* deadlock in vt_kbd_con_stop
@ 2012-05-01 10:41 Clemens Ladisch
2012-05-01 12:22 ` Jiri Kosina
2012-05-01 12:31 ` Alan Cox
0 siblings, 2 replies; 3+ messages in thread
From: Clemens Ladisch @ 2012-05-01 10:41 UTC (permalink / raw)
To: Alan Cox, Greg Kroah-Hartman, linux-kernel
Pressing the Scroll Lock key in the console stops scrolling rather permanently.
(Ctrl+S/Q works fine.)
=============================================
[ INFO: possible recursive locking detected ]
3.4.0-rc5+ #354 Not tainted
---------------------------------------------
swapper/5/0 is trying to acquire lock:
(kbd_event_lock){-.....}, at: [<ffffffff8127802c>] vt_kbd_con_stop+0x1a/0x57
but task is already holding lock:
(kbd_event_lock){-.....}, at: [<ffffffff81277a84>] kbd_event+0x29/0x5b7
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(kbd_event_lock);
lock(kbd_event_lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
4 locks held by swapper/5/0:
#0: (&serio->lock){-.....}, at: [<ffffffff813abbd1>] serio_interrupt+0x24/0x7c
#1: (&(&dev->event_lock)->rlock#2){-.....}, at: [<ffffffff813b141a>] input_event+0x3a/0x7c
#2: (rcu_read_lock){.+.+..}, at: [<ffffffff813afc20>] input_pass_event+0x0/0x128
#3: (kbd_event_lock){-.....}, at: [<ffffffff81277a84>] kbd_event+0x29/0x5b7
stack backtrace:
Pid: 0, comm: swapper/5 Not tainted 3.4.0-rc5+ #354
Call Trace:
<IRQ> [<ffffffff81029562>] ? vprintk+0x3ac/0x404
[<ffffffff8106a3ed>] validate_chain+0x6ca/0xe6b
[<ffffffff8106a9d5>] ? validate_chain+0xcb2/0xe6b
[<ffffffff8106b417>] __lock_acquire+0x889/0x8fa
[<ffffffff8106b417>] ? __lock_acquire+0x889/0x8fa
[<ffffffff8106b4df>] lock_acquire+0x57/0x6d
[<ffffffff8127802c>] ? vt_kbd_con_stop+0x1a/0x57
[<ffffffff8148ddd8>] _raw_spin_lock_irqsave+0x46/0x58
[<ffffffff8127802c>] ? vt_kbd_con_stop+0x1a/0x57
[<ffffffff8127802c>] vt_kbd_con_stop+0x1a/0x57
[<ffffffff8127c0f5>] con_stop+0x26/0x28
[<ffffffff8126aad0>] stop_tty+0xa4/0xac
[<ffffffff81277823>] fn_hold+0x2a/0x2c
[<ffffffff812769d9>] k_spec+0x38/0x3a
[<ffffffff81277f7b>] kbd_event+0x520/0x5b7
[<ffffffff813afcde>] input_pass_event+0xbe/0x128
[<ffffffff813afc20>] ? input_handler_for_each_handle+0xcd/0xcd
[<ffffffff813b12e8>] input_handle_event+0x42a/0x439
[<ffffffff813b143b>] input_event+0x5b/0x7c
[<ffffffff813b7d8d>] atkbd_interrupt+0x50f/0x5de
[<ffffffff813abbed>] serio_interrupt+0x40/0x7c
[<ffffffff813ac992>] i8042_interrupt+0x289/0x2a3
[<ffffffff8107e594>] handle_irq_event_percpu+0x34/0x133
[<ffffffff8107e6cf>] handle_irq_event+0x3c/0x5c
[<ffffffff81080c4b>] handle_edge_irq+0xc7/0xec
[<ffffffff8100378e>] handle_irq+0x122/0x130
[<ffffffff810459be>] ? atomic_notifier_call_chain+0xf/0x11
[<ffffffff81002eb3>] do_IRQ+0x48/0xaf
[<ffffffff8148e6ac>] common_interrupt+0x6c/0x6c
<EOI> [<ffffffff81008ff0>] ? default_idle+0x29/0x43
[<ffffffff81008fee>] ? default_idle+0x27/0x43
[<ffffffff81009155>] amd_e400_idle+0xcd/0xf4
[<ffffffff81009289>] cpu_idle+0x73/0xb8
[<ffffffff8148674c>] start_secondary+0x225/0x227
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: deadlock in vt_kbd_con_stop
2012-05-01 10:41 deadlock in vt_kbd_con_stop Clemens Ladisch
@ 2012-05-01 12:22 ` Jiri Kosina
2012-05-01 12:31 ` Alan Cox
1 sibling, 0 replies; 3+ messages in thread
From: Jiri Kosina @ 2012-05-01 12:22 UTC (permalink / raw)
To: Clemens Ladisch; +Cc: Alan Cox, Greg Kroah-Hartman, linux-kernel
On Tue, 1 May 2012, Clemens Ladisch wrote:
> Pressing the Scroll Lock key in the console stops scrolling rather permanently.
> (Ctrl+S/Q works fine.)
>
> =============================================
> [ INFO: possible recursive locking detected ]
> 3.4.0-rc5+ #354 Not tainted
> ---------------------------------------------
> swapper/5/0 is trying to acquire lock:
> (kbd_event_lock){-.....}, at: [<ffffffff8127802c>] vt_kbd_con_stop+0x1a/0x57
>
> but task is already holding lock:
> (kbd_event_lock){-.....}, at: [<ffffffff81277a84>] kbd_event+0x29/0x5b7
>
> other info that might help us debug this:
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(kbd_event_lock);
> lock(kbd_event_lock);
>
> *** DEADLOCK ***
Seems like I have actually hit this yesterday for real, so it's not just a
theoretical scenario, see
https://lkml.org/lkml/2012/4/30/90
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: deadlock in vt_kbd_con_stop
2012-05-01 10:41 deadlock in vt_kbd_con_stop Clemens Ladisch
2012-05-01 12:22 ` Jiri Kosina
@ 2012-05-01 12:31 ` Alan Cox
1 sibling, 0 replies; 3+ messages in thread
From: Alan Cox @ 2012-05-01 12:31 UTC (permalink / raw)
To: Clemens Ladisch; +Cc: Greg Kroah-Hartman, linux-kernel
On Tue, 01 May 2012 12:41:20 +0200
Clemens Ladisch <clemens@ladisch.de> wrote:
> Pressing the Scroll Lock key in the console stops scrolling rather
> permanently. (Ctrl+S/Q works fine.)
Ok I see what is going on I think. Patch will follow very shortly.
Alan
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-05-01 10:41 deadlock in vt_kbd_con_stop Clemens Ladisch
2012-05-01 12:22 ` Jiri Kosina
2012-05-01 12:31 ` Alan Cox
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