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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 77D50C433ED for ; Wed, 28 Apr 2021 09:54:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4102261422 for ; Wed, 28 Apr 2021 09:54:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238468AbhD1Jy5 (ORCPT ); Wed, 28 Apr 2021 05:54:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238456AbhD1Jyz (ORCPT ); Wed, 28 Apr 2021 05:54:55 -0400 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7530C06138B for ; Wed, 28 Apr 2021 02:54:10 -0700 (PDT) Received: by mail-pf1-x432.google.com with SMTP id a12so1056924pfc.7 for ; Wed, 28 Apr 2021 02:54:10 -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=dVvo2TVZUmGbL3OIJJRnyfiH5PYvdHd/eRlM+FbrAlI1DoYY2d8qCz07vsA7sqLhja pB/PZc+xrB3dJpEtYjnfgmk8STf00yusKKy22MRoclom/1zpJqPMMwuvWcd696sKGVH1 75vXNOWqzjDcJLws0sA8nKvOOuU7uejLYcGwRda0vZFj9bdOI0Sw6DuAsemjlNmVYEdi ZbkJgEBhhk26JyAu3yokSnwJrsPMYNwaYivzqCvo77YqmOJdMJAkA3TI2jq7rbffrRGV VhRcx4lrSaSoYgEUDidVhMMS4v2wAvPpPWh3Tr4LvzBDQ3Kfxbqv/QymmrDx2ALopeTg dGFA== X-Gm-Message-State: AOAM532e5pPgA+H39eX0pQa2D9IHBlCcMMQwAhorWfbyYTaBbzgtbyjW DybyFrYudF6fIYeW6iA5x63bLQ== 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 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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); -- 2.11.0