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Date: Fri, 08 Sep 2006 11:18:27 +0159
From: Jiri Slaby <jirislaby@...il.com>
To: Jiri Slaby <jirislaby@...il.com>
CC: Andrew Morton <akpm@...l.org>,
Linux Kernel <linux-kernel@...r.kernel.org>,
Arjan van de Ven <arjan@...radead.org>,
Ingo Molnar <mingo@...e.hu>, Dave Jones <davej@...hat.com>
Subject: Re: workqueue lockdep bug.
Jiri Slaby wrote:
> Andrew Morton wrote:
>> On Mon, 14 Aug 2006 14:33:19 -0400
>> Dave Jones <davej@...hat.com> wrote:
>>
>>> Andrew,
>>> I merged the workqueue changes from -mm into the Fedora-devel kernel to
>>> kill off those billion cpufreq lockdep warnings. The bug has now
>>> mutated
>>> into this:
>>>
>>> (Trimmed version of log from
>>> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=202223)
>>>
>>
>> I don't get it.
>
> Let me extend the output a little bit:
>
> clock = mutex_lock(cpu_add_remove_lock)
> wqlock = mutex_lock(workqueue_mutex)
> slock = mutex_lock(cpu_chain.rwsem)
> similar for cunlock, wqunlock, sunlock.
>
> The number after colon is linenumber, where the mutex_XXX lies.
> Prints are _after_ mutex_lock and _before_ mutex_unlock calls.
>
> So here it comes:
>
> [ 30.947289] clock: 268
> [ 30.947340] Disabling non-boot CPUs ...
> [ 30.947392] slock: 334
> [ 30.964622] wqlock: 689
> [ 30.964659] sunlock: 336
>
> Isn't this strange for validator (lock1-lock2-unlock1 +
> (below)lock1-unlock2-unlock1)?
>
> [ 30.966762] Breaking affinity for irq 0
> [ 30.968116] CPU 1 is now offline
> [ 30.968155] lockdep: not fixing up alternatives.
> [ 30.968200]
> [ 30.968201] =======================================================
> [ 30.968269] [ INFO: possible circular locking dependency detected ]
> [ 30.968307] 2.6.18-rc4-mm1-bug #11
> [ 30.968342] -------------------------------------------------------
>
>
>>> > Breaking affinity for irq 185
>>> > Breaking affinity for irq 193
>>> > Breaking affinity for irq 209
>>> > CPU 1 is now offline
>>> > lockdep: not fixing up alternatives.
>>> >
>>> > =======================================================
>>> > [ INFO: possible circular locking dependency detected ]
>>> > 2.6.17-1.2548.fc6 #1
>>> > -------------------------------------------------------
>>> > pm-hibernate/4335 is trying to acquire lock:
>>> > ((cpu_chain).rwsem){..--}, at: [<c0430fa4>]
>>> blocking_notifier_call_chain+0x11/0x2d
>>> >
>>> > but task is already holding lock:
>>> > (workqueue_mutex){--..}, at: [<c0612820>] mutex_lock+0x21/0x24
>>> >
>>> > which lock already depends on the new lock.
