writeback: Fix performance regression in wb_over_bg_thresh()

[deliverable/linux.git] / mm / oom_kill.c

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 1a21819a8e5ed6588a31928e674733057519f5ef..b34d279a7ee6c43cb5e85d7e35956159c656cc47 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -419,7 +419,7 @@ bool oom_killer_disabled __read_mostly;
  */
 static struct task_struct *oom_reaper_th;
 static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);
-static LIST_HEAD(oom_reaper_list);
+static struct task_struct *oom_reaper_list;
 static DEFINE_SPINLOCK(oom_reaper_lock);
 
 
@@ -525,16 +525,16 @@ static void oom_reap_task(struct task_struct *tsk)
 
 static int oom_reaper(void *unused)
 {
+       set_freezable();
+
        while (true) {
                struct task_struct *tsk = NULL;
 
-               wait_event_freezable(oom_reaper_wait,
-                                    (!list_empty(&oom_reaper_list)));
+               wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL);
                spin_lock(&oom_reaper_lock);
-               if (!list_empty(&oom_reaper_list)) {
-                       tsk = list_first_entry(&oom_reaper_list,
-                                       struct task_struct, oom_reaper_list);
-                       list_del(&tsk->oom_reaper_list);
+               if (oom_reaper_list != NULL) {
+                       tsk = oom_reaper_list;
+                       oom_reaper_list = tsk->oom_reaper_list;
                }
                spin_unlock(&oom_reaper_lock);
 
@@ -547,13 +547,14 @@ static int oom_reaper(void *unused)
 
 static void wake_oom_reaper(struct task_struct *tsk)
 {
-       if (!oom_reaper_th)
+       if (!oom_reaper_th || tsk->oom_reaper_list)
                return;
 
        get_task_struct(tsk);
 
        spin_lock(&oom_reaper_lock);
-       list_add(&tsk->oom_reaper_list, &oom_reaper_list);
+       tsk->oom_reaper_list = oom_reaper_list;
+       oom_reaper_list = tsk;
        spin_unlock(&oom_reaper_lock);
        wake_up(&oom_reaper_wait);
 }
@@ -680,7 +681,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
        unsigned int victim_points = 0;
        static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
                                              DEFAULT_RATELIMIT_BURST);
-       bool can_oom_reap;
+       bool can_oom_reap = true;
 
        /*
         * If the task is already exiting, don't alarm the sysadmin or kill
@@ -742,10 +743,6 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
        /* Get a reference to safely compare mm after task_unlock(victim) */
        mm = victim->mm;
        atomic_inc(&mm->mm_count);
-
-       /* Make sure we do not try to oom reap the mm multiple times */
-       can_oom_reap = !test_and_set_bit(MMF_OOM_KILLED, &mm->flags);
-
        /*
         * We should send SIGKILL before setting TIF_MEMDIE in order to prevent
         * the OOM victim from depleting the memory reserves from the user