZa9YNC+sSflb1HEE35AwI p0YoSkDzVziObh6vtjdciRdl+2w21dNPqqbzkvMRldI8Bm91G9vKMWKh71BhdrY9jM BaY0LURdzmSo3+C15mhbnKiy6fUsRWTdznz2wHQseCZVx/3XAZN6u8WnD0Er5Onr5C aBltWxv0jOUDw== Message-ID: Date: Fri, 3 Jul 2026 10:55:42 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH stable] mm/khugepaged: write all dirty file folios when collapsing To: Pedro Falcato , Andrew Morton , Lorenzo Stoakes Cc: Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, stable@vger.kernel.org, Alexander Viro , Christian Brauner , Jan Kara , Matthew Wilcox , Song Liu , Eric Hagberg , Zi Yan , Gregg Leventhal References: <20260702165409.164568-1-pfalcato@suse.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: <20260702165409.164568-1-pfalcato@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: BAFD0100008 X-Stat-Signature: a3hfrbj615j6gf1ngkdga17stu1t9ojm X-HE-Tag: 1783068951-460886 X-HE-Meta: U2FsdGVkX1+/u6wEGhIPnlaFKBS307U7T0AIt8CjzDIB3h8ioqhpYaH3/w0XuXfp05CPmbz4Qa7UNxyg1XNL0si7gV+Ucs7YwMYJL5uasyqZXDk4x6VmLMyWltuRveqwxPfRDiBcXDmXOBwpCYfikUu3MPapqU31wINw7AaKPe84Ismb43LwRQ5d9Yp2+qJ41VlX9P3Z+HLp0Fw4xEeg2BeHFx4x9dXgr0gnFA96UVw8la7K84oDoPaDZzMpsu8jSFkGAyS5tDPzNP+8RedU0VDi9fzuomo8g0Pw9kJmg0Zt3UafBRc/diteEfb7Cd/XgbGTBdqowQa96H2jkBSE5UrWORt9V+IQrVFyuqgeu9ROzrd8UeFtUjRF+6Es8Rj3XwOcpLUrz3l8HFJrqRep5MphsZHCRuSJjha9RleK/au2Xx65LDdBNH11NZwvgx3ha+pp17HtT067IqgQ/i8xWcny1+tImlpT7GGemEFw4V/CFntubbatB+pvXGQRfRUJlIxZILGA+LsfWYz93yFO4H6F9YQel07HFY0iwD0Oq2ZRyRoSi8xALhLMEg2rcKNiL1k2tTeznnDyfcpp+sIUPIJCoEYljE++WogAZksjXLDE7ai3A5Rjyl7cbOQFYChDqLC4GihAINCemr4JrsYrm5z3gk+EIyANuVPDJknlxyXAQ9lmXjmISb6tyBAFU7UTQfwv5/LIVjWwPyAiQIWGSAq/DVim0sxsdn0qnP/p4UyX++v4jTzJcRMlFwWOeaVxqh2HJXWU+ZNiqXp6ZVt25gCJj2hrOKyQRw99ESCT5SFiRJlrAY9MoK/Wf9LWWcTQfggTWaeZsEqwgec5Ka1TD/TCk7rPOYz8TmU9dVFpsUULvwvM38NVKlOx2AO1a3M5RFBIMI5M5hqft4glNwvrC1k58QSaoTKh1MZPpjMi4s1j0qLZdsoyWLOUmU2aNnW+melZG95w/gyz5+kwthY BOnSKEHk LPEhWQr4jlD+d/MlpvbnRsswFD44wKpZk7vzGbvYdc3aWnqCXd9t7up+yf0FLX8vQOPVNeAy8Z+FmHpXLcWU7az/YaJ7GItOyEO182KCrKxg0EBbYuvhucceutaoKw3ccQibLgaGHeoj68fXX5gp9d80NWJfEysMYBOVohhkXKzE+cTgiOvnN0w1Cpscvo4KDuYdIewdSUiTZUg4hRE/z9MyYMa62m3cHMzInYcC2EZbqw/N+7bhFtviH8quLuPBiM5MN2KT25FhtNVw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/2/26 18:54, Pedro Falcato wrote: > As-is, khugepaged and writable-file opening exclude each other. A file > cannot be open writeable and have THPs (because the filesystem is not aware > of them). khugepaged will never collapse file pages for files that are > opened writeable. On an open(O_RDWR/O_WRONLY), the page cache for that > particular file is dropped. This is fine because nothing could've been > dirtied. > > However, there is an edge-case: collapse_file() might not be able to > coexist with concurrent writers, but it can coexist with dirty folios > (from previous writers). Therefore, the following can happen: > > open(file, O_RDWR) > write(file) > close(file) Okay, folios are dirty. > madvise(file_mapping, MADV_COLLAPSE, some non-dirty range) collapse_file() has if (!is_shmem && (folio_test_dirty(folio) || folio_test_writeback(folio))) { ... result = SCAN_PAGE_DIRTY_OR_WRITEBACK; goto out_unlock; } Making us abort collapse. What am I missing? -- Cheers, David