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From: Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH stable-only] mm: fix classzone_idx underflow in shrink_zones()
Message-ID: <cf25f1a5-5276-90ea-1eac-f2a2aceffaef@suse.cz>
Date: Tue, 4 Jul 2017 10:45:43 +0200
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To: stable <stable@vger.kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>, Minchan Kim <minchan@kernel.org>, Michal Hocko <mhocko@kernel.org>, linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, Mel Gorman <mgorman@techsingularity.net>

Hi,

I realize this is against the standard stable policy, but I see no other
way, because the mainline accidental fix is part of 34+ patch reclaim
rework, that would be absurd to try to backport into stable. The fix is
a one-liner though.

The bug affects at least 4.4.y, and likely also older stable trees that
backported commit 7bf52fb891b6, which itself was a fix for 3.19 commit
6b4f7799c6a5. You could revert the 7bf52fb891b6 backport, but then 32bit
with highmem might suffer from OOM or thrashing.

More details in the changelog itself.

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