[PATCH] Fix kswapd spinning

When a zone (usually DMA) has no active pages, pages_scanned (which
triggers all_unreclaimable) is only incremented when scanning the active
list. 

Make sure it's incremented for scanned cache entries too.
Tested-by: Terje Fåberg <terje_fb@yahoo.no>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/vmscan.c

@@ -575,6 +575,7 @@ static void shrink_cache(struct zone *zone, struct scan_control *sc)
 			nr_taken++;
 		}
 		zone->nr_inactive -= nr_taken;
+		zone->pages_scanned += nr_scan;
 		spin_unlock_irq(&zone->lru_lock);
 
 		if (nr_taken == 0)