[alsa-devel] 2.6.25-rc8-mm1 -- INFO: possible circular locking dependency detected (while using iw to debug a wireless issue)

[Johannes Berg]

On Thu, 2008-04-03 at 10:41 -0400, Miles Lane wrote:
> After collecting the wireshark log, I found this in my messages log:

Below is a better version of the trace Miles sent me privately, but I
have no idea what would be causing it. I don't think it's related to
wireless.

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.25-rc8-mm1 #15
-------------------------------------------------------
iw/9417 is trying to acquire lock:
(genl_mutex){--..}, at: [ctrl_dumpfamily+0x37/0xda] ctrl_dumpfamily+0x37/0xda

but task is already holding lock:
(nlk->cb_mutex){--..}, at: [netlink_dump+0x39/0x22e] netlink_dump+0x39/0x22e

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (nlk->cb_mutex){--..}:
[__lock_acquire+0xa02/0xbaf] __lock_acquire+0xa02/0xbaf
[lock_acquire+0x76/0x9d] lock_acquire+0x76/0x9d
[snd_mixer_oss:mutex_lock_nested+0xd5/0x67b] mutex_lock_nested+0xd5/0x274
[netlink_dump_start+0xbd/0x15a] netlink_dump_start+0xbd/0x15a
[genl_rcv_msg+0x9d/0x13a] genl_rcv_msg+0x9d/0x13a
[netlink_rcv_skb+0x30/0x75] netlink_rcv_skb+0x30/0x75
[genl_rcv+0x1e/0x2e] genl_rcv+0x1e/0x2e
[cfg80211:netlink_unicast+0x1c1/0x1867] netlink_unicast+0x1c1/0x293
[netlink_sendmsg+0x21f/0x22c] netlink_sendmsg+0x21f/0x22c
[sock_sendmsg+0xca/0xe1] sock_sendmsg+0xca/0xe1
[sys_sendmsg+0x14d/0x1a8] sys_sendmsg+0x14d/0x1a8
[sys_socketcall+0x163/0x17e] sys_socketcall+0x163/0x17e
[sysenter_past_esp+0x6d/0xc5] sysenter_past_esp+0x6d/0xc5
       [<ffffffff>] 0xffffffff
-> #0 (genl_mutex){--..}:
[__lock_acquire+0x929/0xbaf] __lock_acquire+0x929/0xbaf
[lock_acquire+0x76/0x9d] lock_acquire+0x76/0x9d
[snd_mixer_oss:mutex_lock_nested+0xd5/0x67b] mutex_lock_nested+0xd5/0x274
[ctrl_dumpfamily+0x37/0xda] ctrl_dumpfamily+0x37/0xda
[netlink_dump+0x51/0x22e] netlink_dump+0x51/0x22e
[netlink_recvmsg+0x156/0x203] netlink_recvmsg+0x156/0x203
[sock_recvmsg+0xd1/0xe9] sock_recvmsg+0xd1/0xe9
[sys_recvmsg+0xf2/0x17f] sys_recvmsg+0xf2/0x17f
[sys_socketcall+0x16f/0x17e] sys_socketcall+0x16f/0x17e
[sysenter_past_esp+0x6d/0xc5] sysenter_past_esp+0x6d/0xc5
       [<ffffffff>] 0xffffffff

other info that might help us debug this:

1 lock held by iw/9417:
 #0: (nlk->cb_mutex){--..}, at: [netlink_dump+0x39/0x22e] netlink_dump+0x39/0x22e

stack backtrace:
Pid: 9417, comm: iw Not tainted 2.6.25-rc8-mm1 #15
[print_circular_bug_tail+0x5b/0x66] print_circular_bug_tail+0x5b/0x66
[print_circular_bug_header+0xa5/0xb0] ? print_circular_bug_header+0xa5/0xb0
[__lock_acquire+0x929/0xbaf] __lock_acquire+0x929/0xbaf
[lock_acquire+0x76/0x9d] lock_acquire+0x76/0x9d
[ctrl_dumpfamily+0x37/0xda] ? ctrl_dumpfamily+0x37/0xda
[snd_mixer_oss:mutex_lock_nested+0xd5/0x67b] mutex_lock_nested+0xd5/0x274
[ctrl_dumpfamily+0x37/0xda] ? ctrl_dumpfamily+0x37/0xda
[ctrl_dumpfamily+0x37/0xda] ? ctrl_dumpfamily+0x37/0xda
[ctrl_dumpfamily+0x37/0xda] ctrl_dumpfamily+0x37/0xda
[netlink_dump+0x51/0x22e] netlink_dump+0x51/0x22e
[mac80211:kfree_skb+0x40/0x45] ? kfree_skb+0x40/0x45
[netlink_recvmsg+0x156/0x203] netlink_recvmsg+0x156/0x203
[sock_sendmsg+0xca/0xe1] ? sock_sendmsg+0xca/0xe1
[sock_recvmsg+0xd1/0xe9] sock_recvmsg+0xd1/0xe9
[<c01313d9>] ? autoremove_wake_function+0x0/0x30
[snd_pcm_oss:copy_from_user+0x3b/0x236] ? copy_from_user+0x3b/0x5e
[verify_iovec+0x40/0x70] ? verify_iovec+0x40/0x70
[sys_recvmsg+0xf2/0x17f] sys_recvmsg+0xf2/0x17f
[snd_hda_intel:_spin_unlock_irqrestore+0x56/0x6c] ? _spin_unlock_irqrestore+0x56/0x6c
[paravirt_get_lazy_mode+0xe/0x1b] ? paravirt_get_lazy_mode+0xe/0x1b
[crypto_algapi:kunmap_atomic+0x9e/0x2e8e] ? kunmap_atomic+0x9e/0xbb
[handle_mm_fault+0x7aa/0x7bb] ? handle_mm_fault+0x7aa/0x7bb
[sys_socketcall+0x16f/0x17e] sys_socketcall+0x16f/0x17e
[processor:trace_hardirqs_on+0xf0/0x5d38] ? trace_hardirqs_on+0xf0/0x12c
[sysenter_past_esp+0x6d/0xc5] sysenter_past_esp+0x6d/0xc5
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