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 97F50C43331 for ; Sat, 28 Mar 2020 00:27:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4C054206F6 for ; Sat, 28 Mar 2020 00:27:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="VhLwhXOB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C054206F6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F01036B0032; Fri, 27 Mar 2020 20:27:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ED8BD6B0036; Fri, 27 Mar 2020 20:27:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DECFE6B0037; Fri, 27 Mar 2020 20:27:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0039.hostedemail.com [216.40.44.39]) by kanga.kvack.org (Postfix) with ESMTP id C4A8C6B0032 for ; Fri, 27 Mar 2020 20:27:08 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 9906F181AD0A1 for ; Sat, 28 Mar 2020 00:27:08 +0000 (UTC) X-FDA: 76642881336.24.rake58_2138b214f365c X-HE-Tag: rake58_2138b214f365c X-Filterd-Recvd-Size: 4837 Received: from mail-wm1-f65.google.com (mail-wm1-f65.google.com [209.85.128.65]) by imf13.hostedemail.com (Postfix) with ESMTP for ; Sat, 28 Mar 2020 00:27:08 +0000 (UTC) Received: by mail-wm1-f65.google.com with SMTP id g62so14714183wme.1 for ; Fri, 27 Mar 2020 17:27:08 -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=8LHi7DWQnn+e9a15gIK55uU0ddOdIii2CVkZfDdCDGw=; b=VhLwhXOBsuch1bQqvoTgNmV2RgWwgAOiNSPKmjAaqrtJMcSe9NnQE1w4AhXKOoGVBR dX6TP1+ZI17vPScGA2Pwb0GxgVJhC/wpDvI3r/z/uMRnMIj8wTC8cCR0y5mN4X0/kHf4 TEUlKk1xsNssCKrUiQe4p1Uj7VlltSleAeY3SbwkkjC47ZbM1bDPAGT4ReHdqOgzW6Vn 325KKR3X1Er7sMrNq1IVfSVpWKNhVA15Q7MCdUFDP0xkAWFEBE1XEpBLpVUHsnqS36MD b0BsKpWaNn0hlA0iFU0FB5SUMaF71xJKcGcUKL7voeDiIJmkZetcOzKRZFepPjewklA6 n55w== 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=8LHi7DWQnn+e9a15gIK55uU0ddOdIii2CVkZfDdCDGw=; b=r9je2s00sJhkJ/Rh6pzfrsPMZnzZX34487kuNzlbMc2k1QuOJq5sZJ19Upo23HQHWU Uh0PiHTnb7bXg11sRFuVwV7nEuyBQboyc12cWysPuabiL0Qz+OCH2c0QKqG9jRRZwwNx WPYcQxJ62dOZDvBALOIy18HHWhVzxOR/kDax0BsVyGhrrWiaT3Wzr7kweMOqrez9M+qL SfKIPzwlThPMvNenqen/HHHSOGh5kNLm5HxI6Mjm4ZrECKm1XvTPGPMrqLY5hVc6OEUz xsqDwYMuRSFN4ks4mvdAEXtkQiZxPAWEsQK1VSo9FDIMHG56eAAnD+IOwMEZTScPiOkF WWNA== X-Gm-Message-State: ANhLgQ0AOps7qT8yVgazCwlDRIGL1tkCB/BgdTNvgyjxENqbHpoHsz/C tdU9RNYNXsKuwsR/FJPBokE= X-Google-Smtp-Source: ADFU+vtIG7Lc9lszQ0dy68T428hPdPwxI+HkbxJRRrAs84A6Tgz/onIC2eYUhG3xQ14RpiNpkqvQyQ== X-Received: by 2002:a05:600c:2101:: with SMTP id u1mr1339464wml.136.1585355227084; Fri, 27 Mar 2020 17:27:07 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id e5sm10019240wru.92.2020.03.27.17.27.06 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 27 Mar 2020 17:27:06 -0700 (PDT) Date: Sat, 28 Mar 2020 00:27:05 +0000 From: Wei Yang To: Jason Gunthorpe Cc: John Hubbard , Wei Yang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@redhat.com Subject: Re: [Patch v2 2/2] mm/page_alloc.c: define node_order with all zero Message-ID: <20200328002705.hmo4tikax66o7zo3@master> Reply-To: Wei Yang References: <20200327220121.27823-1-richard.weiyang@gmail.com> <20200327220121.27823-2-richard.weiyang@gmail.com> <4c9d8138-d379-810f-64e7-0d018ed019df@nvidia.com> <20200327231820.GA20941@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200327231820.GA20941@ziepe.ca> User-Agent: NeoMutt/20170113 (1.7.2) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Mar 27, 2020 at 08:18:20PM -0300, Jason Gunthorpe wrote: >On Fri, Mar 27, 2020 at 03:37:57PM -0700, John Hubbard wrote: >> On 3/27/20 3:01 PM, Wei Yang wrote: >> > Since we always clear node_order before getting it, 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 dfcf2682ed40..49dd1f25c000 100644 >> > +++ b/mm/page_alloc.c >> > @@ -5585,7 +5585,7 @@ static void build_thisnode_zonelists(pg_data_t *pgdat) >> > static void build_zonelists(pg_data_t *pgdat) >> > { >> > - static int node_order[MAX_NUMNODES]; >> > + static int node_order[MAX_NUMNODES] = {0}; >> >> >> Looks wrong: now the single instance of node_order is initialized just once by >> the compiler. And that means that only the first caller of this function >> gets a zeroed node_order array... > >It is also redundant, all static data is 0 initialized in Linux and >should not be explicitly initialized so it can remain in .bss > Yeah, you are right. I missed the static word. >> > @@ -5595,7 +5595,6 @@ static void build_zonelists(pg_data_t *pgdat) >> > load = nr_online_nodes; >> > prev_node = local_node; >> > - memset(node_order, 0, sizeof(node_order)); >> >> ...and all subsequent callers are left with whatever debris is remaining in >> node_order. So this is not good. > >Indeed > >Jason -- Wei Yang Help you, Help me