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 0862310ED661 for ; Fri, 27 Mar 2026 13:46:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 76CD66B0095; Fri, 27 Mar 2026 09:46:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 71DFB6B0098; Fri, 27 Mar 2026 09:46:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 60C906B0099; Fri, 27 Mar 2026 09:46:55 -0400 (EDT) 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 4C18B6B0095 for ; Fri, 27 Mar 2026 09:46:55 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id B6B0C1610C9 for ; Fri, 27 Mar 2026 13:46:54 +0000 (UTC) X-FDA: 84591968748.10.2D719F2 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf02.hostedemail.com (Postfix) with ESMTP id D4A3D80014 for ; Fri, 27 Mar 2026 13:46:52 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Skms378B; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774619213; 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=yWAw0CsHYqSDWe4efm4Eod3arXmDkUR/GwfpXxf4AHM=; b=UaWLruZ2t945fWnukZOn5zRe8OXW0CjuRexhkHmDEwSXQlMulEXxSbAS9v2qAylrFXuJ5x tfLH5OyzoyeB9By5s5KC/FN1WB1P5ZtJ+Q09to4aOJftNt9Auo0+G5v4lEwbTtoEwagYf3 y9qfmrSFEtANI0l3AKM268s5mTMw098= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774619213; a=rsa-sha256; cv=none; b=Ry/JrRowZVVKlF5PAGUYXhmr8FUOLWLBfLvebaVGm6m7Gvda2xkdXzUOy+LmvVRHyexF0v J2h+o7N7AFRSwqpvrvKDftGGv8fHkLEjAFKaUIVpzK9Tqc2RfCe1vAY3i/WH2BTnfMF3rY sPslrTRpw469ilZ/UcrNLg8HqDkPVNQ= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Skms378B; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id B542C43D69; Fri, 27 Mar 2026 13:46:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF860C19423; Fri, 27 Mar 2026 13:46:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774619211; bh=89JE0t0W4FzLVyP23bqYBnuh2CwNsQQKIZIl2xYaLfE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Skms378BzmiA/D6UoHZMqFCDd/CdHEEeQBcQchaLRjwdim+s1GgnWl+5JBVLnpAMm cbKPDmx9DTssIsoBKVJeAC7+kNgElYmmVK7JgRDodZkwSptrE86un0zAtc0bTn6jOc vcaZ98vrotoVY3/Zl0SAML8PJUSqBwzszdZ5kRSvUf6dBPVT8n6TUUG2IB6BYpVc5S B5wEhPs1jJHndVr/z3zFczH1US1IiU1N49vPmISYYMajrebZEUy/9IdXqOWnrdvy7x aLXGcR/Jc+/laB6lvrpF6TKPPOYQPc154t7HIr7SI+Ewc4XgEgCOwUu/9QnAztP6AY YAv8isoHSvaOA== Message-ID: <10748785-08a9-41c7-bacd-88f05fdf1a88@kernel.org> Date: Fri, 27 Mar 2026 14:46:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 00/10] Remove READ_ONLY_THP_FOR_FS Kconfig To: Zi Yan , "Matthew Wilcox (Oracle)" , Song Liu Cc: Chris Mason , David Sterba , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org References: <20260327014255.2058916-1-ziy@nvidia.com> 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: <20260327014255.2058916-1-ziy@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D4A3D80014 X-Stat-Signature: azfur9e8cdihydih6dj8crakutnr7m1p X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1774619212-517873 X-HE-Meta: