* (WARNING) possible deadlock in del_timer_sync, called from fbcon_del_cursor_timer
@ 2011-02-28 14:41 Clemens Ladisch
2011-03-02 18:12 ` (WARNING) possible deadlock in del_timer_sync, called from Steven Rostedt
0 siblings, 1 reply; 3+ messages in thread
From: Clemens Ladisch @ 2011-02-28 14:41 UTC (permalink / raw)
To: linux-fbdev; +Cc: linux-kernel
While using the FB console, I tried to change the console log level
with SysRq, and got this warning that del_timer_sync() is used in
an interrupt handler:
SysRq :
------------[ cut here ]------------
WARNING: at kernel/timer.c:983 del_timer_sync+0x93/0xae()
Hardware name: System Product Name
Modules linked in: soundcore firewire_ohci firewire_core ohci_hcd ehci_hcd
Pid: 0, comm: kworker/0:1 Not tainted 2.6.38-rc6+ #235
Call Trace:
<IRQ> [<ffffffff8103a6df>] ? warn_slowpath_common+0x80/0x98
[<ffffffff8103a70c>] ? warn_slowpath_null+0x15/0x17
[<ffffffff810452a7>] ? del_timer_sync+0x93/0xae
[<ffffffff81045214>] ? del_timer_sync+0x0/0xae
[<ffffffff8120725a>] ? fbcon_del_cursor_timer+0x32/0x3d
[<ffffffff812077f0>] ? fbcon_cursor+0x9a/0x152
[<ffffffff8125fd84>] ? hide_cursor+0x2c/0x7d
[<ffffffff8126022b>] ? vt_console_print+0xd9/0x2f7
[<ffffffff8103a891>] ? __call_console_drivers+0x67/0x79
[<ffffffff8103a8fc>] ? _call_console_drivers+0x59/0x5d
[<ffffffff8103ae3e>] ? console_unlock+0x160/0x1ce
[<ffffffff8103b44a>] ? vprintk+0x358/0x38e
[<ffffffff81466199>] ? printk+0x3c/0x3e
[<ffffffff812594ce>] ? __handle_sysrq+0x23/0x157
[<ffffffff812594f0>] ? __handle_sysrq+0x45/0x157
[<ffffffff81259758>] ? sysrq_filter+0x116/0x17b
[<ffffffff8139b9c5>] ? input_pass_event+0xbe/0x111
[<ffffffff8139b907>] ? input_pass_event+0x0/0x111
[<ffffffff8139cfb4>] ? input_handle_event+0x42a/0x439
[<ffffffff8139d0e9>] ? input_event+0x5b/0x7a
[<ffffffff813a37f3>] ? atkbd_interrupt+0x50f/0x5e0
[<ffffffff8139735c>] ? serio_interrupt+0x40/0x7c
[<ffffffff81398647>] ? i8042_interrupt+0x289/0x2a3
[<ffffffff8107ae98>] ? handle_IRQ_event+0x20/0xa8
[<ffffffff8107cd68>] ? handle_edge_irq+0x103/0x14f
[<ffffffff81004a2b>] ? handle_irq+0x83/0x8c
[<ffffffff81004067>] ? do_IRQ+0x48/0xaf
[<ffffffff81469a93>] ? ret_from_intr+0x0/0x13
<EOI> [<ffffffff8105d49e>] ? tick_broadcast_oneshot_control+0x1a/0xfb
[<ffffffff810098cc>] ? default_idle+0x27/0x43
[<ffffffff810098ce>] ? default_idle+0x29/0x43
[<ffffffff810098cc>] ? default_idle+0x27/0x43
[<ffffffff81009a33>] ? c1e_idle+0xcd/0xf4
[<ffffffff810012e5>] ? cpu_idle+0x5f/0x96
[<ffffffff81462b7c>] ? start_secondary+0x1e3/0x1e5
---[ end trace 80565a42945fc993 ]---
Changing Loglevel
Loglevel set to 3
To add insult to injury, my cursor is configured not to blink.
Regards,
Clemens
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: (WARNING) possible deadlock in del_timer_sync, called from
2011-02-28 14:41 (WARNING) possible deadlock in del_timer_sync, called from fbcon_del_cursor_timer Clemens Ladisch
@ 2011-03-02 18:12 ` Steven Rostedt
2011-03-03 9:12 ` (WARNING) possible deadlock in del_timer_sync, called from fbcon_del_cursor_timer Yong Zhang
0 siblings, 1 reply; 3+ messages in thread
From: Steven Rostedt @ 2011-03-02 18:12 UTC (permalink / raw)
To: Clemens Ladisch; +Cc: linux-fbdev, linux-kernel, Thomas Gleixner
On Mon, Feb 28, 2011 at 03:41:07PM +0100, Clemens Ladisch wrote:
> While using the FB console, I tried to change the console log level
> with SysRq, and got this warning that del_timer_sync() is used in
> an interrupt handler:
Ug, del_timer_sync() can be called from interrupt context:
printk -> vt_console_print -> hide_cursor -> fbcon_cursor
-> fbcon_del_cursor_time -> del_timer_sync()
printk is allowed to be called from interrupt context. This is indeed a
true bug.
