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Date: Fri, 31 Mar 2017 08:50:02 +0200
From: Michal Hocko <mhocko@kernel.org>
To: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: linux-mm@kvack.org, "'Andrew Morton'" <akpm@linux-foundation.org>,
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Subject: Re: [PATCH 5/6] mm, memory_hotplug: do not associate hotadded memory
 to zones until online
Message-ID: <20170331065002.GD27098@dhcp22.suse.cz>
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On Fri 31-03-17 14:18:08, Hillf Danton wrote:
> 
> On March 30, 2017 7:55 PM Michal Hocko wrote:
> > 
> > +static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
> > +		unsigned long nr_pages)
> > +{
> > +	unsigned long old_end_pfn = zone_end_pfn(zone);
> > +
> > +	if (start_pfn < zone->zone_start_pfn)
> > +		zone->zone_start_pfn = start_pfn;
> > +
> > +	zone->spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - zone->zone_start_pfn;
> > +}
> The implementation above implies zone can only go bigger.

yes, we do not shrink zones currently and I see no poit in doing that
right now.

> Can we resize zone with the given data?

Why couldn't we?

-- 
Michal Hocko
SUSE Labs