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 D5023EA854A for ; Mon, 9 Mar 2026 02:59:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0CD236B0088; Sun, 8 Mar 2026 22:59:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 07AD76B0089; Sun, 8 Mar 2026 22:59:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EC8456B008A; Sun, 8 Mar 2026 22:59:48 -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 D9CC06B0088 for ; Sun, 8 Mar 2026 22:59:48 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 5B7EBC3D02 for ; Mon, 9 Mar 2026 02:59:48 +0000 (UTC) X-FDA: 84525019656.09.ADF50E6 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) by imf05.hostedemail.com (Postfix) with ESMTP id 6BE10100006 for ; Mon, 9 Mar 2026 02:59:46 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=FJawJpKa; spf=pass (imf05.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.170 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=1773025186; 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=surD7Tl7I0c7IM/NAN7h4/O0mH6dbWmZP+2JPPoPahM=; b=3/DGy9l+I3CAYTBDthmO2IJYbe1NadGTn3/FZZHRmhBGc6sELV1IoD2JfAI8bF0UCmahSE RoFM2bkQF15TeFlVoi9+oa4kc+fmy6Lm3mkAe71fWhvNH7SauCDlWRbbfr0dZeG5hPCevy aDyuuHpcLXM/Yj7pJ1zadoTvHDP6eSc= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1773025186; a=rsa-sha256; cv=none; b=KjtoKjyYaZ12UPJ9Di74xw/c75B+vCTwdWErIvMPM2pwXdf2IkCTaxhDhsyX6wrPyEZgmz 1pvPPfgNlPWGJOOmPjomPp0gbAtQgSvPT6FcSjc0vxGIWIe+mEBgRR6N2DG8W4uu2WXCTj r0m5HTdAq1cx1+OgeAvnkxXHHe1cQGw= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=FJawJpKa; spf=pass (imf05.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.170 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1773025183; 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=surD7Tl7I0c7IM/NAN7h4/O0mH6dbWmZP+2JPPoPahM=; b=FJawJpKa2+SghPS7x3wAb1/ADkqlaG+EU48QgAFLhye7ep1KXmfv8aR211KO6QMm+aM9jE lkSfHq7NYA6CmA4qgbrbz1Bb+64sic2GD+OsuriZ38V6yHQAVTjuMN9h63nPZs8OqpFDZL E7/eoswn88XvnfZ+A7mJ8TC5NNgcmWI= Date: Mon, 9 Mar 2026 10:59:18 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v6 31/33] mm: memcontrol: convert objcg to be per-memcg per-node type To: Usama Arif 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, Qi Zheng References: <20260306202931.3878822-1-usama.arif@linux.dev> <898e8ca7-efcb-4bd7-8016-871b37be830e@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <898e8ca7-efcb-4bd7-8016-871b37be830e@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: x7btssfh1w5wm5e89jwyxr1wq5ezgq5z X-Rspam-User: X-Rspamd-Queue-Id: 6BE10100006 X-Rspamd-Server: rspam12 X-HE-Tag: 1773025186-887675 X-HE-Meta: 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 pkfIiM14 Acl+/vlNOXKS5fcNY+bnSOxM9Qd9A+2X0wVP1QDeNod56Sd324YEADnsUbHxBIVNeDZS/YUjOF0COAB6pjGALNxis1CzqyuAZDIyxTjW45R7RY6h9bqUpe3bavQujKEF+9AzIXZB5Y7SVRi1z2ibmkvp80GKc6bLuyXTJ6pInHoFZOtOy7goj1+6RqBaHW/mndEq0xkF2ZXDE7WwC3vY6cZkrmkCu6iBovnml/ja0uGPxLG2BUSWxLXQE4XS2sl7z4sUWygMWo9641nv2rhbrAs6fb0xvqCMZpQb2HBoQPltHiLM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/7/26 7:08 PM, Usama Arif wrote: > > > On 07/03/2026 08:51, Qi Zheng wrote: >> Hi Usama, >> >> On 3/7/26 4:29 AM, Usama Arif wrote: >>> On Thu,  5 Mar 2026 19:52:49 +0800 Qi Zheng wrote: >>> >>>> From: Qi Zheng >>>> >>>> Convert objcg to be per-memcg per-node type, so that when reparent LRU >>>> folios later, we can hold the lru lock at the node level, thus avoiding >>>> holding too many lru locks at once. >>>> >>>> Signed-off-by: Qi Zheng >>>> Acked-by: Shakeel Butt >>>> --- >>>>   include/linux/memcontrol.h | 23 +++++------ >>>>   include/linux/sched.h      |  2 +- >>>>   mm/memcontrol.c            | 79 +++++++++++++++++++++++--------------- >>>>   3 files changed, 62 insertions(+), 42 deletions(-) >>>> >>> >>> [...] >>> >>>> @@ -4087,7 +4100,13 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css) >>>>       xa_store(&mem_cgroup_private_ids, memcg->id.id, memcg, GFP_KERNEL); >>>>         return 0; >>>> -free_shrinker: >>>> +free_objcg: >>>> +    for_each_node(nid) { >>>> +        struct mem_cgroup_per_node *pn = memcg->nodeinfo[nid]; >>>> + >>>> +        if (pn && pn->orig_objcg) >>>> +            obj_cgroup_put(pn->orig_objcg); >>> >>> Is it possible that you might call obj_cgroup_put twice on the same cgroup? >> >> Oh, I think you are right. Here pn->orig_objcg was not reset to NULL, so >> obj_cgroup_put() will be called in __mem_cgroup_free() again. >> >>> >>> If css_create fails, css_free_rwork_fn is queued, which ends up calling >>> mem_cgroup_css_free which calls obj_cgroup_put again? >>> >>> Maybe adding pn->orig_objcg = NULL overhere after obj_cgroup_put >>> is enough to prevent the double put from causing issues? >> >> Agree. >> >> Like this? >> > > Yes below looks good! Might be good to add a comment as well why setting > it to NULL. OK, will add the following comment: /* * Reset pn->orig_objcg to NULL to prevent obj_cgroup_put() * from being called agagin in __mem_cgroup_free(). */ > >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index 992a3f5caa62b..e0795aec4356b 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -4140,8 +4140,10 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css) >>         for_each_node(nid) { >>                 struct mem_cgroup_per_node *pn = memcg->nodeinfo[nid]; >> >> -               if (pn && pn->orig_objcg) >> +               if (pn && pn->orig_objcg) { >>                         obj_cgroup_put(pn->orig_objcg); >> +                       pn->orig_objcg = NULL; >> +               } >>         } >>         free_shrinker_info(memcg); >>  offline_kmem: >> >> If there are no problems, I will send a fix patch later. >> >> Thanks, >> Qi >> >>> >>>> +    } >>>>       free_shrinker_info(memcg); >>>>   offline_kmem: >>>>       memcg_offline_kmem(memcg); >>>> -- >>>> 2.20.1 >>>> >>>> >> >