circular locking dependency on shutdown

[Johannes Berg]

Hi,

Every time I shut down my machine with a 2.6.29-rc2 kernel, I get a
lockdep report that scrolls off. I tried capturing it on video, the
relevant frames are here:
http://johannes.sipsolutions.net/files/shutdown-lockdep-images.tar.bz2

Some info I transscribed:

halt is trying to acquire lock
	(&per_cpu(cpu_policy_rwsem, cpu)){---}

but task is already holding lock
	(&cpu_hotplug.lock){--..}

which already yadda yadda

lock chain:
#1	(&cpu_hotplug.lock){--..}
	...
	get_online_cpus
#0	(&per_cpu(cpu_policy_rwsem, cpu))
	...
	disable_nonboot_cpus

stacktrace:
	down_write
	lock_policy_rwsem_write
	cpufreq_cpu_callback
	notifier_call_chain
	disable_nonboot_cpus
	kernel_power_off
	...


johannes

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