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 3C05EFA0C5E for ; Wed, 15 Apr 2026 09:22:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A8BDD6B0098; Wed, 15 Apr 2026 05:22:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A63226B0099; Wed, 15 Apr 2026 05:22:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9A40E6B009B; Wed, 15 Apr 2026 05:22:07 -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 882526B0098 for ; Wed, 15 Apr 2026 05:22:07 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 2FB1CE3615 for ; Wed, 15 Apr 2026 09:22:07 +0000 (UTC) X-FDA: 84660248694.18.20B58EB Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) by imf29.hostedemail.com (Postfix) with ESMTP id 4CB48120005 for ; Wed, 15 Apr 2026 09:22:02 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b="Uin66/hi"; spf=pass (imf29.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.119 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776244924; 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=k50XcOiZunNGbhAMmY/+OGWwibmB7NY3ZE/wH+AVnkA=; b=QG5BXZl+8ugkdXm0q9m503U1u6hbYuV2WX95oWbHHX4c962+JA7+VPgwyYj3TrSX8dxRiL 81hJYNSuwbk4QQdIwT2DoAMhDPGe9C+LPLTJOdaxUyIg3z3ffPk7wRaRVlobMqjIlLx4I1 vfAmSA/j0zxX0oJbZYTytcAFHBZicnU= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b="Uin66/hi"; spf=pass (imf29.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.119 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=1776244924; a=rsa-sha256; cv=none; b=PsgwoOITUo0PlVRm+hXHVmgsaA3prQCCY3EJGWr5Zc4VBontEOkSLGbmRmu14Vw3R45pwF tnR+q22Nila16sCOaAGrfgBEO/Ny4A2aHIi0N1GIiuldAM6RnQ4TK9TEFKSSCXoQ0jhu1i MRpIsFWUs0OHy5musLZqDO49FdfU6pg= DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1776244920; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=k50XcOiZunNGbhAMmY/+OGWwibmB7NY3ZE/wH+AVnkA=; b=Uin66/hiT2zzpcmdZxjJ2BPXErJ3vlB+h1UHc1YFsxig+tr6idfi9WU8ST5rz3ZHTgzhKsamisSbEAfitpPgAvHV8EeNPZ4BpY8EBU1j/3O881X/slJdJKY+v0Uhxwr9CG1H1u0jh+YRLQWXs6R2u4G3qXe001EnICB9+phKCew= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R571e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033032089153;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=27;SR=0;TI=SMTPD_---0X14F.Ps_1776244917; Received: from 30.74.144.121(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X14F.Ps_1776244917 cluster:ay36) by smtp.aliyun-inc.com; Wed, 15 Apr 2026 17:21:58 +0800 Message-ID: <38697379-cbba-4c64-ae65-6774b01021d9@linux.alibaba.com> Date: Wed, 15 Apr 2026 17:21:57 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 7.2 v2 05/12] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check in hugepage_pmd_enabled() To: "David Hildenbrand (Arm)" , Zi Yan Cc: Matthew Wilcox , Nico Pache , Song Liu , Chris Mason , David Sterba , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , 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: <20260413192030.3275825-1-ziy@nvidia.com> <20260413192030.3275825-6-ziy@nvidia.com> <05F00072-7E06-47C9-BC26-FE3736F557FC@nvidia.com> <84B8F641-A3DF-4219-AA57-6BA48E9B4998@nvidia.com> <998c02b6-2612-42c1-8099-d65ae275d1a2@kernel.org> <7468C68E-FB09-4714-94A3-4BED63453295@nvidia.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 4CB48120005 X-Stat-Signature: cgpka6m387djnsfsix8n1mkp4p7o1s5x X-Rspam-User: X-HE-Tag: 1776244922-165064 X-HE-Meta: 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 f5pr3C8D cGoI4hT92/Sf72oqUxwi/JtVWc0CDdGJ5ecsvpXrYZImQu667b4RFjmraRDF8mClOdqdOU2uaoIzSbvrZHMiAgWxuVw4jjmWh5Ar+GRpZLeSqq7hb/g40dlMv2NqsATf3Nq9i0PHGyz1Cjwq//Xge/Jl2JwN+N8fUOEmMzOuFG8GjU6BPABkW/kYzSlmmHVP6GZqEyB2Z50olwMn1iiwy5TcT9xD3n6x65lwYIXwLpl7ZV8cS6G2SR86jcy39fyrg0dB9xngRfC4RH9q446NPA40Uo1Tqb+2UiTPOrnV9lny+WXYXJ/3bCNn+el78efGjaQdC3sozkIUjSJ+RrYMB7466I6SHStCXR78M8+MbwQHTGoO2zf6E6jzIkFXH70j6Rt1m Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/15/26 4:00 PM, David Hildenbrand (Arm) wrote: > On 4/15/26 08:36, Baolin Wang wrote: >> >> >> On 4/15/26 2:25 AM, Zi Yan wrote: >>> On 14 Apr 2026, at 14:14, David Hildenbrand (Arm) wrote: >>> >>>> >>>> Yeah, it would be better if we could avoid it. But the dependency on the >>>> global toggle as it is today is a bit weird. >>>> >>>> >>>> I don't think there is other interaction with FS and the global toggle >>>> besides this and the one you are adjusting, right? >>>> >> >> I'm afraid not. Please also consider the per-size mTHP interfaces. It's >> possible that hugepage_global_enabled() returns false, but >> hugepages-2048kB/enabled is set to "always", which would still allow >> khugepaged to collapse folios. My comments are in reply to Zi’s comment: "I think hugepage_global_enabled() should be enough to decide whether khugepaged should run or not. " I’m concerned that only relying on hugepage_global_enabled() to decide whether khugepaged should run would cause a regression for anonymous and shmem memory collapse, as it ignores per-size mTHP configuration. > The question is really which semantics we want. > > Right now, there is no way to disable khugepaged for anon pages, to just > get them during page faults. Right. > And we are now talking about the same problem for FS: to only get them > during page faults (like we did so far without CONFIG_READ_ONLY_THP_FOR_FS). OK. I’m fine with using hugepage_global_enabled() to determine whether khugepaged scans file folios. My concern is that for anonymous memory and shmem, the per-size mTHP settings should be considered.