3 files changed, 13 insertions, 1 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 50d04b92ceda..d722490da030 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1628,6 +1628,7 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
 #define PF_MEMPOLICY    0x10000000      /* Non-default NUMA mempolicy */
 #define PF_MUTEX_TESTER 0x20000000      /* Thread belongs to the rt mutex tester */
 #define PF_FREEZER_SKIP 0x40000000      /* Freezer should not count it as freezable */
+#define PF_SUSPEND_TASK 0x80000000      /* this thread called freeze_processes and should not be frozen */
 
 /*
  * Only the _current_ task can read/write to tsk->flags, but other
diff --git a/kernel/freezer.c b/kernel/freezer.c
index 8b2afc1c9df0..b462fa197517 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -33,7 +33,7 @@ static DEFINE_SPINLOCK(freezer_lock);
  */
 bool freezing_slow_path(struct task_struct *p)
 {
-        if (p->flags & PF_NOFREEZE)
+        if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK))
                 return false;
 
         if (pm_nosig_freezing || cgroup_freezing(p))
diff --git a/kernel/power/process.c b/kernel/power/process.c
index fc0df8486449..06ec8869dbf1 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -109,6 +109,8 @@ static int try_to_freeze_tasks(bool user_only)
 
 /**
  * freeze_processes - Signal user space processes to enter the refrigerator.
+ * The current thread will not be frozen.  The same process that calls
+ * freeze_processes must later call thaw_processes.
  *
  * On success, returns 0.  On failure, -errno and system is fully thawed.
  */
@@ -120,6 +122,9 @@ int freeze_processes(void)
         if (error)
                 return error;
 
+        /* Make sure this task doesn't get frozen */
+        current->flags |= PF_SUSPEND_TASK;
+
         if (!pm_freezing)
                 atomic_inc(&system_freezing_cnt);
 
@@ -168,6 +173,7 @@ int freeze_kernel_threads(void)
 void thaw_processes(void)
 {
         struct task_struct *g, *p;
+        struct task_struct *curr = current;
 
         if (pm_freezing)
                 atomic_dec(&system_freezing_cnt);
@@ -182,10 +188,15 @@ void thaw_processes(void)
 
         read_lock(&tasklist_lock);
         do_each_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));
+        curr->flags &= ~PF_SUSPEND_TASK;
+
         usermodehelper_enable();
 
         schedule();