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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA7B8C77B6C for ; Thu, 13 Apr 2023 09:07:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229938AbjDMJH2 (ORCPT ); Thu, 13 Apr 2023 05:07:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229787AbjDMJHY (ORCPT ); Thu, 13 Apr 2023 05:07:24 -0400 Received: from mail-lj1-x22a.google.com (mail-lj1-x22a.google.com [IPv6:2a00:1450:4864:20::22a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C6F783F8; Thu, 13 Apr 2023 02:07:14 -0700 (PDT) Received: by mail-lj1-x22a.google.com with SMTP id b33so10352202ljf.2; Thu, 13 Apr 2023 02:07:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1681376833; x=1683968833; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=2nwth3f3dlESn+xcWsI3GV0ApYXXBMlu6d6OTG1ZvlY=; b=KmPbLiqsmMc4cNxb7TG0JMYJLr3RywbCDFSS8PotigkKMUdFMykxLdwdKlh74yvAWY /KYxKqLYp6WujQ15SPk0h5gXaVNCDKf/8kgjas+MxnK4Il6Q5dTN+yQh2YL7VpbQJmhN 7cF+BEZKXbINt7wGyjxEyQL5lBWDqWxLyCd70MBtgWkY3MGxIUXTlmqBtuIjPW72E8Td QZwls6tlVWymzbnRsHHX7SL8c72SFMesKa3tlvtd5QJGz27UDq5ZtI0IjYsIWLOvn9Oj wF9IgvURsb5eSGU8ktr079UdkULuGxk+hBcNZ1fZM0F9yHRoIfBF02np47+kmKeR8kAv zFDQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681376833; x=1683968833; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=2nwth3f3dlESn+xcWsI3GV0ApYXXBMlu6d6OTG1ZvlY=; b=GXkMi5Wrevf2spOMOqQheYBs+Vun2EqfZ56aJa9q3eUyHI7hMh/ci+JQA2PY5oimRX DaYNuUY7mrKxmOL5QWjHTmBl7PYiwIdjSc9L9/h+vSfWRBNYnZ0u0mE0rh7Ihwe2MlPH LiqRGK31b7KoZuZIP79k7W0dtxeID2XwZKuEQxCeXqBwFBZIAajrKikUs6YrD1aaQT92 h4O0aFC7bNq9kDRDM7Us6GIwyPDJMjagy/2P8M1fnbA6PJPhdujX5zNDi5dDx6VG8DsH MQ2migEDFN1tsNixJ2wFPud1+00bNWoWfF8BtPhEUcVmh/lwyZG45tnKLY8K1/VLySM6 XYgg== X-Gm-Message-State: AAQBX9cW9STWuSFVqeCVhxWx2uMSrFRG5sqPd0t9FZm/OpGUszU1CxNN GJb3TKMv2SELUYozo7rKY+s= X-Google-Smtp-Source: AKy350a+d3J2QqMnTyLB5QUmgSNUAYdPm2HwqBrHn2ztoXz2D4gOu7o7YUt8j3COeTRXdLl1WM/PbA== X-Received: by 2002:a2e:301a:0:b0:29b:80b4:7bf7 with SMTP id w26-20020a2e301a000000b0029b80b47bf7mr598325ljw.41.1681376832750; Thu, 13 Apr 2023 02:07:12 -0700 (PDT) Received: from pc636 (host-90-235-5-238.mobileonline.telia.com. [90.235.5.238]) by smtp.gmail.com with ESMTPSA id h13-20020a2e900d000000b002987088bda4sm177565ljg.69.2023.04.13.02.07.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Apr 2023 02:07:12 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Thu, 13 Apr 2023 11:07:09 +0200 To: Zqiang Cc: urezki@gmail.com, paulmck@kernel.org, frederic@kernel.org, joel@joelfernandes.org, qiang.zhang1211@gmail.com, rcu@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rcu/kvfree: Make fill page cache start from krcp->nr_bkv_objs Message-ID: References: <20230412143127.1062367-1-qiang1.zhang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230412143127.1062367-1-qiang1.zhang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 12, 2023 at 10:31:27PM +0800, Zqiang wrote: > The fill_page_cache_func() is invoked and start from zero to > allocate nr_pages of page, if the kfree_rcu_work() executes before > the fill_page_cache_func(), the krcp->nr_bkv_objs is updated before > enter for-loop and equal to nr_pages, since the page is allocated > first, and then check the krcp->nr_bkv_objs in put_cached_bnode(), > this produces a meaningless __get_free_page() call, this commit > therefore make allocate page start from krcp->nr_bkv_objs and > check krcp->nr_bkv_objs before allocate page. > > Signed-off-by: Zqiang > --- > kernel/rcu/tree.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 41daae3239b5..dcb86f9f2dd6 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -3223,7 +3223,7 @@ static void fill_page_cache_func(struct work_struct *work) > nr_pages = atomic_read(&krcp->backoff_page_cache_fill) ? > 1 : rcu_min_cached_objs; > > - for (i = 0; i < nr_pages; i++) { > + for (i = READ_ONCE(krcp->nr_bkv_objs); i < nr_pages; i++) { > bnode = (struct kvfree_rcu_bulk_data *) > __get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); > > -- > 2.32.0 > Reviewed-by: Uladzislau Rezki (Sony) -- Uladzislau Rezki