[patch 3/3] memcg: never OOM when charging huge pages

[Johannes Weiner <hannes@cmpxchg.org>]

Huge page coverage should obviously have less priority than the
continued execution of a process.

Never kill a process when charging it a huge page fails.  Instead,
give up after the first failed reclaim attempt and fall back to
regular pages.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 17c4e36..2945649 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1890,6 +1890,13 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
 	int csize = max(CHARGE_SIZE, (unsigned long) page_size);
 
 	/*
+	 * Do not OOM on huge pages.  Fall back to regular pages after
+	 * the first failed reclaim attempt.
+	 */
+	if (page_size > PAGE_SIZE)
+		oom = false;
+
+	/*
 	 * Unlike gloval-vm's OOM-kill, we're not in memory shortage
 	 * in system level. So, allow to go ahead dying process in addition to
 	 * MEMDIE process.
-- 
1.7.3.5

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