1 files changed, 29 insertions, 11 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 6f6e04c40c9..7c8488f6a3f 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -362,10 +362,10 @@ static void dump_tasks(const struct mem_cgroup *mem)
 static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
                                                         struct mem_cgroup *mem)
 {
+        task_lock(current);
         pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
                 "oom_adj=%d\n",
                 current->comm, gfp_mask, order, current->signal->oom_adj);
-        task_lock(current);
         cpuset_print_task_mems_allowed(current);
         task_unlock(current);
         dump_stack();
@@ -436,8 +436,11 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
                             unsigned long points, struct mem_cgroup *mem,
                             const char *message)
 {
-        struct task_struct *c;
+        struct task_struct *victim = p;
+        struct task_struct *child;
         struct task_struct *t = p;
+        unsigned long victim_points = 0;
+        struct timespec uptime;
 
         if (printk_ratelimit())
                 dump_header(p, gfp_mask, order, mem);
@@ -451,22 +454,37 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
                 return 0;
         }
 
-        printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n",
-                                        message, task_pid_nr(p), p->comm, points);
+        task_lock(p);
+        pr_err("%s: Kill process %d (%s) score %lu or sacrifice child\n",
+                message, task_pid_nr(p), p->comm, points);
+        task_unlock(p);
 
-        /* Try to kill a child first */
+        /*
+         * If any of p's children has a different mm and is eligible for kill,
+         * the one with the highest badness() score is sacrificed for its
+         * parent.  This attempts to lose the minimal amount of work done while
+         * still freeing memory.
+         */
+        do_posix_clock_monotonic_gettime(&uptime);
         do {
-                list_for_each_entry(c, &t->children, sibling) {
-                        if (c->mm == p->mm)
+                list_for_each_entry(child, &t->children, sibling) {
+                        unsigned long child_points;
+
+                        if (child->mm == p->mm)
                                 continue;
-                        if (mem && !task_in_mem_cgroup(c, mem))
+                        if (mem && !task_in_mem_cgroup(child, mem))
                                 continue;
-                        if (!oom_kill_task(c))
-                                return 0;
+
+                        /* badness() returns 0 if the thread is unkillable */
+                        child_points = badness(child, uptime.tv_sec);
+                        if (child_points > victim_points) {
+                                victim = child;
+                                victim_points = child_points;
+                        }
                 }
         } while_each_thread(p, t);
 
-        return oom_kill_task(p);
+        return oom_kill_task(victim);
 }
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR