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>

4 files changed, 18 insertions, 25 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 2a80544aec99..5a3ee6423634 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -180,8 +180,6 @@ static inline void mem_cgroup_dec_page_stat(struct page *page,
 unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
                                                 gfp_t gfp_mask,
                                                 unsigned long *total_scanned);
-extern void __mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
-                                       int order);
 
 void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 5dc0e384ae9e..49a3031fda50 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -61,6 +61,9 @@ extern void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
 extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
 
+extern void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
+                               int order, const nodemask_t *nodemask);
+
 extern enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
                 unsigned long totalpages, const nodemask_t *nodemask,
                 bool force_kill);
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;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index a3a32ae02e9d..198600861638 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -556,8 +556,8 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 /*
  * Determines whether the kernel must panic because of the panic_on_oom sysctl.
  */
-static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
-                                int order, const nodemask_t *nodemask)
+void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
+                        int order, const nodemask_t *nodemask)
 {
         if (likely(!sysctl_panic_on_oom))
                 return;
@@ -575,25 +575,6 @@ static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
                 sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
 }
 
-#ifdef CONFIG_MEMCG
-void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
-                              int order)
-{
-        /*
-         * 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);
-        __mem_cgroup_out_of_memory(memcg, gfp_mask, order);
-}
-#endif
-
 static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
 
 int register_oom_notifier(struct notifier_block *nb)