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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 BF73BC352A2 for ; Wed, 5 Feb 2020 12:43:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5C59F218AC for ; Wed, 5 Feb 2020 12:43:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WIc0vkYl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5C59F218AC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C086E6B0005; Wed, 5 Feb 2020 07:43:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BBA0E6B0006; Wed, 5 Feb 2020 07:43:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AA7E66B0007; Wed, 5 Feb 2020 07:43:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0058.hostedemail.com [216.40.44.58]) by kanga.kvack.org (Postfix) with ESMTP id 9476A6B0005 for ; Wed, 5 Feb 2020 07:43:44 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5F8583499 for ; Wed, 5 Feb 2020 12:43:44 +0000 (UTC) X-FDA: 76456039968.17.dress95_5ad08c68ba512 X-HE-Tag: dress95_5ad08c68ba512 X-Filterd-Recvd-Size: 4783 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Wed, 5 Feb 2020 12:43:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580906623; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=s7mEVqJKQjbMj0sSKh4xXiDWpaH1dr5EPgu2ctTv8CU=; b=WIc0vkYloQVaE4yPIwInu5iK8slR5G0VhX7sP04FCkMYyP1Dw5DB9vmwMxnhV7DaKRNyzA u513lrNZ0v1MzIlXsTn0hvLsLOrgBZ74ABSji8VvGpxnxPFPfcolpcgf6EiuAeQqrx0WBi L03DA+w9C4e0zvG9BjCJd+MI7d60j3M= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-127-7rVIiLSTMrGSBsygAly1VQ-1; Wed, 05 Feb 2020 07:43:39 -0500 X-MC-Unique: 7rVIiLSTMrGSBsygAly1VQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 22F4185EE6C; Wed, 5 Feb 2020 12:43:36 +0000 (UTC) Received: from localhost (ovpn-12-97.pek2.redhat.com [10.72.12.97]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1F1B681213; Wed, 5 Feb 2020 12:43:32 +0000 (UTC) Date: Wed, 5 Feb 2020 20:43:29 +0800 From: Baoquan He To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, x86@kernel.org, Andrew Morton , Oscar Salvador , Michal Hocko , Pavel Tatashin , Dan Williams , Wei Yang Subject: Re: [PATCH v6 08/10] mm/memory_hotplug: Don't check for "all holes" in shrink_zone_span() Message-ID: <20200205124329.GE26758@MiWiFi-R3L-srv> References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-9-david@redhat.com> <20200204142516.GD26758@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 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 02/04/20 at 03:42pm, David Hildenbrand wrote: > On 04.02.20 15:25, Baoquan He wrote: > > On 10/06/19 at 10:56am, 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 > >> --- > >> 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; > > > > Thinking in which case (zone_start_pfn != start_pfn) and it comes here. > > Could only happen in case the zone_start_pfn would have been "out of the > zone already". If you ask me: unlikely :) Yeah, I also think it's unlikely to come here. The 'if (zone_start_pfn == start_pfn)' checking also covers the case (zone_start_pfn == start_pfn && zone_end_pfn == end_pfn). So this zone_start_pfn/spanned_pages resetting can be removed to avoid confusion.