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 503DED64086 for ; Wed, 17 Dec 2025 07:28:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 94A446B0089; Wed, 17 Dec 2025 02:28:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 90A786B008A; Wed, 17 Dec 2025 02:28:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8094A6B008C; Wed, 17 Dec 2025 02:28:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 70C716B0089 for ; Wed, 17 Dec 2025 02:28:46 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 221871A0932 for ; Wed, 17 Dec 2025 07:28:46 +0000 (UTC) X-FDA: 84228135852.09.D181C9F Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) by imf30.hostedemail.com (Postfix) with ESMTP id 721DB80002 for ; Wed, 17 Dec 2025 07:28:44 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="qFETWJ3/"; spf=pass (imf30.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.174 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=1765956524; 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=PzAKpbiIZxa6n28+BpnjQ9tXWvyZHSCscw68X1Foo9A=; b=UZOcovoCKDvIy5gau6FteZK4C7jk46xavVYNFHSSUw9QXKH1ZYEVmqCHFINEcQXEldWqOu 3TW67zTlq2K+OoJ9gnbBu8V50KvpYEnommdieNq3ESBBaJuDAHi9Z5xajUTXIq5s1pM9+D b0QFqvK3Iid/ykYrm05GA4Y7ru4wYLM= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="qFETWJ3/"; spf=pass (imf30.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.174 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1765956524; a=rsa-sha256; cv=none; b=WRuCxMn69u4ysbWLm9uw6dX8adiTteYK1fYkElTU1fowW/SkR/Xb7zTniwxEMfOzA/4896 aIln7rmZAjA5YsuX9HwNHsf9nyWImjckoAdvVpoyJ+RLyn4Gknkj9FDXtukf4l+2Phb3Dc 1+XEX2YsA8etY6Kw0S97ZI7TP/26Sh8= 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=1765956517; 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=PzAKpbiIZxa6n28+BpnjQ9tXWvyZHSCscw68X1Foo9A=; b=qFETWJ3/QbdSXlWUUX5sj/GLxv/uSjNALIuZ6SkUIGRjkqLuFad+gZwNeXXCVqqGKcwF8m Ph4pcxZJZGxxofIQxCgpMmaoeumjFkDPE/0ZabisZiaJrL0RllkrAspiKspyj++VDnh8vH ee7Bw8gYmx4i0tjC6dQoLoP21p+2XUk= 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, 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng , Chen Ridong Subject: [PATCH v2 01/28] mm: memcontrol: remove dead code of checking parent memory cgroup Date: Wed, 17 Dec 2025 15:27:25 +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: rspam11 X-Rspamd-Queue-Id: 721DB80002 X-Stat-Signature: 767y6tkuz3ycozgraxpakzgbdt9ebryx X-HE-Tag: 1765956524-649100 X-HE-Meta: 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 JIpjBZzQ 6NqjkTGH1GgkHCrMHECuuPaDSf5uBjLl+WwMiqCl/mmeAot86aICsd08dZBpPveuu+JgThvD3Pun7wm/rlaHQL5m7EVJjBdDKIK+FMdV8W5oiOaAwx+YtDbvYm7h/28rOEJfZ3LfCJ2UpYbhP0Z6eJ7XFsJiRX/FcSIHQZllHOu52LVzxpkf2e4KUwSu04xW6lwK2inS1ee5OGXX6T/t8yHRWdL80wkZ/xQXDn8UIjobi5l8b78SLnb/cffiPdDvH+z5LHauVLMneW+JPedbsNnX+wF+twtkfrNjy X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 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 --- 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 e2e49f4ec9e0e..ae234518d023c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3331,9 +3331,6 @@ 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); /* @@ -3624,8 +3621,6 @@ 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) { -- 2.20.1