From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta1.migadu.com (out-170.mta1.migadu.com [95.215.58.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E28BD2EBBA1 for ; Sat, 7 Mar 2026 08:53:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772873591; cv=none; b=IZGBceNp2B/srQWDe2lVY8ZWRmYTmn6fuJ2o07aBx2Pe/BJS9ysAhpJ65ItT6URdP9s67AlE5yw8OjnYdP1fAs8jcUdSC4fCHRG55vIW3QLlJO1NP7NobW48dKljdiN+b5JsalRsYGv2FEcPB0pfPLkAs2NCanba7SnCDr7Vyhs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772873591; c=relaxed/simple; bh=FYyP8ZpTDEbn360Vm8yQAAs5kfBZBkodLImqHzZTVpI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=j/vg6x8Lh2C3+N4qJLXPgv4EVBBtcUWtKCHNGt1KiIX4mqsl2qtI9wJSeHC7uprlDhroZb1K0tV36GDylTmouZF3ZPhFtOe5xK5FbUOvtVZNFQB26BbQvWAlH7zUVDeYSkWvc0ooCIdY0VXr3yQXbX67g3+ZRMP8a2Za7pfZYEc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=CawqzaEc; arc=none smtp.client-ip=95.215.58.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="CawqzaEc" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772873587; 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=BTpdDjrX0wTiL0fAhrePIJwxDS9K/k1k3ZXc5DUWgFA=; b=CawqzaEcU9hO9vJW+5g8ONlJ2RUwoSXjBsrHnHWghOAHhDNG5ovYnEL5GkizH5j+vQLW/u Smfzz/V5alCB0t6HJYZvtsS7YbVIFnMwRLlmk2UdFl5qh6hb18+cZxpoAZZ6kVemODYg/j 1uIpWYQGZmSj/3ji+7RQAzkA8EgqoCY= Date: Sat, 7 Mar 2026 16:51:58 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <20260306202931.3878822-1-usama.arif@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT 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? 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 >> >>