From ecda2b66e263dfd6c1d6113add19150f4e235bb3 Mon Sep 17 00:00:00 2001
From: Juri Lelli
Date: Wed, 30 May 2018 18:08:09 +0200
Subject: sched/deadline: Fix missing clock update
A missing clock update is causing the following warning:
rq->clock_update_flags < RQCF_ACT_SKIP
WARNING: CPU: 10 PID: 0 at kernel/sched/sched.h:963 inactive_task_timer+0x5d6/0x720
Call Trace:
__hrtimer_run_queues+0x10f/0x530
hrtimer_interrupt+0xe5/0x240
smp_apic_timer_interrupt+0x79/0x2b0
apic_timer_interrupt+0xf/0x20
do_idle+0x203/0x280
cpu_startup_entry+0x6f/0x80
start_secondary+0x1b0/0x200
secondary_startup_64+0xa5/0xb0
hardirqs last enabled at (793919): [] cpuidle_enter_state+0x9e/0x360
hardirqs last disabled at (793920): [] interrupt_entry+0xce/0xe0
softirqs last enabled at (793922): [] irq_enter+0x68/0x70
softirqs last disabled at (793921): [] irq_enter+0x4d/0x70
This happens because inactive_task_timer() calls sub_running_bw() (if
TASK_DEAD and non_contending) that might trigger a schedutil update,
which might access the clock. Clock is however currently updated only
later in inactive_task_timer() function.
Fix the problem by updating the clock right after task_rq_lock().
Reported-by: kernel test robot
Signed-off-by: Juri Lelli
Signed-off-by: Peter Zijlstra (Intel)
Cc: Claudio Scordino
Cc: Linus Torvalds
Cc: Luca Abeni
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/20180530160809.9074-1-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar
---
kernel/sched/deadline.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 1356afd1eeb6..fbfc3f1d368a 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1259,6 +1259,9 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
rq = task_rq_lock(p, &rf);
+ sched_clock_tick();
+ update_rq_clock(rq);
+
if (!dl_task(p) || p->state == TASK_DEAD) {
struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
@@ -1278,9 +1281,6 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer)
if (dl_se->dl_non_contending == 0)
goto unlock;
- sched_clock_tick();
- update_rq_clock(rq);
-
sub_running_bw(dl_se, &rq->dl);
dl_se->dl_non_contending = 0;
unlock:
--
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