From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com,
mingo@kernel.org, peterz@infradead.org, bigeasy@linutronix.de,
tglx@linutronix.de
Subject: [tip:sched/core] sched: Init idle->on_rq in init_idle()
Date: Fri, 21 Feb 2014 13:31:28 -0800 [thread overview]
Message-ID: <tip-e037fef5fb7d2c887916576c1a288c821b6268f4@git.kernel.org> (raw)
In-Reply-To: <1391803122-4425-2-git-send-email-bigeasy@linutronix.de>
Commit-ID: e037fef5fb7d2c887916576c1a288c821b6268f4
Gitweb: http://git.kernel.org/tip/e037fef5fb7d2c887916576c1a288c821b6268f4
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Fri, 7 Feb 2014 20:58:37 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 21 Feb 2014 21:43:18 +0100
sched: Init idle->on_rq in init_idle()
We stumbled in RT over a SMP bringup issue on ARM where the
idle->on_rq == 0 was causing try_to_wakeup() on the other cpu to run
into nada land.
After adding that idle->on_rq = 1; I was able to find the root cause
of the lockup: the idle task on the newly woken up cpu was fiddling
with a sleeping spinlock, which is a nono.
I kept the init of idle->on_rq to keep the state consistent and to
avoid another long lasting debug session.
As a side note, the whole debug mess could have been avoided if
might_sleep() would have yelled when called from the idle task. That's
fixed with patch 2/6 - and that one actually has a changelog :)
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1391803122-4425-2-git-send-email-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/sched/core.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4c8aaf0..86e0558 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4451,6 +4451,7 @@ void init_idle(struct task_struct *idle, int cpu)
rcu_read_unlock();
rq->curr = rq->idle = idle;
+ idle->on_rq = 1;
#if defined(CONFIG_SMP)
idle->on_cpu = 1;
#endif
next prev parent reply other threads:[~2014-02-21 21:32 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-07 19:58 A pile of sched patches Sebastian Andrzej Siewior
2014-02-07 19:58 ` [PATCH 1/6] sched: Init idle->on_rq in init_idle() Sebastian Andrzej Siewior
2014-02-07 21:09 ` Peter Zijlstra
2014-02-11 9:17 ` [PATCH 1/6 v2] " Sebastian Andrzej Siewior
2014-02-11 9:21 ` Peter Zijlstra
2014-02-11 15:34 ` Thomas Gleixner
2014-02-11 15:51 ` Peter Zijlstra
2014-02-21 21:31 ` tip-bot for Thomas Gleixner [this message]
2014-02-22 18:01 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2014-02-07 19:58 ` [PATCH 2/6] sched: Check for idle task in might_sleep() Sebastian Andrzej Siewior
2014-02-21 21:31 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2014-02-22 18:02 ` tip-bot for Thomas Gleixner
2014-02-07 19:58 ` [PATCH 3/6] sched: Better debug output for might sleep Sebastian Andrzej Siewior
2014-02-21 21:31 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2014-02-22 18:02 ` [tip:sched/core] sched: Add better debug output for might_sleep() tip-bot for Thomas Gleixner
2014-02-07 19:58 ` [PATCH 4/6] sched: Adjust sched_reset_on_fork when nothing else changes Sebastian Andrzej Siewior
2014-02-21 21:32 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2014-02-22 18:02 ` [tip:sched/core] sched: Adjust p-> " tip-bot for Thomas Gleixner
2014-02-07 19:58 ` [PATCH 5/6] sched: Queue RT tasks to head when prio drops Sebastian Andrzej Siewior
2014-02-21 21:32 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2014-02-22 18:02 ` tip-bot for Thomas Gleixner
2014-02-07 19:58 ` [PATCH 6/6] sched: Consider pi boosting in setscheduler Sebastian Andrzej Siewior
2014-02-21 21:32 ` [tip:sched/core] " tip-bot for Thomas Gleixner
2014-02-22 18:02 ` [tip:sched/core] sched: Consider pi boosting in setscheduler() tip-bot for Thomas Gleixner
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