Re: [patch 00/61] ANNOUNCE: lock validator -V1

[Michal Piotrowski]

On 29/05/06, Ingo Molnar <mingo@xxxxxxx> wrote:
> We are pleased to announce the first release of the "lock dependency
> correctness validator" kernel debugging feature, which can be downloaded
> from:
>
>   http://redhat.com/~mingo/lockdep-patches/
[snip]

I get this while loading cpufreq modules

=====================================================
[ BUG: possible circular locking deadlock detected! ]
-----------------------------------------------------
modprobe/1942 is trying to acquire lock:
(&anon_vma->lock){--..}, at: [<c10609cf>] anon_vma_link+0x1d/0xc9

but task is already holding lock:
(&mm->mmap_sem/1){--..}, at: [<c101e5a0>] copy_process+0xbc6/0x1519

which lock already depends on the new lock,
which could lead to circular deadlocks!

the existing dependency chain (in reverse order) is:

-> #1 (cpucontrol){--..}:
      [<c10394be>] lockdep_acquire+0x69/0x82
      [<c11ed759>] __mutex_lock_slowpath+0xd0/0x347
      [<c11ed9ec>] mutex_lock+0x1c/0x1f
      [<c103dda5>] __lock_cpu_hotplug+0x36/0x56
      [<c103ddde>] lock_cpu_hotplug+0xa/0xc
      [<c1199e06>] __cpufreq_driver_target+0x15/0x50
      [<c119a1c2>] cpufreq_governor_performance+0x1a/0x20
      [<c1198b0a>] __cpufreq_governor+0xa0/0x1a9
      [<c1198ce2>] __cpufreq_set_policy+0xcf/0x100
      [<c11991c6>] cpufreq_set_policy+0x2d/0x6f
      [<c1199cae>] cpufreq_add_dev+0x34f/0x492
      [<c114b8c8>] sysdev_driver_register+0x58/0x9b
      [<c119a036>] cpufreq_register_driver+0x80/0xf4
      [<fd97b02a>] ct_get_next+0x17/0x3f [ip_conntrack]
      [<c10410e1>] sys_init_module+0xa6/0x230
      [<c11ef9ab>] sysenter_past_esp+0x54/0x8d

-> #0 (&anon_vma->lock){--..}:
      [<c10394be>] lockdep_acquire+0x69/0x82
      [<c11ed759>] __mutex_lock_slowpath+0xd0/0x347
      [<c11ed9ec>] mutex_lock+0x1c/0x1f
      [<c11990eb>] cpufreq_update_policy+0x34/0xd8
      [<fd9ad50b>] cpufreq_stat_cpu_callback+0x1b/0x7c [cpufreq_stats]
      [<fd9b007d>] cpufreq_stats_init+0x7d/0x9b [cpufreq_stats]
      [<c10410e1>] sys_init_module+0xa6/0x230
      [<c11ef9ab>] sysenter_past_esp+0x54/0x8d

other info that might help us debug this:

1 locks held by modprobe/1942:
 #0:  (cpucontrol){--..}, at: [<c11ed9ec>] mutex_lock+0x1c/0x1f

stack backtrace:
<c1003f36> show_trace+0xd/0xf  <c1004449> dump_stack+0x17/0x19
<c103863e> print_circular_bug_tail+0x59/0x64  <c1038e91>
__lockdep_acquire+0x848/0xa39
<c10394be> lockdep_acquire+0x69/0x82  <c11ed759>
__mutex_lock_slowpath+0xd0/0x347
<c11ed9ec> mutex_lock+0x1c/0x1f  <c11990eb> cpufreq_update_policy+0x34/0xd8
<fd9ad50b> cpufreq_stat_cpu_callback+0x1b/0x7c [cpufreq_stats]
<fd9b007d> cpufreq_stats_init+0x7d/0x9b [cpufreq_stats]
<c10410e1> sys_init_module+0xa6/0x230  <c11ef9ab> sysenter_past_esp+0x54/0x8d

Here is dmesg http://www.stardust.webpages.pl/files/lockdep/2.6.17-rc4-mm3-lockdep1/lockdep-dmesg3

Here is config
http://www.stardust.webpages.pl/files/lockdep/2.6.17-rc4-mm3-lockdep1/lockdep-config2

BTW I still must revert lockdep-serial.patch - it doesn't compile on
my gcc 4.1.1

Regards,
Michal

--
Michal K. K. Piotrowski
LTG - Linux Testers Group
(http://www.stardust.webpages.pl/ltg/wiki/)
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