From patchwork Thu May 27 06:21:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12283403 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=-16.7 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 631BFC4708B for ; Thu, 27 May 2021 06:25:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 469F9610CC for ; Thu, 27 May 2021 06:25:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234773AbhE0G0d (ORCPT ); Thu, 27 May 2021 02:26:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234803AbhE0G00 (ORCPT ); Thu, 27 May 2021 02:26:26 -0400 Received: from mail-pf1-x435.google.com (mail-pf1-x435.google.com [IPv6:2607:f8b0:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F786C061761 for ; Wed, 26 May 2021 23:24:53 -0700 (PDT) Received: by mail-pf1-x435.google.com with SMTP id g18so2871851pfr.2 for ; Wed, 26 May 2021 23:24:53 -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=4Skb3PkDwb/3WBbW5QytVqXcn8HE8kv5ZTlpyL+++g4=; b=0i7WfGFj/SwesZLMTohEbH+Evib1sQbS+c7e0TNLaQ9zFvhes7YR7vBubu1DEN7o65 U4kaKhsu0ps7yC0WmKlbpnH0Yp1uTp7xsDGZtgw9mvOCUbAxovpLxfdgb1Un1HEs1kD6 vPZkVvlpwqjulQqgd6Lx6rRF9WdZktw/surrmqDbPHFe0cmXZ97ypZ4oLDN8fzh2IxHc 48ovLGD59G7RK+b3/KI/CpYUUsU53ThIfbrik6hoygjAJR2Eib6bSSH51q+9wJb/G0ql 37NfnccShXUqf+ftAHTWbtj9kN/fR4pwwzGjRik/DodaikwAh5Ue66hT25q3+VkSQG3k 6asQ== 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=4Skb3PkDwb/3WBbW5QytVqXcn8HE8kv5ZTlpyL+++g4=; b=Ub6vqCqg1bU7YV2Vi4+xxEi7rzT0NCfJUF/M/1ypZnWYPz+uOe6CJJYzlRgK5iCH2j JYhrWyRcch9EItVylm0iDQxuHbaLe1mxaBtSbjStCRTbLfJ5pZgrLFCIaBDFU6mUdt0S s23dZIBMyn5KTNmXxCx1SX+9W4b5IzSN9vfN0kwgfuPq/K5MO6xl38mRClmmIN33tT1H 915s3QrY4sflRCLNzi/SWUNDcXkwMJAsUu6Axti1BY5ruaFQ4zvmtHLePCtQguFKFUBr hzwK+MPUVEdqjsfgh16XRcHzCvAByOXywQRFnYiefIN7BnHXloRZw/6wc50ul6YrDvZ2 w1Cg== X-Gm-Message-State: AOAM5334xb5E8kIZ+t2qoRYyp1O84xtT5rKiP7FLcROVI2yitdJzlmZ1 MWyie8gwOWf+3/NcdRwK9O0dWg== X-Google-Smtp-Source: ABdhPJw32otAEAGQ7wbA7Yy6KLbhe+rjlxJYa8gEkHEt45un6/ZtOcrGlPaiuyYswbLoNoB4qg5JRg== X-Received: by 2002:a63:b243:: with SMTP id t3mr2257632pgo.253.1622096692910; Wed, 26 May 2021 23:24:52 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.254]) by smtp.gmail.com with ESMTPSA id m5sm882971pgl.75.2021.05.26.23.24.43 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 May 2021 23:24:52 -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 v2 05/21] mm: list_lru: remove lru node locking from memcg_update_list_lru_node Date: Thu, 27 May 2021 14:21:32 +0800 Message-Id: <20210527062148.9361-6-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210527062148.9361-1-songmuchun@bytedance.com> References: <20210527062148.9361-1-songmuchun@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Since commit e5bc3af7734f ("rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu()"), the critical section of spinlock can serve as RCU read-side critical section. So we can remove the locking from memcg_update_list_lru_node(). Signed-off-by: Muchun Song --- mm/list_lru.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/mm/list_lru.c b/mm/list_lru.c index 4962d48d4410..e86d4d055d3c 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -403,18 +403,9 @@ static int memcg_update_list_lru_node(struct list_lru_node *nlru, memcpy(&new->lru, &old->lru, old_size * sizeof(void *)); - /* - * The locking below allows readers that hold nlru->lock avoid taking - * rcu_read_lock (see list_lru_from_memcg_idx). - * - * Since list_lru_{add,del} may be called under an IRQ-safe lock, - * we have to use IRQ-safe primitives here to avoid deadlock. - */ - spin_lock_irq(&nlru->lock); rcu_assign_pointer(nlru->memcg_lrus, new); - spin_unlock_irq(&nlru->lock); - kvfree_rcu(old, rcu); + return 0; }