mm: memcontrol: reclaim when shrinking memory.high below usage

mm: memcontrol: reclaim when shrinking memory.high below usage

Orabug: 23331124

[ Upstream commit 588083bb37a3cea8533c392370a554417c8f29cb ]

When setting memory.high below usage, nothing happens until the next
charge comes along, and then it will only reclaim its own charge and not
the now potentially huge excess of the new memory.high.  This can cause
groups to stay in excess of their memory.high indefinitely.

To fix that, when shrinking memory.high, kick off a reclaim cycle that
goes after the delta.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 62b3bd2a4f98852cefd0df17333362638246aa8f)

Signed-off-by: Dan Duval <dan.duval@oracle.com>