Re: [PATCH 11/14] mm, memory_hotplug: do not associate hotadded memory to zones until online

From: Michal Hocko
Date: Mon Jun 26 2017 - 01:38:44 EST


On Sun 25-06-17 08:14:13, Wei Yang wrote:
> On Mon, May 15, 2017 at 10:58:24AM +0200, Michal Hocko wrote:
> >From: Michal Hocko <mhocko@xxxxxxxx>
> >
> [...]
> >+void move_pfn_range_to_zone(struct zone *zone,
> >+ unsigned long start_pfn, unsigned long nr_pages)
> >+{
> >+ struct pglist_data *pgdat = zone->zone_pgdat;
> >+ int nid = pgdat->node_id;
> >+ unsigned long flags;
> >+ unsigned long i;
>
> This is an unused variable:
>
> mm/memory_hotplug.c: In function âmove_pfn_range_to_zoneâ:
> mm/memory_hotplug.c:895:16: warning: unused variable âiâ [-Wunused-variable]
>
> Do you suggest me to write a patch or you would fix it in your later rework?

Please send a fix for your
http://lkml.kernel.org/r/20170616092335.5177-2-richard.weiyang@xxxxxxxxx
Andrew will fold it into that patch.

>
> >+
> >+ if (zone_is_empty(zone))
> >+ init_currently_empty_zone(zone, start_pfn, nr_pages);
> >+
> >+ clear_zone_contiguous(zone);
> >+
> >+ /* TODO Huh pgdat is irqsave while zone is not. It used to be like that before */
> >+ pgdat_resize_lock(pgdat, &flags);
> >+ zone_span_writelock(zone);
> >+ resize_zone_range(zone, start_pfn, nr_pages);
> >+ zone_span_writeunlock(zone);
> >+ resize_pgdat_range(pgdat, start_pfn, nr_pages);
> >+ pgdat_resize_unlock(pgdat, &flags);
> >+
> >+ /*
> >+ * TODO now we have a visible range of pages which are not associated
> >+ * with their zone properly. Not nice but set_pfnblock_flags_mask
> >+ * expects the zone spans the pfn range. All the pages in the range
> >+ * are reserved so nobody should be touching them so we should be safe
> >+ */
> >+ memmap_init_zone(nr_pages, nid, zone_idx(zone), start_pfn, MEMMAP_HOTPLUG);
> >+ for (i = 0; i < nr_pages; i++) {
> >+ unsigned long pfn = start_pfn + i;
> >+ set_page_links(pfn_to_page(pfn), zone_idx(zone), nid, pfn);
> > }
> >
> >2.11.0
>
> --
> Wei Yang
> Help you, Help me



--
Michal Hocko
SUSE Labs