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From: Peter Zijlstra <peterz@infradead.org>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Dave Jones <davej@redhat.com>
Subject: Re: sched: spinlock recursion in sched_rr_get_interval
Date: Mon, 7 Jul 2014 22:05:50 +0200	[thread overview]
Message-ID: <20140707200550.GA6758@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <53BAA6DF.5060409@oracle.com>

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On Mon, Jul 07, 2014 at 09:55:43AM -0400, Sasha Levin wrote:
> I've also had this one, which looks similar:
> 
> [10375.005884] BUG: spinlock recursion on CPU#0, modprobe/10965
> [10375.006573]  lock: 0xffff8803a0fd7740, .magic: dead4ead, .owner: modprobe/10965, .owner_cpu: 15
> [10375.007412] CPU: 0 PID: 10965 Comm: modprobe Tainted: G        W      3.16.0-rc3-next-20140704-sasha-00023-g26c0906-dirty #765

Something's fucked; so we have:

debug_spin_lock_before()
	SPIN_BUG_ON(lock->owner == current, "recursion");

Causing that, _HOWEVER_ look at .owner_cpu and the reporting cpu!! How
can the lock owner, own the lock on cpu 15 and again contend with it on
CPU 0. That's impossible.

About when-ish did you start seeing things like this? Lemme go stare
hard at recent changes.

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  reply	other threads:[~2014-07-07 20:06 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-06 17:27 sched: spinlock recursion in sched_rr_get_interval Sasha Levin
2014-07-07  8:30 ` Peter Zijlstra
2014-07-07 13:55   ` Sasha Levin
2014-07-07 20:05     ` Peter Zijlstra [this message]
2014-07-07 22:47       ` Sasha Levin
2014-07-28 23:08         ` Sasha Levin
2014-09-17  9:13       ` Jovi Zhangwei
2014-12-26  6:45       ` Li Bin
2014-12-26  7:01         ` Sasha Levin
2014-12-27  9:02           ` Li Bin
2014-12-27  9:52         ` Davidlohr Bueso
2014-12-27 15:52           ` Sasha Levin
2014-12-28 20:17             ` Davidlohr Bueso
2014-12-29 14:22               ` Sasha Levin
2014-12-30  1:04               ` Sasha Levin

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