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 1AFACEFD200 for ; Wed, 25 Feb 2026 07:49:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7DF356B0088; Wed, 25 Feb 2026 02:49:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7BCE76B008A; Wed, 25 Feb 2026 02:49:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6BF576B008C; Wed, 25 Feb 2026 02:49:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 5CB046B0088 for ; Wed, 25 Feb 2026 02:49:51 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 14970B977F for ; Wed, 25 Feb 2026 07:49:51 +0000 (UTC) X-FDA: 84482204982.06.255ED2A Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) by imf19.hostedemail.com (Postfix) with ESMTP id 669AB1A000B for ; Wed, 25 Feb 2026 07:49:49 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="n/za7M6f"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf19.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.171 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772005789; a=rsa-sha256; cv=none; b=4miX2mU5rjDFdbudgJTg2DjWUw4YV2FyzaEKGMQclcVW4i33c9RiKASokfbFKagyTgJLDs 0bxybAxfTzAaqaHusLyrF3kUVQFSfUMbTQayeTO0UfSlN8rTD0z8l+Z3f56bNcWSSr/cTJ onwy9FUEyhsOMKwuTCyivAyP+btL85c= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="n/za7M6f"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf19.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.171 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772005789; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=slvzxnQOZnGyEx6uyl7ed+CIq1Y9lBOT7LEWCAJSIOk=; b=f3h9HWVlbAwNij/wLm0dUJtvMQJWLJf9SuSoqNv2K8jXVulO7/kXjwc7WLe7DS/0Q3pX/L svUjHB01TaDxqkHHSJudcq1U7NSny9nl3oKny7sRZEWoA5ieYSPteJlH97NfBPSoFBfkGH sjI1/GcfgpEmBEaymRVgwXYX31DNFfo= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772005787; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=slvzxnQOZnGyEx6uyl7ed+CIq1Y9lBOT7LEWCAJSIOk=; b=n/za7M6fo6nAu4gWx7thBhD988RRJ+hxPdZ8vV4kFz0EnhpV4KBccby0iZimCxWy9Fs2oX ZK5scZWB3gpITU0egFxM6O50nOnKNbEwwGljhP0QCXEPE8tfSZrgPg+YZdPyhJZgiEiWEE wc0pyCUup3cBHzoFwWpNFLS4iG1HQn4= From: Qi Zheng To: 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng , Chen Ridong Subject: [PATCH v5 01/32] mm: memcontrol: remove dead code of checking parent memory cgroup Date: Wed, 25 Feb 2026 15:48:34 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 669AB1A000B X-Stat-Signature: 7wce418w5oxh86s89to6pzmb5ks7hryu X-HE-Tag: 1772005789-481169 X-HE-Meta: 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 Km45bRud OuedZRWike+eCSEffoUY2PyOxB+TEqVosHak5xQ0CW4h009CCxswV+tbDDACnHYvs5OtNVUS6PK8csuDtduiDX6Zr0DmY7gWVw5sh68of5mL5+j5FCPe1QO7rEAIGNNgk20fRVJLF0u5JUrLt/KLAA+rHbc23BbS+ZQuGXIJH/rlPyI4HfNbQ37KKHHylC02zFEmlT2ol4Nxxa29yXV667umrUFVG7Jbd6wU9uH9ny6F9/7QmNpuZdJPbiV8zQDFzb8XAphD6Y5tNSoputT7TRZiEY2ZaH0H5bfeu Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Muchun Song Since the no-hierarchy mode has been deprecated after the commit: commit bef8620cd8e0 ("mm: memcg: deprecate the non-hierarchical mode"). As a result, parent_mem_cgroup() will not return NULL except when passing the root memcg, and the root memcg cannot be offline. 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 Reviewed-by: Harry Yoo Reviewed-by: Chen Ridong Acked-by: Shakeel Butt --- 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 db59fad3503f2..aab863e1822d4 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3424,9 +3424,6 @@ 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); /* @@ -3706,8 +3703,6 @@ struct mem_cgroup *mem_cgroup_private_id_get_online(struct mem_cgroup *memcg, un 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 94646ee0af63b..4cd33222256ef 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) { -- 2.20.1