U2FsdGVkX18xECD3cZ+xz7g+sKIEg+AjxNHYFxKa1Bmxj6txb6H0TL1ASH4rdIk9RwevVM6V/IZeovRzFNE4eczzxxTt5xeD4t1WzOF2a+QhDnZPccUJJ5V2ahvgal4zO/LurTSo3lZOsbHL9uSZCynyFPCbkddH25LoOZcH0pxU6IYqeDew0yS3rTbqMfpjMpRubByoyA/S7m59d+QO50oqgmYeIl6zJsVfSdq6WXTGBJ5V4lzI4cogx9SeXYxEKWrg4D1nALhbIXHRAMNQcWwd8SJdVEXf9WqWecx0EZ+XRMN0WGPTa7Ikui5XbVwM6vCmGCRs7P+IMq7+CsWnHvsBmc5x5j4kZx+IKeW8YOLXD/kjNRmHtzlQ1VA5T8hMhqZt+9WCnPXLaZ+pfGWlmjAAi9weU4ptQFMHBoQN0160GJlnGKgQXWaeajcQZbLPE9IZiLFXZQ/2GJBMnvXrXD/EXbCPFCh7auxEFlLWK4uAuGUowDo5H5rWp5WwQlby3CKanH4XNGeFef5E8B11be3c7N5Nd5BvjjIH4LjWTxqL0DgEP/ayYKuWOCGGqa9IAV3TCTWjx8lOBopVsobnbEoZ1zX3WJ2yUKw9gm8uNUmn2+y85JVmLTYtTgFy+S0XdH23AFKdgpmJcBzSS5+frQ04NTFil77bv8UaBStjIC4bDrMiA+h5CnCnsG1GEA5aMVtHKJUPFDLOxnyzWna4hBbesJEPJQUX4XMVdC5DR1LfVW2ZfLU8tzqvGS8//q6lH/P99+Pu17FiQVrxVfkY+FzKDm8ac77qlnCop9wqLedfw3O5xWw6szR3bCvdc04Muw7rqy2fHoGIGtfHOOTyEyrLvzBgq7M1AMhyWkE3azqeOrgrX/s221rblr9SwF1PcOFrJ2vsLx0wskDGEErl1U14j3P9bGHpdKA3ZXTZGK5hhmIyYsFjYyJWrNlh0ZNBdWV8d2c+R3l1cvcfJnl ZGTM0gos HdcngMlH/PwHzCE9QykIo+Wyk5CZFqPeq5N4/EvThSMrDcNH62ccaq2wW31yoR4M6eIHayZBxi3IRZ5e7h88/MtQ7PEc63ML2qax4/NyX3jaBr9bxngB/80lLIrOgPD1c/tNJFCwyP4esmf8Fx6hULckkS2lNZWOaoFH55d+WhlRwNRlqGbjQMJ4w4Kfni8d/hd0tPXJYeMo3wKgz/VEpuXsll/VSn1DM1H5mPgfc7kkUsPMFal+qZWRVuZHVtP56n2zogrjXx23h1OA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/27/26 02:42, Zi Yan wrote: > Hi all, > > This patchset removes READ_ONLY_THP_FOR_FS Kconfig and enables creating > read-only THPs for FSes with large folio support (the supported orders > need to include PMD_ORDER) by default. > > The changes are: > 1. collapse_file() from mm/khugepaged.c, instead of checking > CONFIG_READ_ONLY_THP_FOR_FS, makes sure the mapping_max_folio_order() > of struct address_space of the file is at least PMD_ORDER. > 2. file_thp_enabled() also checks mapping_max_folio_order() instead. > 3. truncate_inode_partial_folio() calls folio_split() directly instead > of the removed try_folio_split_to_order(), since large folios can > only show up on a FS with large folio support. > 4. nr_thps is removed from struct address_space, since it is no longer > needed to drop all read-only THPs from a FS without large folio > support when the fd becomes writable. Its related filemap_nr_thps*() > are removed too. > 5. folio_check_splittable() no longer checks READ_ONLY_THP_FOR_FS. > 6. Updated comments in various places. > > Changelog > === > From RFC[1]: > 1. instead of removing READ_ONLY_THP_FOR_FS function entirely, turn it > on by default for all FSes with large folio support and the supported > orders includes PMD_ORDER. > > Suggestions and comments are welcome. Hi! :) The patch set might be better structured by 1) Teaching code paths to not only respect READ_ONLY_THP_FOR_FS but also filesystems with large folios. At that point, READ_ONLY_THP_FOR_FS would have no effect. 2) Removing READ_ONLY_THP_FOR_FS along with all the old cruft that is no longer required MADV_COLLAPSE will keep working the whole time. -- Cheers, David