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,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 29D7BC2D0E8 for ; Thu, 26 Mar 2020 22:36:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F286A2077D for ; Thu, 26 Mar 2020 22:36:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="V3sdbZ6C" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727683AbgCZWgG (ORCPT ); Thu, 26 Mar 2020 18:36:06 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:41892 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726067AbgCZWgG (ORCPT ); Thu, 26 Mar 2020 18:36:06 -0400 Received: by mail-qt1-f195.google.com with SMTP id i3so7036739qtv.8 for ; Thu, 26 Mar 2020 15:36:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=jcJBwUc87Jwe+9cOfSIvE+QFlU+cxqdBx8XRklms6k8=; b=V3sdbZ6CxWcM8nunlXYfN3PzwezVfPUPS8L7pO57bgPnlAU91nvRWM8XK+3SPNwiON tnUSf1pbWCI6eUfj02DGKhVs5M/0eK+Jsch78es8S4Jgcwc8DznGYN+VjyIXR6+eionk 6/DDDlO0MLkmCm4mJUJN53NtmX7DTVvEReJ0gZhMbvli1NiAbVknnX/q8JG3uP6RQ6OR x3sK/AeBmf7KIOd/QoO8C5gA4IbLUx/Qq177dfBqTcGhnGey8X3wuC2TH/US4TTkER4S RroXw0XSM5PCgtMg7jesVPWuljoNrMM06/Wr5Y+H/LCdkTBVSsd7EGkDfkKMcn+FJzxA zwqw== 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:references :mime-version:content-disposition:in-reply-to:user-agent; bh=jcJBwUc87Jwe+9cOfSIvE+QFlU+cxqdBx8XRklms6k8=; b=QltEpbGAh0TcmotMHhHJVper+sKOMP9fl++Zrul+6rJVOesmSKF8RUFjPTGI5pjPCr 2OzVarV77gimKaCpI+29OXW6/BPbLWMyBDBqGzJApCa3z2pY5Lz1tmykbLpdpIF3vVtn FFeiNW8HihMUB1uJP0btewk+yxCmSjTlMQR/G/w1h4VWLZxoW1Wt7ecfIr54rNlhKPHZ RPB0OgRrVSUy5Qye9EXWLuAQEDlXMnmYbKIGZioekT2KUr5Xh6mzPV1WIlWOjWB2D9Qp ZIK5lnHpDUEi2yq3fwuQUiLTNThRphGHYxj1wyPlaMyCj5sjSony+8E0d/H9nKsUAwSz X4rg== X-Gm-Message-State: ANhLgQ0XBguyOaQGuKum3gXSe1JFWC1c5mM6Sh7kIiBrs7z392wplaDN fWGkrrqa3ax7oWhQLjzoq083hw== X-Google-Smtp-Source: ADFU+vvN1aO/CdBkNZbFR64XEwxbdEc/AQl3mOpROijPvKW0dCXxErokR05tF2hQt4ClPkC3tqfHPw== X-Received: by 2002:ac8:6697:: with SMTP id d23mr10956191qtp.8.1585262165441; Thu, 26 Mar 2020 15:36:05 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-68-57-212.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.68.57.212]) by smtp.gmail.com with ESMTPSA id m1sm2571690qtm.22.2020.03.26.15.36.04 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 26 Mar 2020 15:36:04 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jHb6a-0003Z0-7r; Thu, 26 Mar 2020 19:36:04 -0300 Date: Thu, 26 Mar 2020 19:36:04 -0300 From: Jason Gunthorpe To: Wei Yang Cc: 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: <20200326223604.GP20941@ziepe.ca> References: <20200326222445.18781-1-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200326222445.18781-1-richard.weiyang@gmail.com> User-Agent: Mutt/1.9.4 (2018-02-28) 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 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. Jason