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 13C82108B8FF for ; Sat, 21 Mar 2026 04:04:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 230AB6B0005; Sat, 21 Mar 2026 00:04:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1E0FA6B0088; Sat, 21 Mar 2026 00:04:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0CFCD6B0089; Sat, 21 Mar 2026 00:04:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id EE9AF6B0005 for ; Sat, 21 Mar 2026 00:04:56 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 71A0313A7FC for ; Sat, 21 Mar 2026 04:04:56 +0000 (UTC) X-FDA: 84568729392.19.1E95E6C Received: from mail-pl1-f181.google.com (mail-pl1-f181.google.com [209.85.214.181]) by imf07.hostedemail.com (Postfix) with ESMTP id A63914000B for ; Sat, 21 Mar 2026 04:04:54 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=google.com header.s=20251104 header.b=vrHObXMu; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf07.hostedemail.com: domain of bingjiao@google.com designates 209.85.214.181 as permitted sender) smtp.mailfrom=bingjiao@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774065894; 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=Vb0hgyyRQxiEoRD57QPoNnifO28j8YAw05wFPmEsgvQ=; b=NWNG4sGeud0p7xCsdx6GZnVkbuccXvKraKU7Vqj4N1lOscNnSPc79gn+jJ6hqNmdA7Pfrs Qe1TiKdsIVS3H2TBsNmvmNTc+u2CbopWE0JDL93lzBjILgfyl/K5sgX+dalu70DEF6E3Ok kFP12bM8aq95hM5N9ZBkVEt7RvGIa+U= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=google.com header.s=20251104 header.b=vrHObXMu; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf07.hostedemail.com: domain of bingjiao@google.com designates 209.85.214.181 as permitted sender) smtp.mailfrom=bingjiao@google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774065894; a=rsa-sha256; cv=none; b=BqOk5LjA6MRCYl7wlxryHWfWSm60od6Jqrw+px0WlR6V13X3y6LMPL4oNFC7nIgRxrai0v NtuhAPngtqD/0VhYEtt/p6Mtld0P1aTEc5t0cXChDTZASR9XWuVKYYq3D6++QOuqqLWrDr QnF8E6Jt1T5u6UFAkKdGgX+lgyDSj8c= Received: by mail-pl1-f181.google.com with SMTP id d9443c01a7336-2b052562254so55695ad.0 for ; Fri, 20 Mar 2026 21:04:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1774065893; x=1774670693; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=Vb0hgyyRQxiEoRD57QPoNnifO28j8YAw05wFPmEsgvQ=; b=vrHObXMu+HvaAIvCI3GLaMTqS6g9VBnQ+WJ+QSAH7CMfx1Rjdf9UIR6MyAUn72NxsB SuKMbe2Hnq+V/o1UC7C6T5ZsauHMV80ss0HaVQTKHyBoPtT6LKZCXTi6AsbBhgRyLdD/ +nKSjEURqPs83WxPGD9gBxKwpso3WLrqaTEdvwWaRqI3f1EDj7OYrJqRXfmxk4wU1Qyy 46MEewMJefQ6Pr68tVTt91M2henmD1GWqYlSX0pKLZvO9V+TRHdJ6kYbaE7ZydvzRGvS zM6XhX1y4JPxT4W+8sSomGqdNIU1pRHczZqyC4e+0evWB1ShW1s+VlY+r/9bFht66Bl3 6hVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774065893; x=1774670693; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Vb0hgyyRQxiEoRD57QPoNnifO28j8YAw05wFPmEsgvQ=; b=jbQmc4o3QyhgU2dVtXIS+zA++OHplHtgh1Pn66rM2nCRzKoegZwhJFSG7ktlEeF5MW eTzl5PO2qEmGf1XYOWliWFEfDJDdAgRRP60rfGHP8dGCDmkpDGuiIwp3edVA23j6xL+M