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 <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
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 <osalvador@xxxxxxx>
> ---
> 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
