From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
John Kacur <jkacur@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Sasha Levin <sasha.levin@oracle.com>
Subject: Re: [PATCH 3.14-rt] sched/numa: Fix task_numa_free() lockdep splat
Date: Tue, 27 May 2014 14:52:01 -0400 [thread overview]
Message-ID: <20140527145201.6e79230f@gandalf.local.home> (raw)
In-Reply-To: <20140527182541.GH11096@twins.programming.kicks-ass.net>
On Tue, 27 May 2014 20:25:41 +0200
Peter Zijlstra <peterz@infradead.org> wrote:
> Nope, its really IRQs.
>
> do_exit()
> exit_itimers()
> itimer_delete()
> spin_lock_irqsave(&timer->it_lock, &flags);
> timer_delete_hook(timer);
> kc->timer_del(timer) := posix_cpu_timer_del()
> put_task_struct()
> __put_task_struct()
> task_numa_free()
> spin_lock(&grp->lock);
>
> Which nests the grp->lock inside the timer->it_lock, and where the
> timer->it_lock is IRQ-safe, the grp->lock is not.
>
> This allows for IRQ deadlocks.
Ah crap. I did a search on all the callers of put_task_struct(), and
somehow missed this one. Yep, I was looking for places that called
this while holding other irq safe locks.
-- Steve
next prev parent reply other threads:[~2014-05-27 18:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-09 18:12 [ANNOUNCE] 3.14.3-rt5 Sebastian Andrzej Siewior
2014-05-09 22:54 ` Pavel Vasilyev
2014-05-13 15:33 ` Sebastian Andrzej Siewior
2014-05-10 4:15 ` Mike Galbraith
2014-05-13 15:40 ` Sebastian Andrzej Siewior
2014-05-14 3:10 ` Mike Galbraith
2014-05-16 13:53 ` [patch] rt/sched: fix resursion when CONTEXT_TRACKING and PREEMPT_LAZY are enabled Mike Galbraith
2014-05-25 8:16 ` [patch v2] " Mike Galbraith
2014-05-13 13:30 ` [ANNOUNCE] 3.14.3-rt5 Juri Lelli
2015-02-16 11:29 ` Sebastian Andrzej Siewior
2015-02-16 12:34 ` Juri Lelli
2014-05-17 3:36 ` [PATCH 3.14-rt] sched/numa: Fix task_numa_free() lockdep splat Mike Galbraith
2014-05-27 18:18 ` Steven Rostedt
2014-05-27 18:25 ` Peter Zijlstra
2014-05-27 18:52 ` Steven Rostedt [this message]
2014-05-27 18:53 ` Steven Rostedt
2014-05-27 18:55 ` Steven Rostedt
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