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Date: Mon, 11 May 2009 00:22:26 +0900
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: LKML <linux-kernel@...r.kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
Greg KH <greg@...ah.com>, Ingo Molnar <mingo@...e.hu>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Ben Slusky <sluskyb@...anoiacs.org>,
Dave Jones <davej@...hat.com>,
Chris Wright <chrisw@...s-sol.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: lockdep warnings: cpufreq ondemand gorvernor possibly circular
locking
Hi
my box output following warnings.
it seems regression by commit 7ccc7608b836e58fbacf65ee4f8eefa288e86fac.
A: work -> do_dbs_timer() -> cpu_policy_rwsem
B: store() -> cpu_policy_rwsem -> cpufreq_governor_dbs() -> work
=======================================================
nd cpu frequency[ INFO: possible circular locking dependency detected ]
scaling: 2.6.30-rc4-mm1 #26
-------------------------------------------------------
K99cpuspeed/227488 is trying to acquire lock:
(&(&dbs_info->work)->work){+.+...}, at: [<ffffffff81055bfd>]
__cancel_work_timer+0xde/0x227
but task is already holding lock:
(dbs_mutex){+.+.+.}, at: [<ffffffffa0081af3>]
cpufreq_governor_dbs+0x241/0x2d2 [cpufreq_ondemand]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (dbs_mutex){+.+.+.}:
[<ffffffff8106a15a>] __lock_acquire+0xa9d/0xc33
[<ffffffff8106a3b1>] lock_acquire+0xc1/0xe5
[<ffffffff81303aa5>] __mutex_lock_common+0x4d/0x34c
[<ffffffff81303e5c>] mutex_lock_nested+0x3a/0x3f
[<ffffffffa008193d>] cpufreq_governor_dbs+0x8b/0x2d2 [cpufreq_ondemand]
[<ffffffff812678bd>] __cpufreq_governor+0xa7/0xe4
[<ffffffff81267acf>] __cpufreq_set_policy+0x19a/0x216
[<ffffffff81268572>] store_scaling_governor+0x1ec/0x228
[<ffffffff812691fb>] store+0x67/0x8c
[<ffffffff81129091>] sysfs_write_file+0xe9/0x11e
[<ffffffff810e64d8>] vfs_write+0xb0/0x10a
[<ffffffff810e6600>] sys_write+0x4c/0x74
[<ffffffff8100bc1b>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff
-> #1 (&per_cpu(cpu_policy_rwsem, cpu)){+++++.}:
[<ffffffff8106a15a>] __lock_acquire+0xa9d/0xc33
[<ffffffff8106a3b1>] lock_acquire+0xc1/0xe5
[<ffffffff813040d8>] down_write+0x4d/0x81
[<ffffffff81268ad3>] lock_policy_rwsem_write+0x4d/0x7d
[<ffffffffa0081692>] do_dbs_timer+0x64/0x284 [cpufreq_ondemand]
[<ffffffff81055395>] worker_thread+0x205/0x318
[<ffffffff8105933f>] kthread+0x8d/0x95
[<ffffffff8100ccfa>] child_rip+0xa/0x20
[<ffffffffffffffff>] 0xffffffffffffffff
-> #0 (&(&dbs_info->work)->work){+.+...}:
[<ffffffff8106a04e>] __lock_acquire+0x991/0xc33
[<ffffffff8106a3b1>] lock_acquire+0xc1/0xe5
[<ffffffff81055c36>] __cancel_work_timer+0x117/0x227
[<ffffffff81055d58>] cancel_delayed_work_sync+0x12/0x14
[<ffffffffa0081b06>] cpufreq_governor_dbs+0x254/0x2d2
[cpufreq_ondemand]
[<ffffffff812678bd>] __cpufreq_governor+0xa7/0xe4
[<ffffffff81267ab9>] __cpufreq_set_policy+0x184/0x216
[<ffffffff81268572>] store_scaling_governor+0x1ec/0x228
[<ffffffff812691fb>] store+0x67/0x8c
[<ffffffff81129091>] sysfs_write_file+0xe9/0x11e
[<ffffffff810e64d8>] vfs_write+0xb0/0x10a
[<ffffffff810e6600>] sys_write+0x4c/0x74
[<ffffffff8100bc1b>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff
other info that might help us debug this:
3 locks held by K99cpuspeed/227488:
#0: (&buffer->mutex){+.+.+.}, at: [<ffffffff81128fe5>]
sysfs_write_file+0x3d/0x11e
#1: (&per_cpu(cpu_policy_rwsem, cpu)){+++++.}, at:
[<ffffffff81268ad3>] lock_policy_rwsem_write+0x4d/0x7d
#2: (dbs_mutex){+.+.+.}, at: [<ffffffffa0081af3>]
cpufreq_governor_dbs+0x241/0x2d2 [cpufreq_ondemand]
stack backtrace:
Pid: 227488, comm: K99cpuspeed Not tainted 2.6.30-rc4-mm1 #26
Call Trace:
[<ffffffff81069347>] print_circular_bug_tail+0x71/0x7c
[<ffffffff8106a04e>] __lock_acquire+0x991/0xc33
[<ffffffff8104e2f6>] ? lock_timer_base+0x2b/0x4f
[<ffffffff8106a3b1>] lock_acquire+0xc1/0xe5
[<ffffffff81055bfd>] ? __cancel_work_timer+0xde/0x227
[<ffffffff81055c36>] __cancel_work_timer+0x117/0x227
[<ffffffff81055bfd>] ? __cancel_work_timer+0xde/0x227
[<ffffffff81068a22>] ? mark_held_locks+0x4d/0x6b
[<ffffffff81303d5a>] ? __mutex_lock_common+0x302/0x34c
[<ffffffffa0081af3>] ? cpufreq_governor_dbs+0x241/0x2d2 [cpufreq_ondemand]
[<ffffffff81068a22>] ? mark_held_locks+0x4d/0x6b
[<ffffffffa0081af3>] ? cpufreq_governor_dbs+0x241/0x2d2 [cpufreq_ondemand]
[<ffffffff8100b956>] ? ftrace_call+0x5/0x2b
[<ffffffff81055d58>] cancel_delayed_work_sync+0x12/0x14
[<ffffffffa0081b06>] cpufreq_governor_dbs+0x254/0x2d2 [cpufreq_ondemand]
[<ffffffff8105ce4d>] ? up_read+0x2b/0x2f
[<ffffffff812678bd>] __cpufreq_governor+0xa7/0xe4
[<ffffffff81267ab9>] __cpufreq_set_policy+0x184/0x216
[<ffffffff81268572>] store_scaling_governor+0x1ec/0x228
[<ffffffff81269354>] ? handle_update+0x0/0x39
[<ffffffff812691fb>] store+0x67/0x8c
[<ffffffff81129091>] sysfs_write_file+0xe9/0x11e
[<ffffffff810e64d8>] vfs_write+0xb0/0x10a
[<ffffffff810e6600>] sys_write+0x4c/0x74
[<ffffffff8100bc1b>] system_call_fastpath+0x16/0x1b
[ OK ]
Sending all processes th
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