sched: fix /proc/<PID>/stat stime/utime monotonicity, part 2

Extend Peter's patch to fix accounting issues, by keeping stime
monotonic too.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Frans Pop <elendil@planet.nl>
diff --git a/fs/proc/array.c b/fs/proc/array.c
index d80baaa..eba339ec 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -374,7 +374,8 @@
 	stime = nsec_to_clock_t(p->se.sum_exec_runtime) -
 			cputime_to_clock_t(task_utime(p));
 
-	return clock_t_to_cputime(stime);
+	p->prev_stime = max(p->prev_stime, clock_t_to_cputime(stime));
+	return p->prev_stime;
 }
 #endif