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Date: Fri, 16 Jun 2017 10:05:02 +0200
From: Michal Hocko <mhocko@kernel.org>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
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Subject: Re: [PATCH 11/14] mm, memory_hotplug: do not associate hotadded
 memory to zones until online
Message-ID: <20170616080502.GA30580@dhcp22.suse.cz>
References: <20170515085827.16474-1-mhocko@kernel.org>
 <20170515085827.16474-12-mhocko@kernel.org>
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[Please try to trim the context you are replying to]

On Fri 16-06-17 12:20:58, Wei Yang wrote:
> On Mon, May 15, 2017 at 10:58:24AM +0200, Michal Hocko wrote:
[...]
> > /*
> >+ * Return true if [start_pfn, start_pfn + nr_pages) range has a non-empty
> >+ * intersection with the given zone
> >+ */
> >+static inline bool zone_intersects(struct zone *zone,
> >+		unsigned long start_pfn, unsigned long nr_pages)
> >+{
> >+	if (zone_is_empty(zone))
> >+		return false;
> >+	if (start_pfn >= zone_end_pfn(zone))
> >+		return false;
> >+
> >+	if (zone->zone_start_pfn <= start_pfn)
> >+		return true;
> >+	if (start_pfn + nr_pages > zone->zone_start_pfn)
> >+		return true;
> >+
> >+	return false;
> >+}
> 
> I think this could be simplified as:
> 
> static inline bool zone_intersects(struct zone *zone,
> 		unsigned long start_pfn, unsigned long nr_pages)
> {
> 	if (zone_is_empty(zone))
> 		return false;
> 
> 	if (start_pfn >= zone_end_pfn(zone) ||
> 	    start_pfn + nr_pages <= zone->zone_start_pfn)
> 		return false;
> 
> 	return true;
> }

Feel free to send a patch.
-- 
Michal Hocko
SUSE Labs