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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C86ECC2D0EC for ; Fri, 27 Mar 2020 13:27:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F8D92137B for ; Fri, 27 Mar 2020 13:27:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="iZo3Z5/h" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727593AbgC0N10 (ORCPT ); Fri, 27 Mar 2020 09:27:26 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:38869 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726275AbgC0N1Z (ORCPT ); Fri, 27 Mar 2020 09:27:25 -0400 Received: by mail-wr1-f65.google.com with SMTP id s1so11398374wrv.5 for ; Fri, 27 Mar 2020 06:27:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=MiukankS2d7HoYog4uANLr+kARZRnzMZU2xCKuAVLzw=; b=iZo3Z5/hPxxnQ4EWWx1JJmhNk3kYv8xKiaps4ep//w5VyMNqVTuh9PiCjiYvewDmr8 6VWBPsBnNplJbLo/E1nQlQr1VoY6ciX7nxmQ7ml6NNZ6AQFEeTa6c064Hz+uQBkMxIYb wXDJmgh3VB+RmSAHHnDcOHpSMifXRhmaraoK5USGFBHzIQSMwytoEKO3pC0+NhpHsSQj Poh0JDNIB7VKR27DgAuTneNIVNcbC48+wt4FILzJRgYgTlXJoyOrQpnKqqxSSiM40xgW rE/07Esi5tND2/aO3nbkV9omsfklgvrJjI7zPSC9wfb5tpNFqwNldOqwOWMGaRjIDCWj 5+Yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=MiukankS2d7HoYog4uANLr+kARZRnzMZU2xCKuAVLzw=; b=WHCJbbi3NBR+9J5s/MnAVy2jsH3XXxmD7RByerlUtyx3qeVry36BBwJ8yYO//l07Jg ZOU8MQZT+b5SFcJUzM+EjswnpE3Pvp+lgpD61m4XfJB46dtnp0aQOaMTBHRKTDMa2DZR ak+ycmg/oluCae3zZR1WUw4qxKRCcXfUcu/HW8ReYarM3Z6wpjyNVvTEajLmVg0s08Em nDultH/vvQL2udOGLAikO1WKaaCJWEBqQf2sa/bBClo2RCtI5cLXzpStagDYB6nDLCG+ YJpjNY+JQHwlc0mzLbTCL+iwHPu6kqWd/G2XiDPJX+Ftg4ATdfunCMJJWvTYKT4IlxT5 LZ+Q== X-Gm-Message-State: ANhLgQ3FdFdVVsI28JnFnvTg9WWCjrgaQRWkJWmeMoh0I+9qFtBX7odF EziWs2SwwN2iacyVKT4Gf7w= X-Google-Smtp-Source: ADFU+vsnYsTAqeHpcm8tqBofCqi4JBfOXJF5rVRfuLS7F1WUtlA/PE3zXOxs67WjpxoJNi1u4gmHaQ== X-Received: by 2002:adf:f1ce:: with SMTP id z14mr15194886wro.68.1585315643876; Fri, 27 Mar 2020 06:27:23 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id y16sm8334328wrp.78.2020.03.27.06.27.22 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 27 Mar 2020 06:27:23 -0700 (PDT) Date: Fri, 27 Mar 2020 13:27:22 +0000 From: Wei Yang To: Jason Gunthorpe Cc: Wei Yang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] mm/page_alloc.c: leverage compiler to zero out used_mask Message-ID: <20200327132722.rovaz5hghl5vhhl7@master> Reply-To: Wei Yang References: <20200326222445.18781-1-richard.weiyang@gmail.com> <20200326223604.GP20941@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200326223604.GP20941@ziepe.ca> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 26, 2020 at 07:36:04PM -0300, Jason Gunthorpe wrote: >On Thu, Mar 26, 2020 at 10:24:44PM +0000, Wei Yang wrote: >> Since we always clear used_mask before getting node order, we can >> leverage compiler to do this instead of at run time. >> >> Signed-off-by: Wei Yang >> mm/page_alloc.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 0e823bca3f2f..2144b6ceb119 100644 >> +++ b/mm/page_alloc.c >> @@ -5587,14 +5587,13 @@ static void build_zonelists(pg_data_t *pgdat) >> { >> static int node_order[MAX_NUMNODES]; >> int node, load, nr_nodes = 0; >> - nodemask_t used_mask; >> + nodemask_t used_mask = {.bits = {0}}; > >If this style is to be done it should just be '= {}'; > >This case demonstrates why the popular '= {0}' idiom is not such a >good idea, as it only works if the first member is an integral type. > Thanks for your comment. I think David found a better solution. >Jason -- Wei Yang Help you, Help me