* [PATCH -rt] printk: Don't emit console_cpu_notify() for CPU_DYING
@ 2011-11-16 9:42 Yong Zhang
2011-11-16 14:19 ` Steven Rostedt
0 siblings, 1 reply; 4+ messages in thread
From: Yong Zhang @ 2011-11-16 9:42 UTC (permalink / raw)
To: Thomas Gleixner; +Cc: LKML, linux-rt-users
Otherwise we will get below warning:
BUG: sleeping function called from invalid context at /build/linux/kernel/rtmutex.c:645
in_atomic(): 1, irqs_disabled(): 1, pid: 1054, name: migration/9
no locks held by migration/9/1054.
irq event stamp: 36
hardirqs last enabled at (35): [<ffffffff815f5b50>] _raw_spin_unlock_irq+0x30/0x70
hardirqs last disabled at (36): [<ffffffff810b7eaf>] stop_machine_cpu_stop+0x8f/0x110
softirqs last enabled at (0): [<ffffffff81051b53>] copy_process+0x6d3/0x1640
softirqs last disabled at (0): [< (null)>] (null)
Pid: 1054, comm: migration/9 Not tainted 3.2.0-rc1-rt2-11312-gbf51260-dirty #12
Call Trace:
[<ffffffff81040c4e>] __might_sleep+0x12e/0x1e0
[<ffffffff815f4d24>] rt_spin_lock+0x24/0x60
[<ffffffff810c4aa2>] ? touch_nmi_watchdog+0x42/0x80
[<ffffffff813f58f3>] serial8250_console_write+0x143/0x150
[<ffffffff81054323>] __call_console_drivers+0x93/0xb0
[<ffffffff8105438c>] _call_console_drivers+0x4c/0x80
[<ffffffff8105448d>] console_unlock+0xcd/0x240
[<ffffffff815ef5ac>] console_cpu_notify+0x26/0x2d
[<ffffffff81083744>] notifier_call_chain+0x84/0xf0
[<ffffffff810837be>] __raw_notifier_call_chain+0xe/0x10
[<ffffffff81055ac0>] __cpu_notify+0x20/0x40
[<ffffffff815de3e2>] take_cpu_down+0x32/0x40
[<ffffffff810b7eca>] stop_machine_cpu_stop+0xaa/0x110
[<ffffffff810b7e20>] ? stop_one_cpu+0x80/0x80
[<ffffffff810b7e20>] ? stop_one_cpu+0x80/0x80
[<ffffffff810b79be>] cpu_stopper_thread+0xce/0x1b0
[<ffffffff810b78f0>] ? wait_for_stop_done+0xa0/0xa0
[<ffffffff810b78f0>] ? wait_for_stop_done+0xa0/0xa0
[<ffffffff810430c9>] ? sub_preempt_count+0xa9/0xe0
[<ffffffff810b78f0>] ? wait_for_stop_done+0xa0/0xa0
[<ffffffff810b78f0>] ? wait_for_stop_done+0xa0/0xa0
[<ffffffff8107c096>] kthread+0xa6/0xb0
[<ffffffff810430c9>] ? sub_preempt_count+0xa9/0xe0
[<ffffffff815f5b5b>] ? _raw_spin_unlock_irq+0x3b/0x70
[<ffffffff815f8534>] kernel_thread_helper+0x4/0x10
[<ffffffff810423bc>] ? finish_task_switch+0x8c/0x110
[<ffffffff815f5b5b>] ? _raw_spin_unlock_irq+0x3b/0x70
[<ffffffff815f5f21>] ? retint_restore_args+0xe/0xe
[<ffffffff8107bff0>] ? kthreadd+0x160/0x160
[<ffffffff815f8530>] ? gs_change+0xb/0xb
CPU 9 is now offline
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
---
kernel/printk.c | 1 -
1 files changed, 0 insertions(+), 1 deletions(-)
diff --git a/kernel/printk.c b/kernel/printk.c
index 535bc3b..ba0393e 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1223,7 +1223,6 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self,
switch (action) {
case CPU_ONLINE:
case CPU_DEAD:
- case CPU_DYING:
case CPU_DOWN_FAILED:
case CPU_UP_CANCELED:
console_lock();
--
1.7.5.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH -rt] printk: Don't emit console_cpu_notify() for CPU_DYING
2011-11-16 9:42 [PATCH -rt] printk: Don't emit console_cpu_notify() for CPU_DYING Yong Zhang
@ 2011-11-16 14:19 ` Steven Rostedt
2011-11-16 14:48 ` Thomas Gleixner
0 siblings, 1 reply; 4+ messages in thread
From: Steven Rostedt @ 2011-11-16 14:19 UTC (permalink / raw)
To: Yong Zhang; +Cc: Thomas Gleixner, LKML, linux-rt-users
On Wed, 2011-11-16 at 17:42 +0800, Yong Zhang wrote:
> Otherwise we will get below warning:
>
> BUG: sleeping function called from invalid context at /build/linux/kernel/rtmutex.c:645
> in_atomic(): 1, irqs_disabled(): 1, pid: 1054, name: migration/9
> no locks held by migration/9/1054.