>>> >
>>> >
>>> > the existing dependency chain (in reverse order) is:
>>> >
>>> > -> #1 (workqueue_mutex){--..}:
>>> > [<c043c08e>] lock_acquire+0x4b/0x6d
>>> > [<c06126b1>] __mutex_lock_slowpath+0xbc/0x20a
>>> > [<c0612820>] mutex_lock+0x21/0x24
>>> > [<c0433c25>] workqueue_cpu_callback+0xfd/0x1ee
>>> > [<c0614ef5>] notifier_call_chain+0x20/0x31
>>> > [<c0430fb0>] blocking_notifier_call_chain+0x1d/0x2d
>>> > [<c043f4c5>] _cpu_down+0x47/0x1c4
>>> > [<c043f805>] disable_nonboot_cpus+0x9b/0x11a
>>> > [<c0445b32>] prepare_processes+0xe/0x41
>>> > [<c0445d87>] pm_suspend_disk+0x9/0xf3
>>> > [<c0444e12>] enter_state+0x54/0x1b7
>>> > [<c0444ffb>] state_store+0x86/0x9c
>>> > [<c04a9f88>] subsys_attr_store+0x20/0x25
>>> > [<c04aa08c>] sysfs_write_file+0xab/0xd1
>>> > [<c04732cb>] vfs_write+0xab/0x157
>>> > [<c0473910>] sys_write+0x3b/0x60
>>> > [<c0403faf>] syscall_call+0x7/0xb
>>
>> cpu_add_remove_lock -> cpu_chain.rwsem -> workqueue_mutex
>>
>>> > -> #0 ((cpu_chain).rwsem){..--}:
>>> > [<c043c08e>] lock_acquire+0x4b/0x6d
>>> > [<c04390a0>] down_read+0x2d/0x40
>>> > [<c0430fa4>] blocking_notifier_call_chain+0x11/0x2d
>>> > [<c043f5aa>] _cpu_down+0x12c/0x1c4
>>> > [<c043f805>] disable_nonboot_cpus+0x9b/0x11a
>>> > [<c0445b32>] prepare_processes+0xe/0x41
>>> > [<c0445d87>] pm_suspend_disk+0x9/0xf3
>>> > [<c0444e12>] enter_state+0x54/0x1b7
>>> > [<c0444ffb>] state_store+0x86/0x9c
>>> > [<c04a9f88>] subsys_attr_store+0x20/0x25
>>> > [<c04aa08c>] sysfs_write_file+0xab/0xd1
>>> > [<c04732cb>] vfs_write+0xab/0x157
>>> > [<c0473910>] sys_write+0x3b/0x60
>>> > [<c0403faf>] syscall_call+0x7/0xb
>>
>> cpu_add_remove_lock -> cpu_chain.rwsem
>>
>>> > other info that might help us debug this:
>>> >
>>> > 2 locks held by pm-hibernate/4335:
>>> > #0: (cpu_add_remove_lock){--..}, at: [<c0612820>]
>>> mutex_lock+0x21/0x24
>>> > #1: (workqueue_mutex){--..}, at: [<c0612820>] mutex_lock+0x21/0x24
>>> >
>>> > stack backtrace:
>>> > [<c04051ee>] show_trace_log_lvl+0x58/0x159
>>> > [<c04057ea>] show_trace+0xd/0x10
>>> > [<c0405903>] dump_stack+0x19/0x1b
>>> > [<c043b176>] print_circular_bug_tail+0x59/0x64
>>> > [<c043b98e>] __lock_acquire+0x80d/0x99c
>>> > [<c043c08e>] lock_acquire+0x4b/0x6d
>>> > [<c04390a0>] down_read+0x2d/0x40
>>> > [<c0430fa4>] blocking_notifier_call_chain+0x11/0x2d
>>> > [<c043f5aa>] _cpu_down+0x12c/0x1c4
>>> > [<c043f805>] disable_nonboot_cpus+0x9b/0x11a
>>> > [<c0445b32>] prepare_processes+0xe/0x41
>>> > [<c0445d87>] pm_suspend_disk+0x9/0xf3
>>> > [<c0444e12>] enter_state+0x54/0x1b7
>>> > [<c0444ffb>] state_store+0x86/0x9c
>>> > [<c04a9f88>] subsys_attr_store+0x20/0x25
>>> > [<c04aa08c>] sysfs_write_file+0xab/0xd1
>>> > [<c04732cb>] vfs_write+0xab/0x157
>>> > [<c0473910>] sys_write+0x3b/0x60
>>> > [<c0403faf>] syscall_call+0x7/0xb
>
> [ 30.981176] [<c0170514>] sys_write+0x47/0x6e
> [ 30.981249] [<c01031fb>] syscall_call+0x7/0xb
> [ 30.981322] =======================
> [ 30.981378] slock: 334
>
> The one, that failed.
>
> [ 30.981882] wqunlock: 702
> [ 30.981939] sunlock: 336
> [ 30.981996] CPU1 is down
> [ 30.982036] cunlock: 309
> [ 30.982075] Stopping tasks: ============
> [ 31.149008] ==================|
>
>> cpu_add_remove_lock -> cpu_chain.rwsem
>>
>> I don't see anywhere where this process took workqueue_mutex.
>
> Hope this helps?
I can't see any difference in 2.6.18-rc6-mm1. Was this somehow processed?
thanks,
--
http://www.fi.muni.cz/~xslaby/ Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8 22A0 32CC 55C3 39D4 7A7E
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