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]) by smtp.lore.kernel.org (Postfix) with ESMTP id B540AC3ABB2 for ; Fri, 30 May 2025 08:04:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3E0D06B0085; Fri, 30 May 2025 04:04:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3B8836B0088; Fri, 30 May 2025 04:04:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2F5B96B0089; Fri, 30 May 2025 04:04:21 -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 1803A6B0085 for ; Fri, 30 May 2025 04:04:21 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 7B906E0ABF for ; 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s=arc-20220608; d=hostedemail.com; t=1748592258; a=rsa-sha256; cv=none; b=u0UlApK/wKNv02iIYAyp6H9sICIXJEyPszY/7vfYJpU7cYDTHfatVXpgvgc+cFF47mtXwX yt+r1MdZwhWTLsMh0l6QiXnZ/QILMXFg9vGNQR/L2H+Unj8KQ/MmJLMoEf/wl9c8tmTOIb 4rJcADWyj9/p8V3JC+a2aLe8sijmiUI= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf06.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F33FF16F8; Fri, 30 May 2025 01:04:00 -0700 (PDT) Received: from [10.57.95.14] (unknown [10.57.95.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BFFC83F694; Fri, 30 May 2025 01:04:14 -0700 (PDT) Message-ID: <05d60e72-3113-41f0-b81f-225397f06c81@arm.com> Date: Fri, 30 May 2025 09:04:12 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] fix MADV_COLLAPSE issue if THP settings are disabled Content-Language: en-GB To: Baolin Wang , akpm@linux-foundation.org, hughd@google.com, david@redhat.com Cc: lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, dev.jain@arm.com, ziy@nvidia.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 894FF180006 X-Stat-Signature: fckz8x9orowjgtaduus415facsgte44h X-Rspam-User: X-HE-Tag: 1748592258-211478 X-HE-Meta: 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 hCZoAEIy KDkvKh18gH6AVfudoXIUpgHODem0XXfa3ix7VT+E6tAjCeAd2oFSYC3+ZtfG2YvSd92w78yTC+u2UfeNiMi5Q3aNBBINMT6M6Pj2GhC9nt4lUBQhdbvvPAnhPibMwHbFiEC8xy8rAfbd/G6hkS+YZpSl/r1NfBcfXB6DItD7nniDbu86x5mXdKGu3/bQS50HCOggY0gqIqK/G37AsMDd1axisFZA0x2Kl098c+bo3xVPoOCg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 29/05/2025 09:23, Baolin Wang wrote: > As we discussed in the previous thread [1], the MADV_COLLAPSE will ignore > the system-wide anon/shmem THP sysfs settings, which means that even though > we have disabled the anon/shmem THP configuration, MADV_COLLAPSE will still > attempt to collapse into a anon/shmem THP. This violates the rule we have > agreed upon: never means never. This patch set will address this issue. This is a drive-by comment from me without having the previous context, but... Surely MADV_COLLAPSE *should* ignore the THP sysfs settings? It's a deliberate user-initiated, synchonous request to use huge pages for a range of memory. There is nothing *transparent* about it, it just happens to be implemented using the same logic that THP uses. I always thought this was a deliberate design decision. Thanks, Ryan > > [1] https://lore.kernel.org/all/1f00fdc3-a3a3-464b-8565-4c1b23d34f8d@linux.alibaba.com/ > > Baolin Wang (2): > mm: huge_memory: disallow hugepages if the system-wide THP sysfs > settings are disabled > mm: shmem: disallow hugepages if the system-wide shmem THP sysfs > settings are disabled > > include/linux/huge_mm.h | 23 +++++++++++++++++++---- > mm/huge_memory.c | 2 +- > mm/shmem.c | 12 ++++++------ > 3 files changed, 26 insertions(+), 11 deletions(-) >