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 9D329F483F8 for ; Mon, 23 Mar 2026 21:21:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CF1166B0089; Mon, 23 Mar 2026 17:21:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CC8946B008A; Mon, 23 Mar 2026 17:21:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BDF5B6B008C; Mon, 23 Mar 2026 17:21:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id AB6646B0089 for ; Mon, 23 Mar 2026 17:21:41 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 5BAD413C200 for ; Mon, 23 Mar 2026 21:21:41 +0000 (UTC) X-FDA: 84578599602.06.6BE8910 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf28.hostedemail.com (Postfix) with ESMTP id 7B0E1C0008 for ; Mon, 23 Mar 2026 21:21:39 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="A/FYPNYh"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774300899; a=rsa-sha256; cv=none; b=lswrIA3khvtmPwfEDtqofre3pb+IfTLU2KXB1IhBwxYL9tXhURy8hsjrFAVKLYBf4tBYf0 97vFZMuIaEw2U91kFP2wC2rBCumv2dFi4Xo4TJhDEr/EDkcXcffwHo5oaPz52dOVdaBcyS NzhNjRQrI11JaATkLdoQp7Lq6qzua5k= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="A/FYPNYh"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.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=1774300899; 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=E0HEUk1oPQMtCkKsk6maK97UsbKzlpyP+CD/kjWayS8=; b=eP5688gQ4vT1vuELEavpfY6p6F1LfJvMPrhpTO53qM1QJWj+7lJzFEco3obj722Qeyr/MO HhdQjk2eEWn3sR+02fbK2VBQ2+sZyOnJVvHPsSp55PXGXYz/8pQaaL9qpIbXGC2lLb0fKY Nj+HQM0g+y51z2sE9NKbMPRKCfyrteA= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 87445443F1; Mon, 23 Mar 2026 21:21:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1BD2CC4CEF7; Mon, 23 Mar 2026 21:21:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774300898; bh=04FQMew05zNRTl9YF6JQB/WHdSB2fffkG+BUPcscUw4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=A/FYPNYhals6ENz1Ox2wRKyW9TL57KAfLjRpKUc/1hHqneXx0woVnhJQ7WEh19lx6 qxlatf7Ms1tUHtE9lNj3isEMDDKvfQZ8LjCyU47szC0BcPLqeIT5hkITD4ULoD+bo5 71zRtTumPiy1HOGFmwRdgH1rb+yai+RQKG/ef28/E5BFqFGiT4M/bysdG1JQRZcpN3 PxEs5sVkCbpgYNaH5hDVE33A4R7Xr1wMfVNDPDUis3mQUYxZV5Tf/LakCXxm/uwIhL 3J4ZrtKZiychGsj05yrepRmZdamPxG9AnKtI/lvIOPxIjXdnaqFSP0daKzJAYW0U8n NiBciLy4xmCWQ== Message-ID: <16117b49-d83d-4ceb-b85d-d117d6993ce1@kernel.org> Date: Mon, 23 Mar 2026 22:21:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 02/11] mm/khugepaged: remove READ_ONLY_THP_FOR_FS code in collapse_file() To: Zi Yan Cc: Matthew Wilcox , Song Liu , 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: <20260323190644.1714379-1-ziy@nvidia.com> <20260323190644.1714379-3-ziy@nvidia.com> <7382046f-7c58-4a3e-ab34-b2704355b7d5@kernel.org> <71148f2e-cceb-418e-b762-c8dbd7a7eb1f@kernel.org> <9648838a-ada7-4983-99e3-d694e803e06b@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 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 7B0E1C0008 X-Stat-Signature: moo86b37cn4b9mkz3atf6yi7s4qqsgis X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1774300899-735543 X-HE-Meta: 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 H0xhBrfi w1apzcKfoa7LR1ScAFP+oW+CdpsecOhkZrNXZFsneZ3Wki9HX4pO6kkHT9J59EISYEOI7A18lXbix6+jVtTlob4GDte4mHxGxP1nnVoXvpJJRZvhfQ66wXXaSm2+z/gUyks8GjJZ+Xu4TIEmYhy82LqrK34PReAxkr4GgCr4AVUPNzwJzx1rhWTKMux554qT3bm0K/EDV7QQrNT6bnsllTAVNltPz7cX5TXEj7wv5j50PRgn7pzHcJBw9QvzNsRqjD+yLtcriLb9aV0410i2gBm0Z5j20gio43fRv Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/23/26 22:11, Zi Yan wrote: > On 23 Mar 2026, at 17:05, David Hildenbrand (Arm) wrote: > >> On 3/23/26 22:02, Matthew Wilcox wrote: >>> >>> Not necessarily that lucky; if you set VM_HUGEPAGE, >>> do_sync_mmap_readahead() will allocate PMD-sized folios automatically. >>> On busy database servers (and is there any other kind?), khugepaged >>> takes too long to run and find opportunities to collapse text pages. >>> Like, days. >> >> Yes, in particular given that the default khugepaged settings are awful. >> >>> >>> >>> I think the test needs to be: >>> >>> if (mapping_max_folio_order(mapping) >= PMD_ORDER) > > This is very helpful, since I was thinking about using > mapping_large_folio_support(). > >>> >>> as there can be cases of filesystems which support up to, say, 64KiB, >>> but not all the way up to 2MiB. I disapprove of this situation, but >>> this is where we are right now. >> >> Right, that's what I had in mind. > > Does Nico’s mTHP support for khugepaged include changes to collapse_file()? > That might change the above test. At least not regarding adding support for other folio sizes. Baolin (IIRC) had a version for shmem support, but that will come after Nico's series was merged. -- Cheers, David