Re: [PATCH v9 3/8] mm,memory_hotplug: Factor out adjusting present pages into adjust_present_page_count()

Michal Hocko
2021-04-20T09:46:01Z

On Fri 16-04-21 13:24:06, Oscar Salvador wrote:
> From: David Hildenbrand <david@redhat.com>
>
> Let's have a single place (inspired by adjust_managed_page_count()) where
> we adjust present pages.
> In contrast to adjust_managed_page_count(), only memory onlining/offlining
> is allowed to modify the number of present pages.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> Reviewed-by: Oscar Salvador <osalvador@suse.de>

Not sure self review counts ;)

Acked-by: Michal Hocko <mhocko@suse.com>

Btw. I strongly suspect the resize lock is quite pointless here.
Something for a follow up patch.

> ---
> mm/memory_hotplug.c | 22 ++++++++++++----------
> 1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 25e59d5dc13c..d05056b3c173 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -829,6 +829,16 @@ struct zone * zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
> return default_zone_for_pfn(nid, start_pfn, nr_pages);
> }
>
> +static void adjust_present_page_count(struct zone *zone, long nr_pages)
> +{
> + unsigned long flags;
> +
> + zone->present_pages += nr_pages;
> + pgdat_resize_lock(zone->zone_pgdat, &flags);
> + zone->zone_pgdat->node_present_pages += nr_pages;
> + pgdat_resize_unlock(zone->zone_pgdat, &flags);
> +}
> +
> int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
> int online_type, int nid)
> {
> @@ -882,11 +892,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
> }
>
> online_pages_range(pfn, nr_pages);
> - zone->present_pages += nr_pages;
> -
> - pgdat_resize_lock(zone->zone_pgdat, &flags);
> - zone->zone_pgdat->node_present_pages += nr_pages;
> - pgdat_resize_unlock(zone->zone_pgdat, &flags);
> + adjust_present_page_count(zone, nr_pages);
>
> node_states_set_node(nid, &arg);
> if (need_zonelists_rebuild)
> @@ -1701,11 +1707,7 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
>
> /* removal success */
> adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
> - zone->present_pages -= nr_pages;
> -
> - pgdat_resize_lock(zone->zone_pgdat, &flags);
> - zone->zone_pgdat->node_present_pages -= nr_pages;
> - pgdat_resize_unlock(zone->zone_pgdat, &flags);
> + adjust_present_page_count(zone, -nr_pages);
>
> init_per_zone_wmark_min();
>
> --
> 2.16.3

--
Michal Hocko
SUSE Labs