tty Linux 3.7: possible circular locking dependency detected

From: Oliver Hartkopp
Date: Tue Dec 11 2012 - 14:56:06 EST

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Hello all,

i've seen two possible circular locking dependencies with my bluetooth dialup
setup. The dmesg outputs are attached.

Any idea?

I'll check, if i can reproduce this dmesg output.
Please let me know, if you need additional infos.

Best regards,
Oliver
[ 1003.760488] PPP generic driver version 2.4.2
[ 1008.042682] Bluetooth: TIOCGSERIAL is not supported
[ 1008.850769] Bluetooth: TIOCGSERIAL is not supported
[ 1042.449682] PPP BSD Compression module registered
[ 1042.458694] PPP Deflate Compression module registered
[ 1128.563091]
[ 1128.563097] ======================================================
[ 1128.563099] [ INFO: possible circular locking dependency detected ]
[ 1128.563103] 3.7.0 #195 Not tainted
[ 1128.563105] -------------------------------------------------------
[ 1128.563107] kworker/1:1/31 is trying to acquire lock:
[ 1128.563109] (&tty->legacy_mutex){+.+.+.}, at: [<c150f286>] tty_lock_nested+0x36/0x80
[ 1128.563123]
[ 1128.563123] but task is already holding lock:
[ 1128.563125] ((&tty->hangup_work)){+.+...}, at: [<c1052983>] process_one_work+0x123/0x4d0
[ 1128.563135]
[ 1128.563135] which lock already depends on the new lock.
[ 1128.563135]
[ 1128.563138]
[ 1128.563138] the existing dependency chain (in reverse order) is:
[ 1128.563140]
[ 1128.563140] -> #2 ((&tty->hangup_work)){+.+...}:
[ 1128.563145] [<c1085809>] lock_acquire+0x79/0xf0
[ 1128.563151] [<c1053168>] flush_work+0x48/0x250
[ 1128.563155] [<c1294a56>] tty_ldisc_flush_works+0x16/0x30
[ 1128.563160] [<c1295941>] tty_ldisc_release+0x21/0x70
[ 1128.563164] [<c128ee7c>] tty_release+0x37c/0x4a0
[ 1128.563170] [<c11175cc>] __fput+0xcc/0x1f0
[ 1128.563176] [<c11176fd>] ____fput+0xd/0x10
[ 1128.563179] [<c1056eb9>] task_work_run+0x89/0xa0
[ 1128.563184] [<c1002b11>] do_notify_resume+0x51/0x80
[ 1128.563189] [<c150f578>] work_notifysig+0x29/0x31
[ 1128.563193]
[ 1128.563193] -> #1 (&tty->legacy_mutex/1){+.+...}:
[ 1128.563199] [<c1085809>] lock_acquire+0x79/0xf0
[ 1128.563203] [<c150c1fa>] mutex_lock_nested+0x4a/0x2f0
[ 1128.563208] [<c150f286>] tty_lock_nested+0x36/0x80
[ 1128.563212] [<c150f319>] tty_lock_pair+0x29/0x70
[ 1128.563216] [<c128ec30>] tty_release+0x130/0x4a0
[ 1128.563220] [<c11175cc>] __fput+0xcc/0x1f0
[ 1128.563224] [<c11176fd>] ____fput+0xd/0x10
[ 1128.563227] [<c1056eb9>] task_work_run+0x89/0xa0
[ 1128.563231] [<c1002b11>] do_notify_resume+0x51/0x80
[ 1128.563235] [<c150f578>] work_notifysig+0x29/0x31
[ 1128.563239]
[ 1128.563239] -> #0 (&tty->legacy_mutex){+.+.+.}:
[ 1128.563243] [<c10852ae>] __lock_acquire+0x165e/0x1710
[ 1128.563248] [<c1085809>] lock_acquire+0x79/0xf0
[ 1128.563252] [<c150c1fa>] mutex_lock_nested+0x4a/0x2f0
[ 1128.563255] [<c150f286>] tty_lock_nested+0x36/0x80
[ 1128.563259] [<c150f2df>] tty_lock+0xf/0x20
[ 1128.563263] [<c128d904>] __tty_hangup+0x54/0x430
[ 1128.563267] [<c128dcf2>] do_tty_hangup+0x12/0x20
[ 1128.563272] [<c1052a02>] process_one_work+0x1a2/0x4d0
[ 1128.563275] [<c1054509>] worker_thread+0x119/0x3b0
[ 1128.563279] [<c105a1ff>] kthread+0x9f/0xb0
[ 1128.563283] [<c150fc37>] ret_from_kernel_thread+0x1b/0x28
[ 1128.563287]
[ 1128.563287] other info that might help us debug this:
[ 1128.563287]
[ 1128.563290] Chain exists of:
[ 1128.563290] &tty->legacy_mutex --> &tty->legacy_mutex/1 --> (&tty->hangup_work)
[ 1128.563290]
