Merge branch 'freezer'

* freezer:
  PM / freezer: Clean up code after recent fixes
  PM: convert do_each_thread to for_each_process_thread
  OOM, PM: OOM killed task shouldn't escape PM suspend
  freezer: remove obsolete comments in __thaw_task()
  freezer: Do not freeze tasks killed by OOM killer

2 files changed, 51 insertions, 15 deletions

diff --git a/kernel/freezer.c b/kernel/freezer.c
index aa6a8aadb911..a8900a3bc27a 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -42,6 +42,9 @@ bool freezing_slow_path(struct task_struct *p)
         if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK))
                 return false;
 
+        if (test_thread_flag(TIF_MEMDIE))
+                return false;
+
         if (pm_nosig_freezing || cgroup_freezing(p))
                 return true;
 
@@ -147,12 +150,6 @@ void __thaw_task(struct task_struct *p)
 {
         unsigned long flags;
 
-        /*
-         * Clear freezing and kick @p if FROZEN.  Clearing is guaranteed to
-         * be visible to @p as waking up implies wmb.  Waking up inside
-         * freezer_lock also prevents wakeups from leaking outside
-         * refrigerator.
-         */
         spin_lock_irqsave(&freezer_lock, flags);
         if (frozen(p))
                 wake_up_process(p);
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 7b323221b9ee..5a6ec8678b9a 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -46,13 +46,13 @@ static int try_to_freeze_tasks(bool user_only)
         while (true) {
                 todo = 0;
                 read_lock(&tasklist_lock);
-                do_each_thread(g, p) {
+                for_each_process_thread(g, p) {
                         if (p == current || !freeze_task(p))
                                 continue;
 
                         if (!freezer_should_skip(p))
                                 todo++;
-                } while_each_thread(g, p);
+                }
                 read_unlock(&tasklist_lock);
 
                 if (!user_only) {
@@ -93,11 +93,11 @@ static int try_to_freeze_tasks(bool user_only)
 
                 if (!wakeup) {
                         read_lock(&tasklist_lock);
-                        do_each_thread(g, p) {
+                        for_each_process_thread(g, p) {
                                 if (p != current && !freezer_should_skip(p)
                                     && freezing(p) && !frozen(p))
                                         sched_show_task(p);
-                        } while_each_thread(g, p);
+                        }
                         read_unlock(&tasklist_lock);
                 }
         } else {
@@ -108,6 +108,30 @@ static int try_to_freeze_tasks(bool user_only)
         return todo ? -EBUSY : 0;
 }
 
+static bool __check_frozen_processes(void)
+{
+        struct task_struct *g, *p;
+
+        for_each_process_thread(g, p)
+                if (p != current && !freezer_should_skip(p) && !frozen(p))
+                        return false;
+
+        return true;
+}
+
+/*
+ * Returns true if all freezable tasks (except for current) are frozen already
+ */
+static bool check_frozen_processes(void)
+{
+        bool ret;
+
+        read_lock(&tasklist_lock);
+        ret = __check_frozen_processes();
+        read_unlock(&tasklist_lock);
+        return ret;
+}
+
 /**
  * freeze_processes - Signal user space processes to enter the refrigerator.
  * The current thread will not be frozen.  The same process that calls
@@ -118,6 +142,7 @@ static int try_to_freeze_tasks(bool user_only)
 int freeze_processes(void)
 {
         int error;
+        int oom_kills_saved;
 
         error = __usermodehelper_disable(UMH_FREEZING);
         if (error)
@@ -132,11 +157,25 @@ int freeze_processes(void)
         pm_wakeup_clear();
         printk("Freezing user space processes ... ");
         pm_freezing = true;
+        oom_kills_saved = oom_kills_count();
         error = try_to_freeze_tasks(true);
         if (!error) {
-                printk("done.");
                 __usermodehelper_set_disable_depth(UMH_DISABLED);
                 oom_killer_disable();
+
+                /*
+                 * There might have been an OOM kill while we were
+                 * freezing tasks and the killed task might be still
+                 * on the way out so we have to double check for race.
+                 */
+                if (oom_kills_count() != oom_kills_saved &&
+                    !check_frozen_processes()) {
+                        __usermodehelper_set_disable_depth(UMH_ENABLED);
+                        printk("OOM in progress.");
+                        error = -EBUSY;
+                } else {
+                        printk("done.");
+                }
         }
         printk("\n");
         BUG_ON(in_atomic());
@@ -191,11 +230,11 @@ void thaw_processes(void)
         thaw_workqueues();
 
         read_lock(&tasklist_lock);
-        do_each_thread(g, p) {
+        for_each_process_thread(g, p) {
                 /* No other threads should have PF_SUSPEND_TASK set */
                 WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
                 __thaw_task(p);
-        } while_each_thread(g, p);
+        }
         read_unlock(&tasklist_lock);
 
         WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
@@ -218,10 +257,10 @@ void thaw_kernel_threads(void)
         thaw_workqueues();
 
         read_lock(&tasklist_lock);
-        do_each_thread(g, p) {
+        for_each_process_thread(g, p) {
                 if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
                         __thaw_task(p);
-        } while_each_thread(g, p);
+        }
         read_unlock(&tasklist_lock);
 
         schedule();