From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov@parallels.com>,
        Vlastimil Babka <vbabka@suse.cz>, Mel Gorman <mgorman@suse.de>,
        <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 0/2] 2 zone_pages_reclaimable fixes
Date: Tue, 24 Nov 2015 12:54:58 +0100
Message-Id: <1448366100-11023-1-git-send-email-mhocko@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1034
Lines: 20

Hi,
Johannes had a valid point [1] that zone_pages_reclaimable should contain
isolated pages as well. This is what the first patch does. While I was
there I've realized that the current logic of this function allows for
a large overestimation of the reclaimable memory with anon >> nr_swap_pages
which would be visible especially when the swap is getting short on space.
I think this is a bug and this is fixed in the second patch.

I do not have any particular workload which would show significant misbehavior
because of the current implementation though. We mostly just happen to scan
longer than necessary because zone_reclaimable would keep us looping longer
but I still think it makes sense to fix this regardless.

[1] http://lkml.kernel.org/r/20151123182447.GF13000%40cmpxchg.org

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