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Wed, 05 Feb 2020 08:34:53 -0500 X-MC-Unique: zh-m8MZxM7-EvXc2VHf3tA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D1C3C8018A6; Wed, 5 Feb 2020 13:34:50 +0000 (UTC) Received: from localhost (ovpn-12-97.pek2.redhat.com [10.72.12.97]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6566C101D481; Wed, 5 Feb 2020 13:34:45 +0000 (UTC) Date: Wed, 5 Feb 2020 21:34:42 +0800 From: Baoquan He To: David Hildenbrand Subject: Re: [PATCH v6 08/10] mm/memory_hotplug: Don't check for "all holes" in shrink_zone_span() Message-ID: <20200205133442.GC8965@MiWiFi-R3L-srv> References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-9-david@redhat.com> <20200204142516.GD26758@MiWiFi-R3L-srv> <20200205124329.GE26758@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200205_053459_679220_9CD79C68 X-CRM114-Status: GOOD ( 21.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: 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, Oscar Salvador Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 02/05/20 at 02:20pm, David Hildenbrand wrote: > On 05.02.20 13:43, Baoquan He wrote: > > 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. > > At least I would find it more confusing without it (or want a comment > explaining why this does not have to be handled and why the !pfn case is > not possible). I don't get why being w/o it will be more confusing, but it's OK since it doesn't impact anything. > > Anyhow, that patch is already upstream and I don't consider this high > priority. Thanks :) Yeah, noticed you told Wei the status in another patch thread, I am fine with it, just leave it to you to decide. Thanks. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel