linux-kernel - Re: sched_core_balance() releasing interrupts with pi

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Message-ID: <YjIN4C8EFIOOR+o4@linutronix.de>
Date:   Wed, 16 Mar 2022 17:18:40 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: sched_core_balance() releasing interrupts with pi_lock held

On 2022-03-16 17:03:14 [+0100], To Steven Rostedt wrote:
…
> which looked right but RT still fall apart:
…
> | =====================================
> | WARNING: bad unlock balance detected!
> | 5.17.0-rc8-rt14+ #10 Not tainted
> | -------------------------------------
…
…
> It is always the local-lock that is breaks apart. Based on "locks held"
> and the lock it tries to release it looks like the lock was acquired on
> CPU-A and released on CPU-B.

with

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 33ce5cd113d8..f4675bd8f878 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5968,6 +5967,9 @@ static bool try_steal_cookie(int this, int that)
 		if (p == src->core_pick || p == src->curr)
 			goto next;
 
+		if (p->migration_disabled)
+			goto next;
+
 		if (!cpumask_test_cpu(this, &p->cpus_mask))
 			goto next;
 
on top my problems are gone. Let me do some testing and then I would
patch unless PeterZ does the yelling :)

> > Thanks,
> > 
> > -- Steve
> 
Sebastian