From patchwork Wed Apr 28 09:49:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12228439 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 396B8C433B4 for ; Wed, 28 Apr 2021 09:54:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A0F1B613E7 for ; Wed, 28 Apr 2021 09:54:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A0F1B613E7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 27D676B0070; Wed, 28 Apr 2021 05:54:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 22E1D6B0071; Wed, 28 Apr 2021 05:54:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0A7736B0072; Wed, 28 Apr 2021 05:54:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0212.hostedemail.com [216.40.44.212]) by kanga.kvack.org (Postfix) with ESMTP id E2E026B0070 for ; Wed, 28 Apr 2021 05:54:11 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 9CD2252BF for ; Wed, 28 Apr 2021 09:54:11 +0000 (UTC) X-FDA: 78081315102.09.F81DEF3 Received: from mail-pg1-f182.google.com (mail-pg1-f182.google.com [209.85.215.182]) by imf11.hostedemail.com (Postfix) with ESMTP id 12F632000241 for ; Wed, 28 Apr 2021 09:53:55 +0000 (UTC) Received: by mail-pg1-f182.google.com with SMTP id j189so613751pgd.13 for ; Wed, 28 Apr 2021 02:54:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=m1CFbU+mCktpHQ1dKqvusnGfjIT06imnu2MiKnHY6nk=; b=v4VjCZlNqoTtno1oSp5L516Q2Oq7puICK/nvOGS2G21b+Zf8dDbqpbPxbXBFaxZyPX +9XX3GF59psC7dYErKQ1Wd1WNsQ+vI7dYeuNft1Ozh+O1wGMo22QQASc86eHBg+p/taX 0nt80fb8lIzpAY70hZqGDF1imMiyDa8M/NsPH3xct7MNOLYD0cR3yy9FOLpKSE51hOFh hoyOIPv/848DsYPW8PmuRPui51Ovt41Nq0xw0czJphN9QGOR5l8mxqA0xVizRBGv80Dm V7n+ezDBiebnuPwdwgVwZO118XmqHJVIwU+D7QP07FQozcA5XNWoYM4DmScmZFDqI3Fp cdGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=m1CFbU+mCktpHQ1dKqvusnGfjIT06imnu2MiKnHY6nk=; b=hL1WghzfMHcIeWZbaelg5Zc80dSdQ1B4+7ZFVRFeNZ1m1q2837bc22qKkfNkOrE7en DtMRTlufa2YqNr2xx4pJ4muOVbfc9X/cCDQ82hZZ8gyVwI/tN0CMPC+4pIR8GbTA8g4J 5EhmYy+qZms/SFe62kaRLFcQbb0hF6DKbE1/Vl5FhI1dK+TxwA3ah0SI38dbtW4T+dbn 535NyOh9nqV9kj7HvxyzzkGIw4G+PLkgB6XE8uAVktgVGwsdYgY68AUgFfpDwqTCLyq+ TXHjDmNz7ZWrNGG19SpfbqYbX65rFbrrqxJtIrcS/gWQsi1t1qkjkBKZsZes+zNQYGec WElg== X-Gm-Message-State: AOAM530CypgGeJCddMK/wJ8fsDq6/KxsHRyHBqE0q6JDg6Na3gftnrCZ Dvq2wMRBcu0iO8bsi1jazbWAFA== X-Google-Smtp-Source: ABdhPJw6KaQEv1gmE2Ru2d5aoT7DK6/dT4q9Q9aoINopiR0PMuD4/fmPAfJYaLngGk2J5Pm10PwxBA== X-Received: by 2002:a62:7646:0:b029:27a:29b6:e10b with SMTP id r67-20020a6276460000b029027a29b6e10bmr8361616pfc.14.1619603650322; Wed, 28 Apr 2021 02:54:10 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.233]) by smtp.gmail.com with ESMTPSA id x77sm4902365pfc.19.2021.04.28.02.54.05 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 28 Apr 2021 02:54:10 -0700 (PDT) From: Muchun Song To: willy@infradead.org, akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, shakeelb@google.com, guro@fb.com, shy828301@gmail.com, alexs@kernel.org, alexander.h.duyck@linux.intel.com, richard.weiyang@gmail.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Muchun Song Subject: [PATCH 2/9] mm: memcontrol: remove kmemcg_id reparenting Date: Wed, 28 Apr 2021 17:49:42 +0800 Message-Id: <20210428094949.43579-3-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210428094949.43579-1-songmuchun@bytedance.com> References: <20210428094949.43579-1-songmuchun@bytedance.com> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 12F632000241 X-Stat-Signature: sm9n3omr7ffqpz36fqfamc4gdymotdp5 Received-SPF: none (bytedance.com>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail-pg1-f182.google.com; client-ip=209.85.215.182 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619603635-251028 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: Since slab objects and kmem pages are charged to object cgroup instead of memory cgroup, memcg_reparent_objcgs() will reparent this cgroup and all its descendants to the parent cgroup. It means that the new parent memory cgroup can be returned by mem_cgroup_from_obj() which is called from list_lru_from_kmem(). This can make further list_lru_add()'s add elements to the parent's list. So we do not need to change kmemcg_id of an offline cgroup to its parent's id. This is just waste CPU cycles. Just remove those redundant code. Signed-off-by: Muchun Song --- mm/memcontrol.c | 20 ++------------------ 1 file changed, 2 insertions(+), 18 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 64ada9e650a5..21e12312509c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3485,8 +3485,7 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) static void memcg_offline_kmem(struct mem_cgroup *memcg) { - struct cgroup_subsys_state *css; - struct mem_cgroup *parent, *child; + struct mem_cgroup *parent; int kmemcg_id; if (memcg->kmem_state != KMEM_ONLINE) @@ -3503,22 +3502,7 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg) kmemcg_id = memcg->kmemcg_id; BUG_ON(kmemcg_id < 0); - /* - * Change kmemcg_id of this cgroup and all its descendants to the - * parent's id, and then move all entries from this cgroup's list_lrus - * to ones of the parent. After we have finished, all list_lrus - * corresponding to this cgroup are guaranteed to remain empty. The - * ordering is imposed by list_lru_node->lock taken by - * memcg_drain_all_list_lrus(). - */ - rcu_read_lock(); /* can be called from css_free w/o cgroup_mutex */ - css_for_each_descendant_pre(css, &memcg->css) { - child = mem_cgroup_from_css(css); - BUG_ON(child->kmemcg_id != kmemcg_id); - child->kmemcg_id = parent->kmemcg_id; - } - rcu_read_unlock(); - + /* memcg_reparent_objcgs() must be called before this. */ memcg_drain_all_list_lrus(kmemcg_id, parent); memcg_free_cache_id(kmemcg_id);