mm, memcg: pass charge order to oom killer

The oom killer typically displays the allocation order at the time of oom
as a part of its diangostic messages (for global, cpuset, and mempolicy
ooms).

The memory controller may also pass the charge order to the oom killer so
it can emit the same information.  This is useful in determining how large
the memory allocation is that triggered the oom killer.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3728181..bb04067 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1811,7 +1811,7 @@
 /*
  * try to call OOM killer. returns false if we should exit memory-reclaim loop.
  */
-bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask)
+bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
 {
 	struct oom_wait_info owait;
 	bool locked, need_to_kill;
@@ -1841,7 +1841,7 @@
 
 	if (need_to_kill) {
 		finish_wait(&memcg_oom_waitq, &owait.wait);
-		mem_cgroup_out_of_memory(memcg, mask);
+		mem_cgroup_out_of_memory(memcg, mask, order);
 	} else {
 		schedule();
 		finish_wait(&memcg_oom_waitq, &owait.wait);
@@ -2212,7 +2212,7 @@
 	if (!oom_check)
 		return CHARGE_NOMEM;
 	/* check OOM */
-	if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask))
+	if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask, get_order(csize)))
 		return CHARGE_OOM_DIE;
 
 	return CHARGE_RETRY;