Just nitpicking, but:

On Tue, Feb 5, 2013 at 3:57 AM, Mel Gorman [off-list ref] wrote:

+static inline bool zone_is_idx(struct zone *zone, enum zone_type idx)
+{
+       /* This mess avoids a potentially expensive pointer subtraction. */
+       int zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones;
+       return zone_off == idx * sizeof(*zone);
+}

Maybe:
return zone == zone->zone_pgdat->node_zones + idx;
?

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.

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