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 9172AF532D0 for ; Tue, 24 Mar 2026 04:25:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D00366B0005; Tue, 24 Mar 2026 00:25:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CB12A6B0089; Tue, 24 Mar 2026 00:25:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BC71E6B008A; Tue, 24 Mar 2026 00:25:43 -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 ADAE26B0005 for ; Tue, 24 Mar 2026 00:25:43 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 501BCC9FC8 for ; Tue, 24 Mar 2026 04:25:43 +0000 (UTC) X-FDA: 84579668166.22.52E5E11 Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) by imf14.hostedemail.com (Postfix) with ESMTP id 5C242100003 for ; Tue, 24 Mar 2026 04:25:41 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=VCisPo8C; spf=pass (imf14.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774326341; 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=xFm4rq63hk/RC8ec4idA1Wj6bRsPq9bmm+kOdtLr6mE=; b=gcljao3eG4K/34MN5Mcqk9XuSU+SQxTFeSQVoAzZJBhubpAX23ih2LUejw4NPyGyqrS4cW L8FXFfgPfXFsJ7Hr6iTOem5o7ekHLMHfxnm0RlQ/NSfWzqJaikI5/yZsY+2FrXzFL9xEv+ jdyvfmHT0w/FnnMArTZADaDZPeBbDQI= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=VCisPo8C; spf=pass (imf14.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774326341; a=rsa-sha256; cv=none; b=FF6m4gTb8OrojjBS7QZwl2tdxrBU/uE2fzJyjClnEfqVNzUGtDeTkGRY02cVm9vx54qAUT P+IcNBWbNv+cYApMuOXs+4N840iIIxo9q5Lwf4CkuZJVAA51ejMrzHwIhGwDrH+Nr54Aku t+QwzECECw6+inVd/zNstQ0fpzmNpEE= Message-ID: <138d9363-ab0c-4f5c-bedc-b326f5aaee91@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1774326339; h=from:from: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; bh=xFm4rq63hk/RC8ec4idA1Wj6bRsPq9bmm+kOdtLr6mE=; b=VCisPo8Co7n3knIGM0A0ZVk9KeDhkyF3dYJNyIngSsxp5cgCjpBS2vBIAqIineGlMW265t Uq314LeejaqmyZiE6GvJye2uYRmVqRhgEWRLaTivnDDhugIdiI4luxhrqq66i5SUKZiMwj nIUZDYgdo3d05U+icbURkSf2M1LGkwo= Date: Tue, 24 Mar 2026 12:25:16 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v6 30/33] mm: memcontrol: prepare for reparenting non-hierarchical stats To: "Harry Yoo (Oracle)" Cc: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, yosry.ahmed@linux.dev, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev, bhe@redhat.com, usamaarif642@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Yosry Ahmed , Qi Zheng References: <2d39ea5e-fd69-4acf-8518-a504f5f7a838@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5C242100003 X-Stat-Signature: r3sqfebpn7c8buhep57oqa559465t9da X-Rspam-User: X-HE-Tag: 1774326341-741004 X-HE-Meta: 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 KlKvEfXd mb6pTdhWe3P68SWf3antDSibCUtmLY1uRaTAuhbq5C6QxI7F1WUBdMyUVFGA+RQPVWk1huqkttP7eVUYpWDVxEMZG3/Qj7SAL/irDxFlXWK1ZP5j9Vg+E7FxkD5HLczDkl6IFl+9JitMnReOYvAxbDDQJv9xbseGsYr5Wj0rrNhG5zf0UyZzKSq6tP/+iQzwkHKhu Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/24/26 12:05 PM, Harry Yoo (Oracle) wrote: > On Tue, Mar 24, 2026 at 10:54:48AM +0800, Qi Zheng wrote: >> On 3/23/26 8:25 PM, Harry Yoo (Oracle) wrote: >>> On Mon, Mar 23, 2026 at 05:47:27PM +0800, Qi Zheng wrote: >>>> On 3/23/26 3:53 PM, Harry Yoo (Oracle) wrote: >>>>> On Thu, Mar 05, 2026 at 07:52:48PM +0800, Qi Zheng wrote: >>>>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>>>>> index 23b70bd80ddc9..b0519a16f5684 100644 >>>>>> --- a/mm/memcontrol.c >>>>>> +++ b/mm/memcontrol.c >>>>>> @@ -473,6 +501,30 @@ unsigned long lruvec_page_state_local(struct lruvec *lruvec, >>>>>> return x; >>>>>> } >>>>>> +#ifdef CONFIG_MEMCG_V1 >>>>>> +static void __mod_memcg_lruvec_state(struct mem_cgroup_per_node *pn, >>>>>> + enum node_stat_item idx, int val); >>>>>> + >>>>>> +void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg, >>>>>> + struct mem_cgroup *parent, int idx) >>>>>> +{ >>>>>> + int nid; >>>>>> + >>>>>> + for_each_node(nid) { >>>>>> + struct lruvec *child_lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid)); >>>>>> + struct lruvec *parent_lruvec = mem_cgroup_lruvec(parent, NODE_DATA(nid)); >>>>>> + unsigned long value = lruvec_page_state_local(child_lruvec, idx); >>>>>> + struct mem_cgroup_per_node *child_pn, *parent_pn; >>>>>> + >>>>>> + child_pn = container_of(child_lruvec, struct mem_cgroup_per_node, lruvec); >>>>>> + parent_pn = container_of(parent_lruvec, struct mem_cgroup_per_node, lruvec); >>>>>> + >>>>>> + __mod_memcg_lruvec_state(child_pn, idx, -value); >>>>>> + __mod_memcg_lruvec_state(parent_pn, idx, value); >>>>> >>>>> We should probably change the type of `@val` from int to val to avoid >>>>> losing non hierarchical stats during reparenting? >>>> >>>> The parameter and return value of memcg_state_val_in_pages() are both >>>> of type int, so perhaps we need a cleanup patch to do this? >>> >>> Yes! >>> >>> and @val in memcg_rstat_updated() too, I think. >> >> Right. >> >>> >>>> I will send a cleanup patchset to do this, which includes the following: >>>> >>>> https://lore.kernel.org/all/5e178b4e-a9e0-44dc-a18d-8c014365ee2f@linux.dev/ >>> >>> Thanks! >>> >>> Should that ideally be applied before this patchset? >> >> This would conflict with the current patchset. > > Right. > >> The v6 has been in mm-unstable for some time > > Right. > >> so I prefer to add a cleanup patchset to >> avoid interfering with the merge of this patchset. > > but it's a little bit more than a cleanup, no? > > I'd say without the followup, this patchset introduces a very subtle > (likely nobody would notice) functional regression visible on memcgs > with billions of pages. Right. > >> Otherwise, sending v7 might be more appropriate. > > I think it should be sent either as v7 or as part of v7.1-rcX. > (Whichever way Andrew prefers) OK, In any case I will first send out the cleanup/fix patchset for everyone to review. Thanks, Qi >