[ 1128.563297] Possible unsafe locking scenario:
[ 1128.563297]
[ 1128.563299] CPU0 CPU1
[ 1128.563301] ---- ----
[ 1128.563302] lock((&tty->hangup_work));
[ 1128.563305] lock(&tty->legacy_mutex/1);
[ 1128.563309] lock((&tty->hangup_work));
[ 1128.563312] lock(&tty->legacy_mutex);
[ 1128.563315]
[ 1128.563315] *** DEADLOCK ***
[ 1128.563315]
[ 1128.563319] 2 locks held by kworker/1:1/31:
[ 1128.563320] #0: (events){.+.+.+}, at: [<c1052983>] process_one_work+0x123/0x4d0
[ 1128.563328] #1: ((&tty->hangup_work)){+.+...}, at: [<c1052983>] process_one_work+0x123/0x4d0
[ 1128.563335]
[ 1128.563335] stack backtrace:
[ 1128.563339] Pid: 31, comm: kworker/1:1 Not tainted 3.7.0 #195
[ 1128.563341] Call Trace:
[ 1128.563348] [<c1506992>] print_circular_bug+0x1af/0x1b9
[ 1128.563352] [<c10852ae>] __lock_acquire+0x165e/0x1710
[ 1128.563358] [<c1085809>] lock_acquire+0x79/0xf0
[ 1128.563362] [<c150f286>] ? tty_lock_nested+0x36/0x80
[ 1128.563366] [<c150c1fa>] mutex_lock_nested+0x4a/0x2f0
[ 1128.563370] [<c150f286>] ? tty_lock_nested+0x36/0x80
[ 1128.563375] [<c128d8d2>] ? __tty_hangup+0x22/0x430
[ 1128.563379] [<c150f286>] tty_lock_nested+0x36/0x80
[ 1128.563383] [<c150f2df>] tty_lock+0xf/0x20
[ 1128.563388] [<c128d904>] __tty_hangup+0x54/0x430
[ 1128.563391] [<c1052983>] ? process_one_work+0x123/0x4d0
[ 1128.563396] [<c128dcf2>] do_tty_hangup+0x12/0x20
[ 1128.563400] [<c1052a02>] process_one_work+0x1a2/0x4d0
[ 1128.563403] [<c1052983>] ? process_one_work+0x123/0x4d0
[ 1128.563407] [<c10545ae>] ? worker_thread+0x1be/0x3b0
[ 1128.563411] [<c128dce0>] ? __tty_hangup+0x430/0x430
[ 1128.563415] [<c1054509>] worker_thread+0x119/0x3b0
[ 1128.563419] [<c10543f0>] ? __next_gcwq_cpu+0x60/0x60
[ 1128.563424] [<c105a1ff>] kthread+0x9f/0xb0
[ 1128.563428] [<c150fc37>] ret_from_kernel_thread+0x1b/0x28
[ 1128.563433] [<c105a160>] ? kthread_create_on_node+0xe0/0xe0
[ 14.711344] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 14.713505] Bluetooth: BNEP socket layer initialized
[ 14.714497] Bluetooth: RFCOMM TTY layer initialized
[ 14.714511] Bluetooth: RFCOMM socket layer initialized
[ 14.714512] Bluetooth: RFCOMM ver 1.11
[ 15.385668] input: ACPI Virtual Keyboard Device as /devices/virtual/input/input17
[ 57.826528] PPP generic driver version 2.4.2
[ 66.309295]
[ 66.309301] ======================================================
[ 66.309303] [ INFO: possible circular locking dependency detected ]
[ 66.309307] 3.7.0 #195 Not tainted
[ 66.309308] -------------------------------------------------------
[ 66.309310] kworker/2:1/35 is trying to acquire lock:
[ 66.309313] (&tty->legacy_mutex){+.+.+.}, at: [<c150f286>] tty_lock_nested+0x36/0x80
[ 66.309328]
[ 66.309328] but task is already holding lock:
[ 66.309330] ((&tty->hangup_work)){+.+...}, at: [<c1052983>] process_one_work+0x123/0x4d0
[ 66.309340]
[ 66.309340] which lock already depends on the new lock.
[ 66.309340]
[ 66.309343]
[ 66.309343] the existing dependency chain (in reverse order) is:
[ 66.309345]
[ 66.309345] -> #2 ((&tty->hangup_work)){+.+...}:
[ 66.309351] [<c1085809>] lock_acquire+0x79/0xf0
[ 66.309357] [<c1053168>] flush_work+0x48/0x250
[ 66.309360] [<c1294a56>] tty_ldisc_flush_works+0x16/0x30
[ 66.309366] [<c1295941>] tty_ldisc_release+0x21/0x70
[ 66.309370] [<c128ee7c>] tty_release+0x37c/0x4a0
[ 66.309376] [<c11175cc>] __fput+0xcc/0x1f0
[ 66.309381] [<c11176fd>] ____fput+0xd/0x10
[ 66.309385] [<c1056eb9>] task_work_run+0x89/0xa0
[ 66.309390] [<c1002b11>] do_notify_resume+0x51/0x80
