From patchwork Tue Sep 14 07:28:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 12491879 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 10A36C4332F for ; Tue, 14 Sep 2021 07:33:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E391A61209 for ; Tue, 14 Sep 2021 07:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240691AbhINHfJ (ORCPT ); Tue, 14 Sep 2021 03:35:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240981AbhINHey (ORCPT ); Tue, 14 Sep 2021 03:34:54 -0400 Received: from mail-pl1-x636.google.com (mail-pl1-x636.google.com [IPv6:2607:f8b0:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 091BEC0613C1 for ; Tue, 14 Sep 2021 00:33:31 -0700 (PDT) Received: by mail-pl1-x636.google.com with SMTP id f21so5362054plb.4 for ; Tue, 14 Sep 2021 00:33:31 -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=pdSMr5/T83fWycgKHeCNyglH8dIFjVjgVfZi+3aGb/o=; b=lcF2FdRL9SmDj6sPoOKJRFfCDRkvqUq7bcdi+w6EjU85E25KLBbP9RZIf1g1RF1VGF dYD9vWNLARJj2aso1D0zfM0tnh4+8LLXP8x/ks1iAmoSo5bmlyG8s7Z4L6t/Hzh3kAb5 aiqgfjgCJg0JeYJHrRHvuB3Z0Z7gozQJUUV59v99TdjJn4MNtsOzrrf2X0U15bNWONQM 5+CLF53XPlAE3WN/08ilsg/S9SSdjV5YOvnjHcNrUELXww7m4qHx+z7E74VGqXqULLTE 484Bt5XKw+KSNOZ871DW0obWlvMU3XQsR/zX7L4m/X/CtmizI8nwl5rOukLwJO8Bpky4 qO2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=pdSMr5/T83fWycgKHeCNyglH8dIFjVjgVfZi+3aGb/o=; b=XZPJdLW1hcHC7xoGnnNvgdQ3zQPwZSBFJxDb+IVYZWdw+r9r6ueLM+WbSm2Vv/9I7u s8t9YMSl7TQkDm7W0hLY62HcJCrvshImOtW3kUZ5esp48bUbjJGhfyGnrO4FsvsONhHq vmwaWr7sShS2UHjyp9F0rUKGGVrzHg4Gqkl75ZRT8WxiiW6L5WSuS9NDC8JqlSSNSquD MAv8ZTAyAivURyTHjCCgBJtbspHeWihmc+rW5cXrIImGxqMLP0vmoHP+sBwtaAX2RSkU 7Aq/74omJXf9badnLznWxrA7LukDwOKdKWksP1ywwqPUeRDXy76OSLJABDOP6r+HhofA o8Bw== X-Gm-Message-State: AOAM530tj1mnUTwNkBzLL1M4gBpgmQiViuxvovzDOSYcqqIDpAosue4Q yNzaPgSBHWPuHAZ1ZU60IWmnEw== X-Google-Smtp-Source: ABdhPJyd7C7ap9YT7ZyYr6oDPQ1gvF/rR4tIJydHVVLbWcwDTcRs26m4qzANk3uL3N76KhhkCvYSxA== X-Received: by 2002:a17:90a:1c81:: with SMTP id t1mr544287pjt.170.1631604810566; Tue, 14 Sep 2021 00:33:30 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.244]) by smtp.gmail.com with ESMTPSA id s3sm9377839pfd.188.2021.09.14.00.33.24 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 Sep 2021 00:33:30 -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, smuchun@gmail.com, Muchun Song Subject: [PATCH v3 05/76] mm: list_lru: remove holding lru lock Date: Tue, 14 Sep 2021 15:28:27 +0800 Message-Id: <20210914072938.6440-6-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210914072938.6440-1-songmuchun@bytedance.com> References: <20210914072938.6440-1-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 spin lock can serve as an RCU read-side critical section which already allows readers that hold nlru->lock avoid taking rcu lock. So just to remove holding lock. Signed-off-by: Muchun Song --- mm/list_lru.c | 11 ----------- 1 file changed, 11 deletions(-) diff --git a/mm/list_lru.c b/mm/list_lru.c index 4962d48d4410..6b2f3cbe5f67 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -402,18 +402,7 @@ 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; }