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 386FACA600E for ; Thu, 8 Oct 2026 09:56:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1F6196B008A; Thu, 8 Oct 2026 05:56:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1A6906B008C; Thu, 8 Oct 2026 05:56:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 095E96B0098; Thu, 8 Oct 2026 05:56:34 -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 DD9A26B008A for ; Thu, 8 Oct 2026 05:56:33 -0400 (EDT) Received: from smtpin18.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 4BC6EA051E for ; Thu, 8 Oct 2026 09:56:33 +0000 (UTC) X-FDA: 85299004266.18.9D1D009 Received: from out30-110.freemail.mail.aliyun.com (out30-110.freemail.mail.aliyun.com [115.124.30.110]) by imf15.hostedemail.com (Postfix) with ESMTP id 7330EA0006 for ; Thu, 8 Oct 2026 09:56:30 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b="g9fC/RVr"; spf=pass (imf15.hostedemail.com: domain of qinyuntan@linux.alibaba.com designates 115.124.30.110 as permitted sender) smtp.mailfrom=qinyuntan@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=1791453391; 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=1c2mwR8cYOL6Ygo+f93Zr8TE7ypOMqMWTVG83TPWuJk=; b=QKMSrEF91eNL/jWSBe7sEGBmfwFqMgtepsHbvCq5KRoVI/LIZFF84LopE5CUkjYQ3lRSCo hA1E9dKPSKLtMJVjT4a+6cYO4mXezzGSgiK4+d2rwFg/ysvADyiWrbh9nG4m592cT/FtIH ruWTSPzH3Jn2jRn/0mvF2rl0PkE7MPg= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b="g9fC/RVr"; spf=pass (imf15.hostedemail.com: domain of qinyuntan@linux.alibaba.com designates 115.124.30.110 as permitted sender) smtp.mailfrom=qinyuntan@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1791453391; b=Nj22vBL92/CoWASPEP5dLDxsR5OrDR/6AcXYPWiNtIP/eh3OS1cFtL9QbkXxZrl4m4277A 0cwgq4uQTB0r3HoEgHE7e1vAfmgP9RQcylW9xAcQ3P2nKS2dSimwDxJj4NM1oqNPXCe074 o/ybMTr3zW7ddRvFYGVFzgjDWe1RbTE= DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1791453387; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=1c2mwR8cYOL6Ygo+f93Zr8TE7ypOMqMWTVG83TPWuJk=; b=g9fC/RVrCE3TmzDiiOeo4Fn1zK21Ex0aEyL4TlqHPXlMT1hj+WxQYB06xQsFCPv/C1ZB8WU2bfpyQN+QGaIrxff8KbqalZixj0+GZ0ttsZzzyp2EoMbkhAEAF6JMHXPf63XSRxftjUzJTYrv5C6H6iXAGf+Kc+xo3Z0lpZfZsO0= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033045133197;MF=qinyuntan@linux.alibaba.com;NM=1;PH=DS;RN=21;SR=0;TI=SMTPD_---0XCO8HAT_1791453384; Received: from 30.178.85.189(mailfrom:qinyuntan@linux.alibaba.com fp:SMTPD_---0XCO8HAT_1791453384 cluster:ay36) by smtp.aliyun-inc.com; Thu, 08 Oct 2026 17:56:26 +0800 Message-ID: <776ea9bf-88db-44d5-a80e-eaa958294bab@linux.alibaba.com> Date: Thu, 8 Oct 2026 17:56:23 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/4] mm: memcontrol: drop kmemcg_id and use the memcg ID for list_lru indexing To: Gregory Price Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , =?UTF-8?Q?Michal_Koutn=C3=BD?= , David Hildenbrand , Zi Yan , Baolin Wang , Usama Arif , Dave Chinner , Qi Zheng , Yosry Ahmed , Nhat Pham , Chengming Zhou , Xunlei Pang , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260907110111.2286932-1-qinyuntan@linux.alibaba.com> <20260907110111.2286932-2-qinyuntan@linux.alibaba.com> From: Qinyun Tan In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 7330EA0006 X-Rspam-User: X-Stat-Signature: 3dje33e98ayziezp11phy3kfm5bu4gx7 X-HE-Tag: 1791453390-23565 X-HE-Meta: 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 bdxzm0KQ Zi0LIVraZSi71YDdy21GQQmAai7FPO67VuD2j0Gl+TlEjz7h6DWUEHJxxesgzTKLx0bdWFVnEJt3mtbqQwX8gFwZUwVb9cTT0a94c3ZfwuXA1PhkqHULzdBE5/LSNLmwQanUbtP/s59GVHSzgESHomNBZV0iXqYEenl4ihs1yw/NDs2PcQBU3/M+OUJBl2yxcKkhi29Q3DbotMKQw4FK11DWAG/NtlyUBKb22HM+lTLrY2dG/2+uzwlbF8ZqHzCekU6luGBTgr4wrwZFFtAWTtjwr4fDU9dFDzzVlnotL7aCJMTUN/XVsOnBCaTDEhpTxLxVKmjJa7CrNlZKwrLZfH0w3+QC50eulO7FK Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi, Gregory On 9/23/26 11:45 AM, Gregory Price wrote: > On Mon, Sep 07, 2026 at 07:01:08PM +0800, Qinyun Tan wrote: >> kmemcg_id is a copy of the memcg ID assigned in memcg_online_kmem(), >> and is only used as the list_lru xarray index. With >> cgroup.memory=nokmem the assignment never happens, so every memcg >> resolves to the per-node lists. The next patch needs the index to >> work under nokmem as well, so drop the copy and use the memcg ID. >> >> The ID works just as well as the copy did: root and NULL still >> return -1 and use the per-node lists, and the ID is only released >> after the list_lru reparenting, so a stale or recycled ID can never >> reach a live list_lru entry. >> >> The early return of memcg_offline_kmem() under nokmem is dropped as >> well, so the reparenting also covers lrus that stay memcg aware >> without kmem accounting. >> >> Signed-off-by: Qinyun Tan > > This breaks an assert in memcg_struct_check - i think you want to drop > this line as well > > --- > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 5d7a26c91610..fcba9eb55659 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -5886,8 +5886,6 @@ static void __init memcg_struct_check(void) > private_id_objcg); > CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_read_mostly, > private_id); > - CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_read_mostly, > - kmemcg_id); > CACHELINE_ASSERT_GROUP_MEMBER(struct mem_cgroup, memcg_read_mostly, > oom_group); > Good catch, thanks! I missed the layout assertion when removing the field. Andrew spotted the same issue in v3 as well. I will fold the fix in when I send out the next revision. Thanks for taking a look at the series! Qinyun Tan