[ 66.309394] [<c150f578>] work_notifysig+0x29/0x31
[ 66.309399]
[ 66.309399] -> #1 (&tty->legacy_mutex/1){+.+...}:
[ 66.309405] [<c1085809>] lock_acquire+0x79/0xf0
[ 66.309409] [<c150c1fa>] mutex_lock_nested+0x4a/0x2f0
[ 66.309413] [<c150f286>] tty_lock_nested+0x36/0x80
[ 66.309417] [<c150f319>] tty_lock_pair+0x29/0x70
[ 66.309421] [<c128ec30>] tty_release+0x130/0x4a0
[ 66.309425] [<c11175cc>] __fput+0xcc/0x1f0
[ 66.309429] [<c11176fd>] ____fput+0xd/0x10
[ 66.309432] [<c1056eb9>] task_work_run+0x89/0xa0
[ 66.309436] [<c1002b11>] do_notify_resume+0x51/0x80
[ 66.309440] [<c150f578>] work_notifysig+0x29/0x31
[ 66.309444]
[ 66.309444] -> #0 (&tty->legacy_mutex){+.+.+.}:
[ 66.309448] [<c10852ae>] __lock_acquire+0x165e/0x1710
[ 66.309453] [<c1085809>] lock_acquire+0x79/0xf0
[ 66.309456] [<c150c1fa>] mutex_lock_nested+0x4a/0x2f0
[ 66.309460] [<c150f286>] tty_lock_nested+0x36/0x80
[ 66.309464] [<c150f2df>] tty_lock+0xf/0x20
[ 66.309468] [<c128d904>] __tty_hangup+0x54/0x430
[ 66.309472] [<c128dcf2>] do_tty_hangup+0x12/0x20
[ 66.309476] [<c1052a02>] process_one_work+0x1a2/0x4d0
[ 66.309480] [<c1054509>] worker_thread+0x119/0x3b0
[ 66.309484] [<c105a1ff>] kthread+0x9f/0xb0
[ 66.309488] [<c150fc37>] ret_from_kernel_thread+0x1b/0x28
[ 66.309492]
[ 66.309492] other info that might help us debug this:
[ 66.309492]
[ 66.309495] Chain exists of:
[ 66.309495] &tty->legacy_mutex --> &tty->legacy_mutex/1 --> (&tty->hangup_work)
[ 66.309495]
[ 66.309502] Possible unsafe locking scenario:
[ 66.309502]
[ 66.309504] CPU0 CPU1
[ 66.309506] ---- ----
[ 66.309507] lock((&tty->hangup_work));
[ 66.309510] lock(&tty->legacy_mutex/1);
[ 66.309514] lock((&tty->hangup_work));
[ 66.309517] lock(&tty->legacy_mutex);
[ 66.309520]
[ 66.309520] *** DEADLOCK ***
[ 66.309520]
[ 66.309524] 2 locks held by kworker/2:1/35:
[ 66.309525] #0: (events){.+.+.+}, at: [<c1052983>] process_one_work+0x123/0x4d0
[ 66.309532] #1: ((&tty->hangup_work)){+.+...}, at: [<c1052983>] process_one_work+0x123/0x4d0
[ 66.309539]
[ 66.309539] stack backtrace:
[ 66.309543] Pid: 35, comm: kworker/2:1 Not tainted 3.7.0 #195
[ 66.309545] Call Trace:
[ 66.309552] [<c1506992>] print_circular_bug+0x1af/0x1b9
[ 66.309556] [<c10852ae>] __lock_acquire+0x165e/0x1710
[ 66.309562] [<c1085809>] lock_acquire+0x79/0xf0
[ 66.309566] [<c150f286>] ? tty_lock_nested+0x36/0x80
[ 66.309571] [<c150c1fa>] mutex_lock_nested+0x4a/0x2f0
[ 66.309575] [<c150f286>] ? tty_lock_nested+0x36/0x80
[ 66.309579] [<c128d8d2>] ? __tty_hangup+0x22/0x430
[ 66.309583] [<c150f286>] tty_lock_nested+0x36/0x80
[ 66.309588] [<c150f2df>] tty_lock+0xf/0x20
[ 66.309592] [<c128d904>] __tty_hangup+0x54/0x430
[ 66.309596] [<c1052983>] ? process_one_work+0x123/0x4d0
[ 66.309600] [<c128dcf2>] do_tty_hangup+0x12/0x20
[ 66.309604] [<c1052a02>] process_one_work+0x1a2/0x4d0
[ 66.309607] [<c1052983>] ? process_one_work+0x123/0x4d0
[ 66.309611] [<c10545ae>] ? worker_thread+0x1be/0x3b0
[ 66.309616] [<c128dce0>] ? __tty_hangup+0x430/0x430
[ 66.309620] [<c1054509>] worker_thread+0x119/0x3b0
[ 66.309624] [<c10543f0>] ? __next_gcwq_cpu+0x60/0x60
[ 66.309628] [<c105a1ff>] kthread+0x9f/0xb0
[ 66.309633] [<c150fc37>] ret_from_kernel_thread+0x1b/0x28
[ 66.309637] [<c105a160>] ? kthread_create_on_node+0xe0/0xe0

Next message: Neil Horman: "[PATCH] core_pattern: set core helpers root and namespace to crashing process"
Previous message: Nathan Zimmer: "[PATCH 4/4] Convert timer list to be a proper seq_file."
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