[BUGFIX][PATCH 3/4] mecg: fix oom flag at THP charge

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Thanks to Johanns and Daisuke for suggestion.
=
Hugepage allocation shouldn't trigger oom.
Allocation failure is not fatal.

Orignal-patch-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 mm/memcontrol.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: mmotm-0125/mm/memcontrol.c
===================================================================
--- mmotm-0125.orig/mm/memcontrol.c
+++ mmotm-0125/mm/memcontrol.c
@@ -2369,11 +2369,14 @@ static int mem_cgroup_charge_common(stru
 	struct page_cgroup *pc;
 	int ret;
 	int page_size = PAGE_SIZE;
+	bool oom;
 
 	if (PageTransHuge(page)) {
 		page_size <<= compound_order(page);
 		VM_BUG_ON(!PageTransHuge(page));
-	}
+		oom = false;
+	} else
+		oom = true;
 
 	pc = lookup_page_cgroup(page);
 	/* can happen at boot */
@@ -2381,7 +2384,7 @@ static int mem_cgroup_charge_common(stru
 		return 0;
 	prefetchw(pc);
 
-	ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true, page_size);
+	ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, oom, page_size);
 	if (ret || !mem)
 		return ret;