From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Date: Tue, 04 Feb 2020 14:42:56 +0000 Subject: Re: [PATCH v6 08/10] mm/memory_hotplug: Don't check for "all holes" in shrink_zone_span() Message-Id: List-Id: References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-9-david@redhat.com> <20200204142516.GD26758@MiWiFi-R3L-srv> In-Reply-To: <20200204142516.GD26758@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Baoquan He 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 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 :) This change at least maintains the same result as before (where the all-holes check would have caught it). -- Thanks, David / dhildenb