K99cpuspeed: possible recursive locking detected

[John Kacur]

I see the following when I shut-down 2.6.33-rc6 on my Lenovo Laptop T500

Disabling ondemand cpu frequency scaling:
=============================================
[ INFO: possible recursive locking detected ]
2.6.33-rc6 #1
---------------------------------------------
K99cpuspeed/20601 is trying to acquire lock:
 (s_active){++++.+}, at: [<ffffffff81156f5c>] sysfs_hash_and_remove+0x53/0x6a

but task is already holding lock:
 (s_active){++++.+}, at: [<ffffffff81159084>] sysfs_get_active_two+0x24/0x48

other info that might help us debug this:
4 locks held by K99cpuspeed/20601:
 #0:  (&buffer->mutex){+.+.+.}, at: [<ffffffff81157911>] sysfs_write_file+0x3e/0
x12b
 #1:  (s_active){++++.+}, at: [<ffffffff81159084>] sysfs_get_active_two+0x24/0x4
8
 #2:  (s_active){++++.+}, at: [<ffffffff81159091>] sysfs_get_active_two+0x31/0x4
8
 #3:  (dbs_mutex){+.+.+.}, at: [<ffffffffa04c4db3>] cpufreq_governor_dbs+0x29b/0
x348 [cpufreq_ondemand]

stack backtrace:
Pid: 20601, comm: K99cpuspeed Not tainted 2.6.33-rc6 #1
Call Trace:
 [<ffffffff81071f16>] __lock_acquire+0xcf6/0xd8b
 [<ffffffff810708d4>] ? debug_check_no_locks_freed+0x120/0x12f
 [<ffffffff810701ce>] ? trace_hardirqs_on_caller+0x11f/0x14a
 [<ffffffff81072083>] lock_acquire+0xd8/0xf5
 [<ffffffff81156f5c>] ? sysfs_hash_and_remove+0x53/0x6a
 [<ffffffff81158d85>] sysfs_addrm_finish+0xe1/0x175
 [<ffffffff81156f5c>] ? sysfs_hash_and_remove+0x53/0x6a
 [<ffffffff8137af35>] ? sub_preempt_count+0xa3/0xb6
 [<ffffffff81156f5c>] sysfs_hash_and_remove+0x53/0x6a
 [<ffffffff8115a0f1>] sysfs_remove_group+0x91/0xc9
 [<ffffffffa04c4dc6>] cpufreq_governor_dbs+0x2ae/0x348 [cpufreq_ondemand]
 [<ffffffff8137af35>] ? sub_preempt_count+0xa3/0xb6
 [<ffffffff812ab760>] __cpufreq_governor+0x89/0xc7
 [<ffffffff812ac54d>] __cpufreq_set_policy+0x18e/0x22a
 [<ffffffff812aca6a>] store_scaling_governor+0x199/0x1ed
 [<ffffffff812ad2a1>] ? handle_update+0x0/0x39
 [<ffffffff813765d5>] ? down_write+0x76/0x7e
 [<ffffffff81370065>] ? do_boot_cpu+0x5ff/0x653
 [<ffffffff812ac39b>] store+0x67/0x8b
 [<ffffffff811579c9>] sysfs_write_file+0xf6/0x12b
 [<ffffffff810fff45>] vfs_write+0xb0/0x10a
 [<ffffffff8110006d>] sys_write+0x4c/0x75
 [<ffffffff81002d9b>] system_call_fastpath+0x16/0x1b
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