From: Thomas Gleixner <tglx@linutronix.de>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com,
peterz@infradead.org, fweisbec@gmail.com
Subject: Re: RCU used on incoming CPU before rcu_cpu_starting() called
Date: Thu, 9 Mar 2017 14:08:23 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1703091406490.3521@nanos> (raw)
In-Reply-To: <20170308221656.GA11949@linux.vnet.ibm.com>
On Wed, 8 Mar 2017, Paul E. McKenney wrote:
> [ 30.694013] lockdep_rcu_suspicious+0xe7/0x120
> [ 30.694013] get_work_pool+0x82/0x90
> [ 30.694013] __queue_work+0x70/0x5f0
> [ 30.694013] queue_work_on+0x33/0x70
> [ 30.694013] clear_sched_clock_stable+0x33/0x40
> [ 30.694013] early_init_intel+0xe7/0x2f0
> [ 30.694013] init_intel+0x11/0x350
> [ 30.694013] identify_cpu+0x344/0x5a0
> [ 30.694013] identify_secondary_cpu+0x18/0x80
> [ 30.694013] smp_store_cpu_info+0x39/0x40
> [ 30.694013] start_secondary+0x4e/0x100
> [ 30.694013] start_cpu+0x14/0x14
>
> Here is the relevant code from x86's smp_callin():
>
> /*
> * Save our processor parameters. Note: this information
> * is needed for clock calibration.
> */
> smp_store_cpu_info(cpuid);
>
> The problem is that smp_store_cpu_info() indirectly invokes
> schedule_work(), which wants to use RCU. But RCU isn't informed
> of the incoming CPU until the call to notify_cpu_starting(), which
> causes lockdep to complain bitterly about the use of RCU by the
> premature call to schedule_work().
Right. And that want's to be fixed, not hacked around by silencing RCU.
Peter????
Thanks,
tglx
next prev parent reply other threads:[~2017-03-09 13:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-08 22:16 RCU used on incoming CPU before rcu_cpu_starting() called Paul E. McKenney
2017-03-08 23:41 ` Paul E. McKenney
2017-03-09 3:55 ` Frederic Weisbecker
2017-03-09 5:24 ` Paul E. McKenney
2017-03-09 13:08 ` Thomas Gleixner [this message]
2017-03-09 15:12 ` Peter Zijlstra
2017-03-09 15:29 ` Paul E. McKenney
2017-03-09 15:50 ` Paul E. McKenney
2017-03-20 8:32 ` Tomeu Vizoso
2017-03-20 12:50 ` Paul E. McKenney
2017-03-09 15:24 ` Paul E. McKenney
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