oom: fold __out_of_memory into out_of_memory

__out_of_memory() only has a single caller, so fold it into
out_of_memory() and add a comment about locking for its call to
oom_kill_process().

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: 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, 29 insertions, 36 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index cba18c06e50..26ae6975fa3 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -628,41 +628,6 @@ static void clear_system_oom(void)
         spin_unlock(&zone_scan_lock);
 }
 
-
-/*
- * Must be called with tasklist_lock held for read.
- */
-static void __out_of_memory(gfp_t gfp_mask, int order, const nodemask_t *mask)
-{
-        struct task_struct *p;
-        unsigned long points;
-
-        if (sysctl_oom_kill_allocating_task)
-                if (!oom_kill_process(current, gfp_mask, order, 0, NULL,
-                                "Out of memory (oom_kill_allocating_task)"))
-                        return;
-retry:
-        /*
-         * Rambo mode: Shoot down a process and hope it solves whatever
-         * issues we may have.
-         */
-        p = select_bad_process(&points, NULL, mask);
-
-        if (PTR_ERR(p) == -1UL)
-                return;
-
-        /* Found nothing?!?! Either we hang forever, or we panic. */
-        if (!p) {
-                dump_header(NULL, gfp_mask, order, NULL);
-                read_unlock(&tasklist_lock);
-                panic("Out of memory and no killable processes...\n");
-        }
-
-        if (oom_kill_process(p, gfp_mask, order, points, NULL,
-                             "Out of memory"))
-                goto retry;
-}
-
 /**
  * out_of_memory - kill the "best" process when we run out of memory
  * @zonelist: zonelist pointer
@@ -678,7 +643,9 @@ retry:
 void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
                 int order, nodemask_t *nodemask)
 {
+        struct task_struct *p;
         unsigned long freed = 0;
+        unsigned long points;
         enum oom_constraint constraint = CONSTRAINT_NONE;
 
         blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
@@ -703,10 +670,36 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
         if (zonelist)
                 constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
         check_panic_on_oom(constraint, gfp_mask, order);
+
         read_lock(&tasklist_lock);
-        __out_of_memory(gfp_mask, order,
+        if (sysctl_oom_kill_allocating_task) {
+                /*
+                 * oom_kill_process() needs tasklist_lock held.  If it returns
+                 * non-zero, current could not be killed so we must fallback to
+                 * the tasklist scan.
+                 */
+                if (!oom_kill_process(current, gfp_mask, order, 0, NULL,
+                                "Out of memory (oom_kill_allocating_task)"))
+                        return;
+        }
+
+retry:
+        p = select_bad_process(&points, NULL,
                         constraint == CONSTRAINT_MEMORY_POLICY ? nodemask :
                                                                  NULL);
+        if (PTR_ERR(p) == -1UL)
+                return;
+
+        /* Found nothing?!?! Either we hang forever, or we panic. */
+        if (!p) {
+                dump_header(NULL, gfp_mask, order, NULL);
+                read_unlock(&tasklist_lock);
+                panic("Out of memory and no killable processes...\n");
+        }
+
+        if (oom_kill_process(p, gfp_mask, order, points, NULL,
+                             "Out of memory"))
+                goto retry;
         read_unlock(&tasklist_lock);
 
         /*