> irq event stamp: 36
> hardirqs last enabled at (35): [<ffffffff815f5b50>] _raw_spin_unlock_irq+0x30/0x70
> hardirqs last disabled at (36): [<ffffffff810b7eaf>] stop_machine_cpu_stop+0x8f/0x110
> softirqs last enabled at (0): [<ffffffff81051b53>] copy_process+0x6d3/0x1640
> softirqs last disabled at (0): [< (null)>] (null)
> Pid: 1054, comm: migration/9 Not tainted 3.2.0-rc1-rt2-11312-gbf51260-dirty #12
> Call Trace:
Thomas, doesn't printk not print to serial in atomic contexts? Or did
that change?
-- Steve
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH -rt] printk: Don't emit console_cpu_notify() for CPU_DYING
2011-11-16 14:19 ` Steven Rostedt
@ 2011-11-16 14:48 ` Thomas Gleixner
2011-11-17 5:29 ` Yong Zhang
0 siblings, 1 reply; 4+ messages in thread
From: Thomas Gleixner @ 2011-11-16 14:48 UTC (permalink / raw)
To: Steven Rostedt; +Cc: Yong Zhang, LKML, linux-rt-users
On Wed, 16 Nov 2011, Steven Rostedt wrote:
> On Wed, 2011-11-16 at 17:42 +0800, Yong Zhang wrote:
> > Otherwise we will get below warning:
> >
> > BUG: sleeping function called from invalid context at /build/linux/kernel/rtmutex.c:645
> > in_atomic(): 1, irqs_disabled(): 1, pid: 1054, name: migration/9
> > no locks held by migration/9/1054.
> > irq event stamp: 36
> > hardirqs last enabled at (35): [<ffffffff815f5b50>] _raw_spin_unlock_irq+0x30/0x70
> > hardirqs last disabled at (36): [<ffffffff810b7eaf>] stop_machine_cpu_stop+0x8f/0x110
> > softirqs last enabled at (0): [<ffffffff81051b53>] copy_process+0x6d3/0x1640
> > softirqs last disabled at (0): [< (null)>] (null)
> > Pid: 1054, comm: migration/9 Not tainted 3.2.0-rc1-rt2-11312-gbf51260-dirty #12
> > Call Trace:
>
> Thomas, doesn't printk not print to serial in atomic contexts? Or did
> that change?
Not that I know of.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH -rt] printk: Don't emit console_cpu_notify() for CPU_DYING
2011-11-16 14:48 ` Thomas Gleixner
@ 2011-11-17 5:29 ` Yong Zhang
0 siblings, 0 replies; 4+ messages in thread
From: Yong Zhang @ 2011-11-17 5:29 UTC (permalink / raw)
To: Thomas Gleixner, Steven Rostedt; +Cc: LKML, linux-rt-users
On Wed, Nov 16, 2011 at 03:48:11PM +0100, Thomas Gleixner wrote:
> On Wed, 16 Nov 2011, Steven Rostedt wrote:
> > Thomas, doesn't printk not print to serial in atomic contexts? Or did
I guess you mean console_trylock_for_printk() will fail in atomic context?
If so, yeah, that doesn't change.
But the issue is console_cpu_notify() call console_lock() directly.
That means below scenario could also happen in mainline:
CPU A CPU B
doing printk with console_sem held
take_cpu_down();
cpu_notify(CPU_DYING);
console_cpu_notify();
console_lock();
down(&console_sem);
*bang*
up(&console_sem);
Sounds I should also send this patch to mainline.
Thanks,
Yong
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2011-11-17 5:29 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2011-11-16 9:42 [PATCH -rt] printk: Don't emit console_cpu_notify() for CPU_DYING Yong Zhang
2011-11-16 14:19 ` Steven Rostedt
2011-11-16 14:48 ` Thomas Gleixner
2011-11-17 5:29 ` Yong Zhang
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