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Date: Sat, 16 Jul 2016 00:50:53 +0900
From: Minchan Kim <minchan@kernel.org>
To: Mel Gorman <mgorman@techsingularity.net>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Vlastimil Babka <vbabka@suse.cz>,
        Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/5] mm, vmscan: avoid passing in classzone_idx
 unnecessarily to compaction_ready -fix
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On Fri, Jul 15, 2016 at 02:09:22PM +0100, Mel Gorman wrote:
> As pointed out by Vlastimil, there is a redundant check in shrink_zones
> since commit "mm, vmscan: avoid passing in classzone_idx unnecessarily to
> compaction_ready".  The zonelist iterator only returns zones that already
> meet the requirements of the allocation request.
> 
> This is a fix to the mmotm patch
> mm-vmscan-avoid-passing-in-classzone_idx-unnecessarily-to-compaction_ready.patch
> 
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Minchan Kim <minchan@kernel.org>

Just a Nit:
It seems there is another redundant check in there.

shrink_zones
..
        for_each_zone_zonelist_nodemask(zone, z, zonelist,
                                        sc->reclaim_idx, sc->nodemask) {
                if (!populated_zone(zone)) <==
                        continue;

Of course, it's not your fault but it would be a good chance to
remove such trivial thing :)
If I don't miss something, I hope piggyback on this patch. Andrew?