1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 5e75e26d4787..db5423eae24d 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -37,14 +37,24 @@ static inline void do_not_freeze(struct task_struct *p)
 
 /*
  * Wake up a frozen process
+ *
+ * task_lock() is taken to prevent the race with refrigerator() which may
+ * occur if the freezing of tasks fails.  Namely, without the lock, if the
+ * freezing of tasks failed, thaw_tasks() might have run before a task in
+ * refrigerator() could call frozen_process(), in which case the task would be
+ * frozen and no one would thaw it.
  */
 static inline int thaw_process(struct task_struct *p)
 {
+        task_lock(p);
         if (frozen(p)) {
                 p->flags &= ~PF_FROZEN;
+                task_unlock(p);
                 wake_up_process(p);
                 return 1;
         }
+        clear_tsk_thread_flag(p, TIF_FREEZE);
+        task_unlock(p);
         return 0;
 }