From: Oleg Nesterov <oleg@tv-sign.ru>

refrigerator() can miss a wakeup, "wait event" loop needs a proper memory
ordering.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/power/process.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff -puN kernel/power/process.c~fix-refrigerator-vs-thaw_process-race kernel/power/process.c
--- a/kernel/power/process.c~fix-refrigerator-vs-thaw_process-race
+++ a/kernel/power/process.c
@@ -47,8 +47,10 @@ void refrigerator(void)
 	recalc_sigpending(); /* We sent fake signal, clean it up */
 	spin_unlock_irq(&current->sighand->siglock);
 
-	while (frozen(current)) {
-		current->state = TASK_UNINTERRUPTIBLE;
+	for (;;) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (!frozen(current))
+			break;
 		schedule();
 	}
 	pr_debug("%s left refrigerator\n", current->comm);
_