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 7C7AAE9DE68 for ; Thu, 9 Apr 2026 08:27:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C19886B0005; Thu, 9 Apr 2026 04:27:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BF1496B0088; Thu, 9 Apr 2026 04:27:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B2E176B008A; Thu, 9 Apr 2026 04:27:48 -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 A54526B0005 for ; Thu, 9 Apr 2026 04:27:48 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 49AE0160421 for ; Thu, 9 Apr 2026 08:27:48 +0000 (UTC) X-FDA: 84638339016.25.47F99C4 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf07.hostedemail.com (Postfix) with ESMTP id A233640013 for ; Thu, 9 Apr 2026 08:27:46 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=DDjVTAIi; spf=pass (imf07.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775723266; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=XOLbiyFZ6yUTc+lvkxPmguuF+R5YrtfocWqBWRVawTo=; b=bgC/AjEsD/oXGTRStufINqADR/jFxMJlGi1BLilN+XoDdux3BkpZT+BPmWK29I1nK9zqOY sk75GIjcot/kcsYJAK4X5yl71DfyKUMUnEyckukU0MzEAbQFyM4XIc51S2yiab5XxLpgMX dQDifzux+KOtAp2AR/yz2nzNNiLtW68= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=DDjVTAIi; spf=pass (imf07.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775723266; a=rsa-sha256; cv=none; b=TVaastBdnIsQhWzGGoHhmpc4fuDjsjw2nd0Cm1+x3QNON5EbQxkWY4Lj66mjHg7yySk/Gs 25kFOtNs5tpZyv5L7cz79OrtsJL1UjNc7iIHubEZ9N3cb7ynFa8BDUGCVjY0HEG/IoFO+G zVNBbBw+WHtzbdAcEBCh1d7RmaU//qs= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id A0F9140DB9; Thu, 9 Apr 2026 08:27:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55F0AC4CEF7; Thu, 9 Apr 2026 08:27:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775723265; bh=XOLbiyFZ6yUTc+lvkxPmguuF+R5YrtfocWqBWRVawTo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DDjVTAIip4E5V92VROBLPSNEdCRwyYe7VvOXqlsaszBjwomvTUkfdwYa1WVb8oO7a Tzb1od3eGe+AysPGY6/Dv0kx+EQT8nHOWUr2CdAumZOap50cHVsAvhV6g2vE/X2iEC 3AqSDNRKX4otwBgcIh6cVZtLMtB8Qehn+pXh2bXQNVZ+VshbERf9HhuNuQqodsSrFZ AcZWCVEJ8yuJZ0dKUcLrI3MBowViBvmIuFi8U6YN9ghjHFE65x0bSMobAJuQtvA/fk Pjb7TBluBzfgyNVOcASwY3MBDd+EVSLLRp2PvyM+K1D7GvSDdyN3zsVIsd7nh+K8Ok 3hgNqLlysNMtA== Date: Thu, 9 Apr 2026 09:27:40 +0100 From: Lorenzo Stoakes To: Kefeng Wang Cc: Michal Hocko , Andrew Morton , David Hildenbrand , Christian Brauner , Alexander Viro , "Matthew Wilcox (Oracle)" , Jan Kara , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH RFC] fs: drop_caches: introduce per-node drop_caches interface Message-ID: References: <20260409063503.3475420-1-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: A233640013 X-Stat-Signature: rgdxy4gaddgy9uq7hjbnza4843c9k6sh X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1775723266-953364 X-HE-Meta: U2FsdGVkX1+V8vE/N8FSN6PoUcXcpjpt9kj/r5SOvuKFU6pmfE/dedckyS5rycQD9cg35G8uWxfjgCkjwGgTxLdrBQPkWJOpe426L+VQ8YDste5dzvg7qytgc+yrNnA7U5buKBI0aOUf9r3nKaxyylLKY/Bk77gF9f/rLLSNkhN8M3L4dnCy4M4wekmsPxHa2OZI9FnV0WUHmXllAb4c/oCidlLJYaBVPQw7depNnO934gsziZ4JimrVkoVg48Z5o+PYCqrwHT5XxwyfhYCHj8cdUy9SGEl2PZSDy08RI79yP0zYUeGnlaXeU3JPev7w0wCGNLyoHMEZBotx65buQRhBQMybKefG7zba/T7i+UUlKNNqphwCp2vyPSoN/084o4KdiV5YUea05rTjLIW79YMkvW9wRfyNKPI8oz+S2Ejszr+706H0o/MMFNwwSkdRr91DyzF0Fm20fvtQQgs2w8aS/t5iKt3+DBPu2G1Ahst3/r2ZD6CAV/m1JsEhGHe0FGDyUm3TEsoHzvu85kxz3SPPmz98UjzZwL/0AC//KAhX6gWEqGaT9cPPmuEMCSx0z1SBEL+nLKqG/n/p1yjYB/wfBQpO/L9n+yYGWUS5AWTPzOf1xP1FEtuc8aDTkY0FayHdRuoxXk42gRBz/OkCQV5EGjGn1aA7QsxfXPfJJWlV6B9mH+Uc8CmnssotfsqusRASseO+EiqVSgrG6ymttPCwKAT5wAiKrpiqadga6xYyrqT5pRlz+08twaQgSn2ld5YPwpkMR6y5GKeyYqZ0GfMK46gee+S7TuvOSWLkGlJMg0cMQPzkUORGChq1amkOZemiXtjhUBF8AkFiwEPv5nMprBZpf4zanVNjWNraNvLdTr1pJS0/VF4wRnNkrx6V6uAhqC0q7w5S2NfkCq+M8m7OTJrdEitp9qZPrEpq02fNwDaM7yJ+jZszx7cAFNV7abMFiHB+xlYJlt+c6PA z6KoQNbI S07BCD2mC5TkNUAwq9bwIRaoTWzgIXU1tpNfdbkNAybmhzPm91fOL5b1CFVplfrpNegjsG0X2SP5ii7APm6ru2VAPj8GIfRsh92wIxKwnbbHNXdaw+UvylwgMBLq4fQdK9tqjcSAfv1nS47fPNuqY2T0pHU6X9jUwHBcDzCiv0grt/gdWV9BmxALyjTytzpVK0lSU3qu/KCkMm34I/JP7jv8JP8yK1oMImVm/1ov6uU9h3sXqcLE+EY3vkgFmJhyYgTnlUX7Np5bUBa/BOiWhZwQ9+OyTJZBm89+YgHHgAoimlYROnrq9QhQtpsXBYROP42t6alGHGMpBzpQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Apr 09, 2026 at 04:21:43PM +0800, Kefeng Wang wrote: > Our use case is as follows, for hot-pluggable nodes, for anon pages, > migrating them to other nodes, but for pagecaches, just evicting them > since pages could be refaulted. For mem-tiering, a large amount of cold > memory is stored in the low tier, we think that evicting pagecache is > better than migrating them back to high tier, also this avoid the risk > of accessing potentially faulty memory. Hmm, this feels like it should be a heuristic in mm rather than something people are manually triggering by writing to a file? I'm not sure I'm OK with us allowing people to manipulate core mm page cache state for non-debug/synthetic perf analysis reasons. Cheers, Lorenzo