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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 B09CCC35247 for ; Wed, 5 Feb 2020 22:58:42 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 336E7217BA for ; Wed, 5 Feb 2020 22:58:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 336E7217BA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (unknown [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48CcRz3klNzDqKv for ; Thu, 6 Feb 2020 09:58:39 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.intel.com (client-ip=192.55.52.120; helo=mga04.intel.com; envelope-from=richardw.yang@linux.intel.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.intel.com Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48CcPN4WjgzDqGJ for ; Thu, 6 Feb 2020 09:56:23 +1100 (AEDT) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Feb 2020 14:56:19 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,407,1574150400"; d="scan'208";a="225095649" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga007.fm.intel.com with ESMTP; 05 Feb 2020 14:56:16 -0800 Date: Thu, 6 Feb 2020 06:56:33 +0800 From: Wei Yang To: Baoquan He Subject: Re: [PATCH v6 08/10] mm/memory_hotplug: Don't check for "all holes" in shrink_zone_span() Message-ID: <20200205225633.GA28446@richard> References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-9-david@redhat.com> <20200205095924.GC24162@richard> <20200205144811.GF26758@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200205144811.GF26758@MiWiFi-R3L-srv> User-Agent: Mutt/1.9.4 (2018-02-28) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Wei Yang Cc: linux-s390@vger.kernel.org, x86@kernel.org, linux-ia64@vger.kernel.org, Pavel Tatashin , David Hildenbrand , linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Wei Yang , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Dan Williams , linux-arm-kernel@lists.infradead.org, Oscar Salvador Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Feb 05, 2020 at 10:48:11PM +0800, Baoquan He wrote: >Hi Wei Yang, > >On 02/05/20 at 05:59pm, Wei Yang wrote: >> >diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> >index f294918f7211..8dafa1ba8d9f 100644 >> >--- a/mm/memory_hotplug.c >> >+++ b/mm/memory_hotplug.c >> >@@ -393,6 +393,9 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, >> > if (pfn) { >> > zone->zone_start_pfn = pfn; >> > zone->spanned_pages = zone_end_pfn - pfn; >> >+ } else { >> >+ zone->zone_start_pfn = 0; >> >+ zone->spanned_pages = 0; >> > } >> > } else if (zone_end_pfn == end_pfn) { >> > /* >> >@@ -405,34 +408,11 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, >> > start_pfn); >> > if (pfn) >> > zone->spanned_pages = pfn - zone_start_pfn + 1; >> >+ else { >> >+ zone->zone_start_pfn = 0; >> >+ zone->spanned_pages = 0; >> >+ } >> > } >> >> If it is me, I would like to take out these two similar logic out. > >I also like this style. >> >> For example: >> >> if () { >> } else if () { >> } else { >> goto out; >Here the last else is unnecessary, right? > I am afraid not. If the range is not the first or last, we would leave pfn not initialized. -- Wei Yang Help you, Help me