From patchwork Tue May 11 10:46:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12250571 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,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 800E0C433ED for ; Tue, 11 May 2021 10:51:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C0FB613CF for ; Tue, 11 May 2021 10:51:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231339AbhEKKwl (ORCPT ); Tue, 11 May 2021 06:52:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231410AbhEKKwg (ORCPT ); Tue, 11 May 2021 06:52:36 -0400 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9A0AC06175F for ; Tue, 11 May 2021 03:51:30 -0700 (PDT) Received: by mail-pf1-x429.google.com with SMTP id c17so15793103pfn.6 for ; Tue, 11 May 2021 03:51:30 -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=lGjb9XHs9HEa3yuCIWtdN6OV6aUJlazGyEylQig/2qw=; b=1ZlSDkHHElJFkZnuHviAqONLGrsrF74n1N3r4603t2OcT6B8Zghjytatk5NUDWAMrc CWYBWR0DHY/FIT0z1qEOKkn3++hfRLeyeSa1exRX29IrunIVc2fcFbuABH9vof0rUXHF /D0FIOJckKHayu9vDAtiALygRnnhdSdfAQzTMup39o1wwGXCYbLgZkaitBjY1w7Uu2A3 Iwa73mJ/dlsPt/kwINQkxilRF3wFpWP+ZtWK1/44M7xGUcE9f9IuZbNNkoAJ0sZEnS+C wEfyogG2RhX8rGy/uRAUaZV5pvFsMsHZmUiC44od1xt/PD4GPgUcvi14//naVQmHZgD7 YrWg== 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=lGjb9XHs9HEa3yuCIWtdN6OV6aUJlazGyEylQig/2qw=; b=Jiy/16DqeZ6LqsLDEL7+i2xLmnJcNRLqDSLpvkbK0aryK8Nu07gUslPEg9Gnr2z9p+ p7eQ3nikjoRy2+ckMLCRp5rVi9emQa/SMdzp2UYcecfl0IQpf5E4WzT3YFLYzReVKzPc yIwbWK/mRN6QKeNZz2h5Z/OY1qQ66t8nDSFbCD5yTWJC1BpOTB40upBLTl3sjU4fHrW7 db3D+cI/7ZkcfVlT79hwFGr3J77twS5cCBdMIVeKdcqIYmv+NUJ/Aees8jdPMp3R/mO/ OnP+mmx7R/rklE3GWYoWU5E2xnTcqJpn/6YFvyt6jg7GWzSoOgW0Ifh5sjLJ+I+6CEwz LS5Q== X-Gm-Message-State: AOAM530e9ZiUpMgiHOWXxalTcHNGEYrVlBKZzAlsdde95zcVsw4zzCot 8l7NN7IoVZJQSb7OoQqXG7sXrQ== X-Google-Smtp-Source: ABdhPJwrs5wlHj9JR4nN7o9mNIe/lOSuXtHDeccVzlqFnpwhk46tI6wfm+22UPitRWq14ew6ukG+hg== X-Received: by 2002:a65:5088:: with SMTP id r8mr29061106pgp.12.1620730289556; Tue, 11 May 2021 03:51:29 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.240]) by smtp.gmail.com with ESMTPSA id n18sm13501952pgj.71.2021.05.11.03.51.22 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 May 2021 03:51:29 -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, richard.weiyang@gmail.com, david@fromorbit.com, trond.myklebust@hammerspace.com, anna.schumaker@netapp.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, zhengqi.arch@bytedance.com, duanxiongchun@bytedance.com, fam.zheng@bytedance.com, Muchun Song Subject: [PATCH 02/17] mm: memcontrol: remove kmemcg_id reparenting Date: Tue, 11 May 2021 18:46:32 +0800 Message-Id: <20210511104647.604-3-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210511104647.604-1-songmuchun@bytedance.com> References: <20210511104647.604-1-songmuchun@bytedance.com> MIME-Version: 1.0 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. This already makes 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. It 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);