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 D7F52E91298 for ; Thu, 5 Feb 2026 08:56:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2F6CB6B0092; Thu, 5 Feb 2026 03:56:41 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2A0846B0093; Thu, 5 Feb 2026 03:56:41 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1B01A6B0096; Thu, 5 Feb 2026 03:56:41 -0500 (EST) 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 0922D6B0092 for ; Thu, 5 Feb 2026 03:56:41 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id B17161C277 for ; Thu, 5 Feb 2026 08:56:40 +0000 (UTC) X-FDA: 84409797360.09.D2A5EC4 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) by imf28.hostedemail.com (Postfix) with ESMTP id 0BBDFC0008 for ; Thu, 5 Feb 2026 08:56:38 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LRkYdPgJ; spf=pass (imf28.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.188 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=1770281799; 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=8dwQ4ivLYmtr2b7Y96V9uq4Z1sJnMO6h/66mf7WpDnM=; b=jczaFeAZeEfmni432f6EdjAsdd/RTOLUI+n/wjE6dmyJf3wzLXE17NCLbQuP2orqpUTXgC XBtQnxvh1fTE8J0NmpFLEqHbqDi1nYdYXleUyGH2puEXkV4HEC6LWYrapf6KSgQ2GNi0b0 8/W5bW/+qBo0uJhc8IBM145PEeTZ/+Q= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LRkYdPgJ; spf=pass (imf28.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.188 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=1770281799; a=rsa-sha256; cv=none; b=nd6yiP7l+iD4ntUNC0KAqUOufJ7WmfA7bBP5kAq4dojA5q/M4i8Isz7W9Sq+DiewR2laMt 9Hcs6lpJlnQKD4oxrZCdoFwhOmeKTHEAAx6+iytu8wfLEsxYai37YDUD4z96jLbzPBbjVS VJeZvXZO0JQcU4iDCDqm0Hhusk+MZ10= 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=1770281793; 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=8dwQ4ivLYmtr2b7Y96V9uq4Z1sJnMO6h/66mf7WpDnM=; b=LRkYdPgJMCg2yjFaMTf80KajUiQErFG88Y0kog/cwdqa1bHO+OtW05ZgTqLE1/arPXY1+W aACjXS6lz59xu6WJtfOPo4K9uMb4WDVqi3NRU8Gi3mxXmwBi+NwA45b3uNgqLVAikdmjBH 17tAzzirNBlIYG15ZnmxX0/A55Qm1o0= 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng , Chen Ridong Subject: [PATCH v4 01/31] mm: memcontrol: remove dead code of checking parent memory cgroup Date: Thu, 5 Feb 2026 16:54:30 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0BBDFC0008 X-Stat-Signature: 49hgrs88ox9dagajzkry465ukxbi1hgm X-Rspam-User: X-HE-Tag: 1770281798-554471 X-HE-Meta: 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 NDmiHkbl yG8eWJaTcSiH/Bm2eUQbXCg/D3dewT3DCKAOEXiWahU0D1OFieXHOb7UHubiAZLLf50hGltl/MdUSp6uc8kxxpHMVdoi/DbQVy2sWzCxtPl4u0mtGavbFEsefDIFqsabz9ZzpScOoRdSKYYhCoQQBP7ihrrrwIsGqvtUlRsUvesGnOc5VyFXicAxKu6r3P3eVZOxP9UgoB6xwphDLB43NrGCBEej509OoOjkhs/8UakjFHpnKCbquaHN9/Wx8mwIoaJHtco2kd+dYJl2znb/4x+YFT03lG6WyMSMO 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 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 f2b87e02574e0..43dbd18150e97 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3352,9 +3352,6 @@ 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); /* @@ -3645,8 +3642,6 @@ struct mem_cgroup *mem_cgroup_private_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