mm: remove seemingly spurious reclaimability check from laptop_mode gating

Commit 1d82de61 ("mm, vmscan: make kswapd reclaim in terms of
nodes") allowed laptop_mode=1 to start writing not just when the
priority drops to DEF_PRIORITY - 2 but also when the node is
unreclaimable.

That appears to be a spurious change in this patch as I doubt the series
was tested with laptop_mode, and neither is that particular change
mentioned in the changelog.  Remove it, it's still recent.

Link: http://lkml.kernel.org/r/20170228214007.5621-4-hannes@cmpxchg.orgSigned-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmscan.c

@@ -3285,7 +3285,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 		 * If we're getting trouble reclaiming, start doing writepage
 		 * even in laptop mode.
 		 */
-		if (sc.priority < DEF_PRIORITY - 2 || !pgdat_reclaimable(pgdat))
+		if (sc.priority < DEF_PRIORITY - 2)
 			sc.may_writepage = 1;
 
 		/* Call soft limit reclaim before calling shrink_node. */