Qn3bkTd3e3v5Ihiyf/jNK2GUu/gju3gsqEzEHxegJibuBljx5/KgSf/5QXjtiPj+CJZX 80YGiL+ONPs+w/wRkdl6Cb0Dc+rBrEXMr0WfkoSLQaTJiaJ+edA11FTKqfhA5wOHOJWO vmklcOgk8N6LqegOnlYs6L8OoE7scPN4DDwtiRnrTz5jG7CY+ts1KMLpVn2QX5Y29zzA cIfQ== X-Gm-Message-State: AOJu0Ywudg9zcCq0c5S2rhbKQIMPPQsMYvWTbdRdNna4n0g4U1W3gdvp 0pqVR59nhJ6HAKmfzs05Mtd8apUWpIa8FvmmRqKhwCOYIu2sZhnZbEVWpt0k9UOE5A== X-Gm-Gg: ATEYQzycy42uw5TLKAMULf+GtkV8SoyA7HDbkYas+9IH8ZYpHvVRr2o4d1HKAXLawJa 6WcetQ+WW5Tuj9AaFtMtZDgj1Rw8sGxhMLLDSMWjhli+TZRZTE+u6DsQ1BpFi1Rm6NFB6ecZIkI sfsABueKWkdWgQXBoO+GzLM48K3gPNMviTCttXqTM1vWxglevf8HLTWeH0HksqKeU/V9qy2dbV1 TzyrQC9pXsbv20rNq5H/REDLpQrhwGssvda6OlB+zc4Hk625xlfrm1K5weHf9I8W7Hi6r/1+Ea1 +gXpNvSz4gWnVF6Atn6n7HgoOx7A1tJXx1Z0lxYaZQe98CMRFE6FHJ8twTX7VWaPYj2ckg+dyJa 1yhLCqHnGe1Tsa9d7zu6ys1qUzqqqGzIBeluDHAZa8g+g/JV6G8OZozjWE8tY6udRQoxpJWheFE 0w6TRF2SfBsKOyV/vZL1mGG3Ph4i9zmcgKA7vofQSaM3hdwkWw0NnGq3eDI1Z5OdkN X-Received: by 2002:a17:902:ebc5:b0:2ae:7fa2:6bda with SMTP id d9443c01a7336-2b08c38a9b3mr1002905ad.1.1774065892911; Fri, 20 Mar 2026 21:04:52 -0700 (PDT) Received: from google.com (206.238.125.34.bc.googleusercontent.com. [34.125.238.206]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82b0409f582sm3411460b3a.33.2026.03.20.21.04.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Mar 2026 21:04:52 -0700 (PDT) Date: Sat, 21 Mar 2026 04:04:47 +0000 From: Bing Jiao To: Donet Tom Cc: linux-mm@kvack.org, Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , David Rientjes , Yosry Ahmed , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , David Hildenbrand , Qi Zheng , Lorenzo Stoakes , Axel Rasmussen , Yuanchu Xie , Wei Xu , Joshua Hahn Subject: Re: [PATCH 2/3] mm/memcontrol: disable demotion in memcg direct reclaim Message-ID: References: <20260317230720.990329-1-bingjiao@google.com> <20260317230720.990329-3-bingjiao@google.com> <380c52cb-fc8d-4fbe-8d2a-f153bd179816@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <380c52cb-fc8d-4fbe-8d2a-f153bd179816@linux.ibm.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: A63914000B X-Stat-Signature: pyenboew55yc9adbaqarjzxayhbubwkm X-Rspam-User: X-HE-Tag: 1774065894-560516 X-HE-Meta: U2FsdGVkX19Yc0CXukHpAY0Fs67gFSh90UejPANXR0GBlSIzWrc4i3IzQIifQnVqjQ4u6o3juEkTUPuyzUYvo8h1bap8iBoqa1kMzwjRg7Cmd+I0YtHZjp9j14n23I8cnFXDminE3aCWHVH+ja1/oHvqQLhkjjdNO9FNHbnaHjB6pmVFP9qDyQkAtPFAF7lsp2g+LcBb4wORmRW03gWWjdfCBf+E4r/1TRwhUup4w8US3QS9XEQDTSMKiPqWRgvd2f+JkmLdJS1bKUorXd5N7wVRj6OmXCL9uOlHO0AbFI9Yg86/+7f2GfXJgjJFX7epNr1ACqftUTDN9DyvLaO0hbHba3ij/T4/wg6cwYFNWG7kY8elEA8UEAUFD1OJsXv6JplWMv45BB/Dw5cLG1SnynBXxoFbfnf0Dm+MYvLwD4ng/MBD8qZFGYyTvkJCBN+xL6ugA6zLq2JpPMPBo2I1oNxROEHyaF1Eq9e0T+sLuriF1JMpErTotIZD5qJ0A9iv3zGnIA6W8ywZ6KLkFkj5KiGi0QO246n/4CilOPgN0XF+RbO4OWWr/ZUkpNDnqmnJNuB+9iDVwy6sB6c5XfruSldZY6HmG0pNhDPHefVKKq820ia+dHDfBgpH3jaLgCE6iW5ZDRTZO6COTHaDd0Gp/o90BLtf9CbjWOmxruC7fm/UgXPcm2boGyuQMC1Z5CDdF9wJ9QZnVqPjJkYanIdwYeoPQTQiMz4VGDr8E/CnCihuOa6fiSquXtUyVPuKMkAfp2TCS7BDzj13GJNhFKkTc82AwrXDzawlUWnt/KPTMPEkX56uPoZKIrPnoF3y9wnL66LXuEpu/RrfDqdQbf28c6Jo1xkZ5HO07KGRzncHWNQndVEdJzuDfY9Nqa74DiFJj8rZQXLfjNVteRkEuSw7tmW9TzbZZzNAuZnZp4zpCnm3BdEYNzjERaKVSMoXvLN37tPCBkWBBweXL01JyhP /0AYhuK4 phw85A2J/WoT4slWGoh1YcBmj3qTozLaiuHf7lXV8DoTmZ5aS6UIVvp8YhLBhRRJKxufkHBtLM9NC7Zs7wXH6Q3DcRrM8AH7t9Y0Ic7Hv251nAaCjA9tSwjFmkEoR9ZdtpT9DZBgCxuonAVju6+dwKhTVOy3ooUFVdez7KcKWM3JCMMZ77fpnO+/DZmUgTXc/e5CuPiCtkMp6KhkPCzAWlY3YhJ4q+YZOaTqSYC+pOh57nWknu+aog8AKzEI1RdjWADRo+ovJurj/De2MUi75v7uRvkHDFtjJUHebVfexM0eY3edtBm5ZmdyLyFXhV0OpJJ6dvs3m8yqtIDYE8cEBX+rNlaux9EuN7jMXb/WSNGqqKkvb1Ea+m0I2uWmfMaujv9VS+ShGU7mhBwzbatrDIcOhDY+KpV099P/xgV+3dYv4jh+rFWhB4oTyooH/iTggVY2YsEJsl/0AduT3J0eXx45addggRExj8TgQIBjZzwtMD8paMZ8uJqMzXg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Mar 20, 2026 at 06:47:14PM +0530, Donet Tom wrote: > Hi Bing > > On 3/18/26 4:37 AM, Bing Jiao wrote: > > NUMA demotion counts towards reclaim targets in shrink_folio_list(), but > > it does not reduce the total memory usage of a memcg. In memcg direct > > reclaim paths (e.g., charge-triggered or manual limit writes), where > > demotion is allowed, this leads to "fake progress" where the reclaim > > loop concludes it has satisfied the memory request without actually > > reducing the cgroup's charge. > > > > This could result in inefficient reclaim loops, CPU waste, moving all > > pages to far-tier nodes, and potentially premature OOM kills when the > > cgroup is under memory pressure but demotion is still possible. > > > > Introduce the MEMCG_RECLAIM_NO_DEMOTION flag to disable demotion in > > these memcg-specific reclaim paths. This ensures that reclaim > > progress is only counted when memory is actually freed or swapped out. Hi, Donet, Thank you for the feedback and reviewing the patch. > Thanks for the patch. With this change, are we completely disabling memory > tiering in memcg? Yes, this change will completely disable demotion from memcg directly reclaim, as demotion does not help to reduce memory usage. > > Did you run any performance benchmarks with this patch? > > > This patch looks good to me. Feel free to add > > Reviewed by: Donet Tom Thanks again for the review! Following a discussion with Yosry regarding demotion as an aging process, I have decided to drop patches 2 and 3 from this series for now. Additionally, Joshua Hahn's RFC ('Make memcg limits tier-aware') [1] introduces a mechanism to scale memcg limits based on the ratio of top-tier to total memory. This approach or similar approaches might provide a more comprehensive way to resolve 'fake progress' in memcg direct reclaim or establish a better framework for addressing such issues in the future. Hope you have great weekend! Best regards, Bing [1] https://lore.kernel.org/linux-mm/20260223223830.586018-1-joshua.hahnjy@gmail.com/