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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 BAA20C2D0B1 for ; Tue, 4 Feb 2020 09:17:15 +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 75B212087E for ; Tue, 4 Feb 2020 09:17:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 75B212087E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de 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 (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48BfGd3PKyzDqFF for ; Tue, 4 Feb 2020 20:17:13 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=suse.de (client-ip=195.135.220.15; helo=mx2.suse.de; envelope-from=osalvador@suse.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=suse.de Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (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 48BfB931mfzDqLH for ; Tue, 4 Feb 2020 20:13:21 +1100 (AEDT) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id A8FB2B020; Tue, 4 Feb 2020 09:13:15 +0000 (UTC) Date: Tue, 4 Feb 2020 10:13:12 +0100 From: Oscar Salvador To: David Hildenbrand Subject: Re: [PATCH v6 08/10] mm/memory_hotplug: Don't check for "all holes" in shrink_zone_span() Message-ID: <20200204091312.GC6494@linux> References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-9-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191006085646.5768-9-david@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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: , Cc: linux-s390@vger.kernel.org, Michal Hocko , linux-ia64@vger.kernel.org, Pavel Tatashin , linux-sh@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Wei Yang , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Dan Williams , linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sun, Oct 06, 2019 at 10:56:44AM +0200, David Hildenbrand wrote: > If we have holes, the holes will automatically get detected and removed > once we remove the next bigger/smaller section. The extra checks can > go. > > Cc: Andrew Morton > Cc: Oscar Salvador > Cc: Michal Hocko > Cc: David Hildenbrand > Cc: Pavel Tatashin > Cc: Dan Williams > Cc: Wei Yang > Signed-off-by: David Hildenbrand Heh, I have been here before. I have to confess that when I wrote my version of this I was not really 100% about removing it, because hotplug was a sort of a "catchall" for all sort of weird and corner-cases configurations, but thinking more about it, I cannot think of any situation that would make this blow up. Reviewed-by: Oscar Salvador > --- > mm/memory_hotplug.c | 34 +++++++--------------------------- > 1 file changed, 7 insertions(+), 27 deletions(-) > > 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; > + } > } > - > - /* > - * The section is not biggest or smallest mem_section in the zone, it > - * only creates a hole in the zone. So in this case, we need not > - * change the zone. But perhaps, the zone has only hole data. Thus > - * it check the zone has only hole or not. > - */ > - pfn = zone_start_pfn; > - for (; pfn < zone_end_pfn; pfn += PAGES_PER_SUBSECTION) { > - if (unlikely(!pfn_to_online_page(pfn))) > - continue; > - > - if (page_zone(pfn_to_page(pfn)) != zone) > - continue; > - > - /* Skip range to be removed */ > - if (pfn >= start_pfn && pfn < end_pfn) > - continue; > - > - /* If we find valid section, we have nothing to do */ > - zone_span_writeunlock(zone); > - return; > - } > - > - /* The zone has no valid section */ > - zone->zone_start_pfn = 0; > - zone->spanned_pages = 0; > zone_span_writeunlock(zone); > } > > -- > 2.21.0 > -- Oscar Salvador SUSE L3