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 9F9EEF54AAF for ; Tue, 24 Mar 2026 13:15:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B88C36B0005; Tue, 24 Mar 2026 09:15:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B12CB6B0088; Tue, 24 Mar 2026 09:15:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A01926B0089; Tue, 24 Mar 2026 09:15:57 -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 8F5DC6B0005 for ; Tue, 24 Mar 2026 09:15:57 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 44E41161C10 for ; Tue, 24 Mar 2026 13:15:57 +0000 (UTC) X-FDA: 84581004354.13.CFACBFA Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) by imf19.hostedemail.com (Postfix) with ESMTP id C4D421A0011 for ; Tue, 24 Mar 2026 13:15:52 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=lCLEI5rn; spf=pass (imf19.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.133 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=lCLEI5rn; spf=pass (imf19.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.133 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774358154; a=rsa-sha256; cv=none; b=mrdxqzBdWsrauOBOF0oX/uoNyGxOvZswCepxPO4B86pJ3/++Df0lW7nCWc3t6mx4tCBeZu 6MJHK+dNOa1KE8q7cQofhOCmEErZ+EhKlHcg/K5xl6iXPb0jA0qqzeWf8/DE+ZvVRHwS4V 8adovcBrz6lPdvbUUt6n2//3oIRl53M= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774358154; 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=/gTgQCP+5YBhbolPTDqqpYhG/7AEExmRx0uocLkbImg=; b=RYQw3f0ntjvsbFhv+y/4x5QGj/EV+TDIEq4yMFuXjS3t6IsahWocVZLIhkv64a5OwY49PM pV5l8Eju+SwKhe4NtR4zaW/42gizpiVVYX5IhZZoKq8cKpL7pYRQQP3gVg63cUTEK5cRUq y8EDHfXv5Rl7xGQ2chftvfghH62S70U= DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1774358149; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=/gTgQCP+5YBhbolPTDqqpYhG/7AEExmRx0uocLkbImg=; b=lCLEI5rnVCaGOatpQquuNr+NQzvHK+dxa0bWVOJQswXydAKL0FBWb32iFbukUTSHlxrFf/caIPltXXNajKU8V5OucvR6p4i7ziVY+vD803W6VxgAmC120+kcT70AAg2gmfpoLBlWKxOCONTSrMS/rNC03yBpuGmM1rA5e1fJ9Mg= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R941e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033045098064;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=27;SR=0;TI=SMTPD_---0X.ehy5D_1774358147; Received: from 30.42.98.36(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X.ehy5D_1774358147 cluster:ay36) by smtp.aliyun-inc.com; Tue, 24 Mar 2026 21:15:48 +0800 Message-ID: <33f09051-b5a2-4f40-8ea8-a7cade5019bf@linux.alibaba.com> Date: Tue, 24 Mar 2026 21:15:47 +0800 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 , "David Hildenbrand (Arm)" Cc: Matthew Wilcox , Song Liu , Chris Mason , David Sterba , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Lorenzo Stoakes , "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> <16117b49-d83d-4ceb-b85d-d117d6993ce1@kernel.org> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C4D421A0011 X-Stat-Signature: 9exm8p6ico17aqxhqo9trtxkdbcs5d3i X-Rspam-User: X-HE-Tag: 1774358152-203292 X-HE-Meta: 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 3KVNxWHZ 1OpLsAHvMKWpZQSr+eBFckavqFDCKyVuIAAkLKDQtuyzUfjZy+6QHG3+szGMYsxLYrpO8SsbYszJTG/1O6F0Fafy6CimtpxG27iywCvbgz3DGdRwzCkQGwJXlcxhSFRnlfsP/tSSBP1GrsPo6bR5ks/OjQHCMS0C/YX9vnEfBj6MbvLkfrDkC/D6XST8h4RLu9hyrGbqs4WB7geA9mVTF/rVgJDTiQRGFcpPiwX3zXT6nib44HJLymNZrpdngMxB3JqwG/Wp4HfIlm4IJ3KpcnGa1RpCgQfqsvs9CiUMXCtc5PlIKYBWzOdlQE1OkhvnOTYt2m3LznYjI8BPLehXSlAkiWWqoDct9+iXetZ0adYOgA8o= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/24/26 8:12 AM, Zi Yan wrote: > On 23 Mar 2026, at 17:21, David Hildenbrand (Arm) wrote: > >> 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. Right. Here is the link to the RFC version: https://lore.kernel.org/all/cover.1755677674.git.baolin.wang@linux.alibaba.com/ Moreover, I have further updated my local tree based on Nico's series. I will send out the new version once his series is merged.