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 9ACEBF3094F for ; Thu, 5 Mar 2026 11:54:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1128F6B008C; Thu, 5 Mar 2026 06:54:14 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0DB2E6B0092; Thu, 5 Mar 2026 06:54:14 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F15A16B0093; Thu, 5 Mar 2026 06:54:13 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id E1F076B008C for ; Thu, 5 Mar 2026 06:54:13 -0500 (EST) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 937D18C665 for ; Thu, 5 Mar 2026 11:54:13 +0000 (UTC) X-FDA: 84511851186.07.E5837AC Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) by imf16.hostedemail.com (Postfix) with ESMTP id E0B0E18000B for ; Thu, 5 Mar 2026 11:54:11 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=K94LyqzX; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.172 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=1772711652; 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=z+WPL9kwYroTQ5Eem34z+ZcGTSApGRGWSWwpIHeB5ijnW+M8JU48QuNpY0lDIxidfg20GL sekLse+QmgW8R4JOpSZQK0DFFvDA50mG/Xkc6xRGMB3S26Hm20jro+6RezfsXhXSl0UBKT T5prqLrofv8bPz8IGX5vhP0Ho/gWXxE= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=K94LyqzX; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772711652; a=rsa-sha256; cv=none; b=RoVmQIQAseg9IlShde/HhLJlg886MIfjDus2nIer4eVgdbsDlSA09iD+ZmN1ZvU9UV8yBl PO3HWMLsK/D2bobeJN/NyA5p5u37Z+j4KI0P7ZIL1L613irtxgP0h5CYuPLaU+7naSzPdR aMligaA9jm7jEz6mJJJA4Gw3MrlfsZQ= 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=1772711649; 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=K94LyqzXS3gex8zFVnJgklSMCyl1mw39v9eFcSQDt3tLYoGbqG58fueQtSLfGedD0qbMWL IaWKIO1I3HWL/QISzw6kxwulQCi7W7F0VQ7rswv9IR110N0ONu0cttNUvLRj5hIkQZFpLY vQ7oRfBVai5yz3N4q7P3MJsT4Nr+388= 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 v6 01/33] mm: memcontrol: remove dead code of checking parent memory cgroup Date: Thu, 5 Mar 2026 19:52:19 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E0B0E18000B X-Stat-Signature: bafpugm6owxsu4aqbd5eizc9pjie8o7j X-Rspam-User: X-HE-Tag: 1772711651-473497 X-HE-Meta: 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 WGLcpXIR 1TVSh2TjAnAjCG0FD4I0+zGBm8nT1JrQdpT+61RoDRCJXhqYBAkUHychiVgkh4s+htl4ydqnK+oHfK0vHBWe/5JvuXH0DLsUHS5GC+elk+M2bBc55f2HSYdBxOOS/W1Ow/Zwgf3/ZOhXYp06kfNofmHo7beb2y9R2llc7Coe16yrwuU/OSmhfCd6oQTYNYlCI7EbdKVHAVQBmXO//j+Xgv23ctZOEOJ/304gzzBaIuDVhtseAydmLAb5NXrQJ87StPWvqEy44tAIjl+Gab0jbRcEfCWLtYmy3rhCC 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