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s=arc-20220608; d=hostedemail.com; t=1763629679; a=rsa-sha256; cv=none; b=LyuvviKpvW7ivN4L0mhxycGdK98OyDWy+fyh5wcT1qZlDDJVniYte4+aMzomIxaXk1RiWp yy12YiBYITYcpy8OvBsQs0jok8V2Ti3Z06zQnf2jsIugYNZS0VV6J3au5npViTXgCKpmJn sOW1567smRit4etSlagm8E+xKPgWIy0= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of chenridong@huaweicloud.com designates 45.249.212.51 as permitted sender) smtp.mailfrom=chenridong@huaweicloud.com; dmarc=none Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4dBstM6Sf3zYQv5C for ; Thu, 20 Nov 2025 17:07:07 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.75]) by mail.maildlp.com (Postfix) with ESMTP id 7CB991A14F9 for ; Thu, 20 Nov 2025 17:07:49 +0800 (CST) Received: from [10.67.111.176] (unknown [10.67.111.176]) by APP2 (Coremail) with SMTP id Syh0CgC3YXhk2h5pdWOOBQ--.29493S2; Thu, 20 Nov 2025 17:07:49 +0800 (CST) Message-ID: <0d78a4cf-0973-4874-ab6a-978621a17068@huaweicloud.com> Date: Thu, 20 Nov 2025 17:07:47 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 01/26] mm: memcontrol: remove dead code of checking parent memory cgroup To: Qi Zheng , hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng References: Content-Language: en-US From: Chen Ridong In-Reply-To: Content-Type: text/plain; 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Hence, it's safe to > remove the check on the returned value of parent_mem_cgroup(). Remove the > corresponding dead code. > > Signed-off-by: Muchun Song > Acked-by: Roman Gushchin > Acked-by: Johannes Weiner > Signed-off-by: Qi Zheng > --- > mm/memcontrol.c | 5 ----- > mm/shrinker.c | 6 +----- > 2 files changed, 1 insertion(+), 10 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 93f7c76f0ce96..d5257465c9d75 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3339,9 +3339,6 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg) > return; > > parent = parent_mem_cgroup(memcg); > - if (!parent) > - parent = root_mem_cgroup; > - > memcg_reparent_list_lrus(memcg, parent); > > /* > @@ -3632,8 +3629,6 @@ struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) > break; > } > memcg = parent_mem_cgroup(memcg); > - if (!memcg) > - memcg = root_mem_cgroup; > } > return memcg; > } > diff --git a/mm/shrinker.c b/mm/shrinker.c > index 4a93fd433689a..e8e092a2f7f41 100644 > --- a/mm/shrinker.c > +++ b/mm/shrinker.c > @@ -286,14 +286,10 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) > { > int nid, index, offset; > long nr; > - struct mem_cgroup *parent; > + struct mem_cgroup *parent = parent_mem_cgroup(memcg); > struct shrinker_info *child_info, *parent_info; > struct shrinker_info_unit *child_unit, *parent_unit; > > - parent = parent_mem_cgroup(memcg); > - if (!parent) > - parent = root_mem_cgroup; > - > /* Prevent from concurrent shrinker_info expand */ > mutex_lock(&shrinker_mutex); > for_each_node(nid) { LGTM. Reviewed-by: Chen Ridong -- Best regards, Ridong