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

diff --git a/include/linux/oom.h b/include/linux/oom.h
index 647395a..e8d6e10 100644 (file)
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -50,6 +50,9 @@ static inline bool oom_task_origin(const struct task_struct *p)
 extern unsigned long oom_badness(struct task_struct *p,
                struct mem_cgroup *memcg, const nodemask_t *nodemask,
                unsigned long totalpages);
+
+extern int oom_kills_count(void);
+extern void note_oom_kill(void);
 extern void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
                             unsigned int points, unsigned long totalpages,
                             struct mem_cgroup *memcg, nodemask_t *nodemask,

diff --git a/kernel/freezer.c b/kernel/freezer.c
index aa6a8aa..a8900a3 100644 (file)
--- 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 7b32322..5a6ec86 100644 (file)
--- 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();

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index bbf405a..5340f6b 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -404,6 +404,23 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
                dump_tasks(memcg, nodemask);
 }
 
+/*
+ * Number of OOM killer invocations (including memcg OOM killer).
+ * Primarily used by PM freezer to check for potential races with
+ * OOM killed frozen task.
+ */
+static atomic_t oom_kills = ATOMIC_INIT(0);
+
+int oom_kills_count(void)
+{
+       return atomic_read(&oom_kills);
+}
+
+void note_oom_kill(void)
+{
+       atomic_inc(&oom_kills);
+}
+
 #define K(x) ((x) << (PAGE_SHIFT-10))
 /*
  * Must be called while holding a reference to p, which will be released upon

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 736d8e1..9cd36b8 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2251,6 +2251,14 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
                return NULL;
        }
 
+       /*
+        * PM-freezer should be notified that there might be an OOM killer on
+        * its way to kill and wake somebody up. This is too early and we might
+        * end up not killing anything but false positives are acceptable.
+        * See freeze_processes.
+        */
+       note_oom_kill();
+
        /*
         * Go through the zonelist yet one more time, keep very high watermark
         * here, this is only to catch a parallel oom killing, we must fail if