-- Steve
>
> SysRq :
> ------------[ cut here ]------------
> WARNING: at kernel/timer.c:983 del_timer_sync+0x93/0xae()
> Hardware name: System Product Name
> Modules linked in: soundcore firewire_ohci firewire_core ohci_hcd ehci_hcd
> Pid: 0, comm: kworker/0:1 Not tainted 2.6.38-rc6+ #235
> Call Trace:
> <IRQ> [<ffffffff8103a6df>] ? warn_slowpath_common+0x80/0x98
> [<ffffffff8103a70c>] ? warn_slowpath_null+0x15/0x17
> [<ffffffff810452a7>] ? del_timer_sync+0x93/0xae
> [<ffffffff81045214>] ? del_timer_sync+0x0/0xae
> [<ffffffff8120725a>] ? fbcon_del_cursor_timer+0x32/0x3d
> [<ffffffff812077f0>] ? fbcon_cursor+0x9a/0x152
> [<ffffffff8125fd84>] ? hide_cursor+0x2c/0x7d
> [<ffffffff8126022b>] ? vt_console_print+0xd9/0x2f7
> [<ffffffff8103a891>] ? __call_console_drivers+0x67/0x79
> [<ffffffff8103a8fc>] ? _call_console_drivers+0x59/0x5d
> [<ffffffff8103ae3e>] ? console_unlock+0x160/0x1ce
> [<ffffffff8103b44a>] ? vprintk+0x358/0x38e
> [<ffffffff81466199>] ? printk+0x3c/0x3e
> [<ffffffff812594ce>] ? __handle_sysrq+0x23/0x157
> [<ffffffff812594f0>] ? __handle_sysrq+0x45/0x157
> [<ffffffff81259758>] ? sysrq_filter+0x116/0x17b
> [<ffffffff8139b9c5>] ? input_pass_event+0xbe/0x111
> [<ffffffff8139b907>] ? input_pass_event+0x0/0x111
> [<ffffffff8139cfb4>] ? input_handle_event+0x42a/0x439
> [<ffffffff8139d0e9>] ? input_event+0x5b/0x7a
> [<ffffffff813a37f3>] ? atkbd_interrupt+0x50f/0x5e0
> [<ffffffff8139735c>] ? serio_interrupt+0x40/0x7c
> [<ffffffff81398647>] ? i8042_interrupt+0x289/0x2a3
> [<ffffffff8107ae98>] ? handle_IRQ_event+0x20/0xa8
> [<ffffffff8107cd68>] ? handle_edge_irq+0x103/0x14f
> [<ffffffff81004a2b>] ? handle_irq+0x83/0x8c
> [<ffffffff81004067>] ? do_IRQ+0x48/0xaf
> [<ffffffff81469a93>] ? ret_from_intr+0x0/0x13
> <EOI> [<ffffffff8105d49e>] ? tick_broadcast_oneshot_control+0x1a/0xfb
> [<ffffffff810098cc>] ? default_idle+0x27/0x43
> [<ffffffff810098ce>] ? default_idle+0x29/0x43
> [<ffffffff810098cc>] ? default_idle+0x27/0x43
> [<ffffffff81009a33>] ? c1e_idle+0xcd/0xf4
> [<ffffffff810012e5>] ? cpu_idle+0x5f/0x96
> [<ffffffff81462b7c>] ? start_secondary+0x1e3/0x1e5
> ---[ end trace 80565a42945fc993 ]---
> Changing Loglevel
> Loglevel set to 3
>
>
> To add insult to injury, my cursor is configured not to blink.
>
>
> Regards,
> Clemens
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: (WARNING) possible deadlock in del_timer_sync, called from fbcon_del_cursor_timer
2011-03-02 18:12 ` (WARNING) possible deadlock in del_timer_sync, called from Steven Rostedt
@ 2011-03-03 9:12 ` Yong Zhang
0 siblings, 0 replies; 3+ messages in thread
From: Yong Zhang @ 2011-03-03 9:12 UTC (permalink / raw)
To: Steven Rostedt
Cc: Clemens Ladisch, linux-fbdev, linux-kernel, Thomas Gleixner,
Andrew Morton, Jesse Barnes, Denys Vlasenko, Jason Wessel
On Thu, Mar 3, 2011 at 2:12 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Mon, Feb 28, 2011 at 03:41:07PM +0100, Clemens Ladisch wrote:
>> While using the FB console, I tried to change the console log level
>> with SysRq, and got this warning that del_timer_sync() is used in
>> an interrupt handler:
>
> Ug, del_timer_sync() can be called from interrupt context:
>
> printk -> vt_console_print -> hide_cursor -> fbcon_cursor
> -> fbcon_del_cursor_time -> del_timer_sync()
>
> printk is allowed to be called from interrupt context. This is indeed a
> true bug.
Yeah.
And more explanation for that WARN_ON() :)
run_timer_softirq(SOFTIRQ context)
cursor_timer_handler()
Interrupt comes in(IRQ context)
...
del_timer_sync()
deadlock
So fbcon guys:
Could above situation happen?
Cc'ing people from:
./scripts/get_maintainer.pl -f drivers/video/console/fbcon.c
Thanks,
Yong
--
Only stand for myself
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2011-03-03 9:12 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-02-28 14:41 (WARNING) possible deadlock in del_timer_sync, called from fbcon_del_cursor_timer Clemens Ladisch
2011-03-02 18:12 ` (WARNING) possible deadlock in del_timer_sync, called from Steven Rostedt
2011-03-03 9:12 ` (WARNING) possible deadlock in del_timer_sync, called from fbcon_del_cursor_timer Yong Zhang
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).