From: "Allen H. Ibara" <uce.llist@ibara.net>
To: cpufreq@lists.linux.org.uk
Cc: davej@codemonkey.org.uk
Subject: cpufreq lockdep warning
Date: Wed, 12 Jul 2006 21:02:00 -0700 [thread overview]
Message-ID: <20060713040200.GA12731@wam.verbalee.com> (raw)
Hi,
Not sure what to make of this lockdep warning with recent git i386
kernel:
=======================================================
[ INFO: possible circular locking dependency detected ]
-------------------------------------------------------
powernowd/5276 is trying to acquire lock:
(&policy->lock){--..}, at: [<c0330bed>] mutex_lock+0x1c/0x1f
but task is already holding lock:
(cpucontrol){--..}, at: [<c0330bed>] mutex_lock+0x1c/0x1f
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (cpucontrol){--..}:
[<c0135a10>] lock_acquire+0x5e/0x7e
[<c0330a67>] __mutex_lock_slowpath+0xb0/0x21a
[<c0330bed>] mutex_lock+0x1c/0x1f
[<c0138c9b>] __lock_cpu_hotplug+0x38/0x52
[<c0138d8a>] lock_cpu_hotplug+0xa/0xc
[<c02d9bcd>] __cpufreq_driver_target+0x13/0x4e
[<c02db44a>] cpufreq_governor_performance+0x1a/0x20
[<c02da145>] __cpufreq_governor+0x7c/0x14d
[<c02da420>] __cpufreq_set_policy+0xc7/0x102
[<c02da6e9>] cpufreq_set_policy+0x2d/0x6f
[<c02daa01>] cpufreq_add_dev+0x2d6/0x450
[<c027d2d5>] sysdev_driver_register+0x58/0x9b
[<c02da2dd>] cpufreq_register_driver+0x7f/0xfb
[<f898155a>] powernowk8_init+0x65/0x73 [powernow_k8]
[<c013b6f7>] sys_init_module+0x15e0/0x1741
[<c0102e5d>] sysenter_past_esp+0x56/0x8d
-> #0 (&policy->lock){--..}:
[<c0135a10>] lock_acquire+0x5e/0x7e
[<c0330a67>] __mutex_lock_slowpath+0xb0/0x21a
[<c0330bed>] mutex_lock+0x1c/0x1f
[<c02da681>] store_scaling_governor+0x120/0x15b
[<c02d9fa3>] store+0x35/0x46
[<c018e3ce>] sysfs_write_file+0xb1/0xd7
[<c015be13>] vfs_write+0x8a/0x136
[<c015c650>] sys_write+0x3b/0x60
[<c0102e5d>] sysenter_past_esp+0x56/0x8d
other info that might help us debug this:
1 lock held by powernowd/5276:
#0: (cpucontrol){--..}, at: [<c0330bed>] mutex_lock+0x1c/0x1f
I would guess that store_scaling_governor in drivers/cpufreq/cpufreq.c should
do mutex_lock(&policy->lock) before lock_cpu_hotplug() (near line 426),
but someone who's more familiar with it should probably validate that.
Thanks,
--AHI
reply other threads:[~2006-07-13 4:02 UTC|newest]
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