From: David Hildenbrand <david@xxxxxxxxxx> Subject: mm/memory_hotplug: don't check for "all holes" in shrink_zone_span() 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. Link: http://lkml.kernel.org/r/20191006085646.5768-9-david@xxxxxxxxxx Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx> Cc: Oscar Salvador <osalvador@xxxxxxx> Cc: Pankaj Gupta <pagupta@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory_hotplug.c | 34 +++++++--------------------------- 1 file changed, 7 insertions(+), 27 deletions(-) --- a/mm/memory_hotplug.c~mm-memory_hotplug-dont-check-for-all-holes-in-shrink_zone_span +++ a/mm/memory_hotplug.c @@ -411,6 +411,9 @@ static void shrink_zone_span(struct zone 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) { /* @@ -423,34 +426,11 @@ static void shrink_zone_span(struct zone 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); } _
