mm, memcg: move all oom handling to memcontrol.c

By globally defining check_panic_on_oom(), the memcg oom handler can be
moved entirely to mm/memcontrol.c.  This removes the ugly #ifdef in the
oom killer and cleans up the code.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 2 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 77a29cea5d76..0f692a2dbfcb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1469,8 +1469,8 @@ static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
         return min(limit, memsw);
 }
 
-void __mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
-                                int order)
+void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
+                              int order)
 {
         struct mem_cgroup *iter;
         unsigned long chosen_points = 0;
@@ -1478,6 +1478,17 @@ void __mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
         unsigned int points = 0;
         struct task_struct *chosen = NULL;
 
+        /*
+         * If current has a pending SIGKILL, then automatically select it.  The
+         * goal is to allow it to allocate so that it may quickly exit and free
+         * its memory.
+         */
+        if (fatal_signal_pending(current)) {
+                set_thread_flag(TIF_MEMDIE);
+                return;
+        }
+
+        check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL);
         totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1;
         for_each_mem_cgroup_tree(iter, memcg) {
                 struct cgroup *cgroup = iter->css.cgroup;