* [patch V2 03/29] lockup_detector: Provide interface to stop from poweroff()
[not found] <20170912193654.321505854@linutronix.de>
@ 2017-09-12 19:36 ` Thomas Gleixner
2017-09-12 19:36 ` [patch V2 04/29] parisc: Use lockup_detector_stop() Thomas Gleixner
1 sibling, 0 replies; 4+ messages in thread
From: Thomas Gleixner @ 2017-09-12 19:36 UTC (permalink / raw)
To: LKML
Cc: Ingo Molnar, Peter Zijlstra, Borislav Petkov, Andrew Morton,
Sebastian Siewior, Nicholas Piggin, Don Zickus, Chris Metcalf,
Ulrich Obergfell, linux-parisc, Helge Deller
PARISC has a a busy looping power off routine. If the watchdog is enabled
the watchdog timer will still fire, but the thread is not running, which
causes the softlockup watchdog to trigger.
Provide a interface which allows to turn the watchdog off.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: linux-parisc@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Helge Deller <deller@gmx.de>
Link: http://lkml.kernel.org/r/20170831073053.202164272@linutronix.de
---
include/linux/nmi.h | 6 +++---
kernel/watchdog.c | 14 +++++++++++++-
2 files changed, 16 insertions(+), 4 deletions(-)
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -12,10 +12,10 @@
#ifdef CONFIG_LOCKUP_DETECTOR
void lockup_detector_init(void);
+void lockup_detector_soft_poweroff(void);
#else
-static inline void lockup_detector_init(void)
-{
-}
+static inline void lockup_detector_init(void) { }
+static inline void lockup_detector_soft_poweroff(void) { }
#endif
#ifdef CONFIG_SOFTLOCKUP_DETECTOR
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -333,7 +333,8 @@ static enum hrtimer_restart watchdog_tim
int duration;
int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
- if (atomic_read(&watchdog_park_in_progress) != 0)
+ if (!watchdog_enabled ||
+ atomic_read(&watchdog_park_in_progress) != 0)
return HRTIMER_NORESTART;
/* kick the hardlockup detector */
@@ -660,6 +661,17 @@ static void set_sample_period(void)
}
#endif /* SOFTLOCKUP */
+/**
+ * lockup_detector_soft_poweroff - Interface to stop lockup detector(s)
+ *
+ * Special interface for parisc. It prevents lockup detector warnings from
+ * the default pm_poweroff() function which busy loops forever.
+ */
+void lockup_detector_soft_poweroff(void)
+{
+ watchdog_enabled = 0;
+}
+
/*
* Suspend the hard and soft lockup detector by parking the watchdog threads.
*/
^ permalink raw reply [flat|nested] 4+ messages in thread
* [patch V2 04/29] parisc: Use lockup_detector_stop()
[not found] <20170912193654.321505854@linutronix.de>
2017-09-12 19:36 ` [patch V2 03/29] lockup_detector: Provide interface to stop from poweroff() Thomas Gleixner
@ 2017-09-12 19:36 ` Thomas Gleixner
2017-09-14 8:59 ` Helge Deller
1 sibling, 1 reply; 4+ messages in thread
From: Thomas Gleixner @ 2017-09-12 19:36 UTC (permalink / raw)
To: LKML
Cc: Ingo Molnar, Peter Zijlstra, Borislav Petkov, Andrew Morton,
Sebastian Siewior, Nicholas Piggin, Don Zickus, Chris Metcalf,
Ulrich Obergfell, linux-parisc, Helge Deller
The broken lockup_detector_suspend/resume() interface is going away. Use
the new lockup_detector_soft_poweroff() interface to stop the watchdog from
the busy looping power off routine.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: linux-parisc@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Helge Deller <deller@gmx.de>
Link: http://lkml.kernel.org/r/20170831073053.281414373@linutronix.de
---
arch/parisc/kernel/process.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -146,7 +146,7 @@ void machine_power_off(void)
/* prevent soft lockup/stalled CPU messages for endless loop. */
rcu_sysrq_start();
- lockup_detector_suspend();
+ lockup_detector_soft_poweroff();
for (;;);
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [patch V2 04/29] parisc: Use lockup_detector_stop()
2017-09-12 19:36 ` [patch V2 04/29] parisc: Use lockup_detector_stop() Thomas Gleixner
@ 2017-09-14 8:59 ` Helge Deller
2017-09-14 13:46 ` Don Zickus
0 siblings, 1 reply; 4+ messages in thread
From: Helge Deller @ 2017-09-14 8:59 UTC (permalink / raw)
To: Thomas Gleixner
Cc: LKML, Ingo Molnar, Peter Zijlstra, Borislav Petkov,
Andrew Morton, Sebastian Siewior, Nicholas Piggin, Don Zickus,
Chris Metcalf, Ulrich Obergfell, linux-parisc, Helge Deller
* Thomas Gleixner <tglx@linutronix.de>:
> The broken lockup_detector_suspend/resume() interface is going away. Use
> the new lockup_detector_soft_poweroff() interface to stop the watchdog from
> the busy looping power off routine.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Don Zickus <dzickus@redhat.com>
> Cc: Chris Metcalf <cmetcalf@mellanox.com>
> Cc: linux-parisc@vger.kernel.org
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Sebastian Siewior <bigeasy@linutronix.de>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Ulrich Obergfell <uobergfe@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Helge Deller <deller@gmx.de>
> Link: http://lkml.kernel.org/r/20170831073053.281414373@linutronix.de
>
> ---
> arch/parisc/kernel/process.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/parisc/kernel/process.c
> +++ b/arch/parisc/kernel/process.c
> @@ -146,7 +146,7 @@ void machine_power_off(void)
>
> /* prevent soft lockup/stalled CPU messages for endless loop. */
> rcu_sysrq_start();
> - lockup_detector_suspend();
> + lockup_detector_soft_poweroff();
> for (;;);
> }
Thomas, thanks for cleaning that up.
You may add to patches 03/04:
Acked-by: Helge Deller <deller@gmx.de>
On a side-note, there is sadly no general function like
turn_off_all_kind_of_runtime_hang_detectors()
which turns off *all* detectors at once (including soft lockup detector).
I've seen another detector complaing at runtime that we were hanging
here. I would need to dig up more info if you are interested...
Helge
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [patch V2 04/29] parisc: Use lockup_detector_stop()
2017-09-14 8:59 ` Helge Deller
@ 2017-09-14 13:46 ` Don Zickus
0 siblings, 0 replies; 4+ messages in thread
From: Don Zickus @ 2017-09-14 13:46 UTC (permalink / raw)
To: Helge Deller
Cc: Thomas Gleixner, LKML, Ingo Molnar, Peter Zijlstra,
Borislav Petkov, Andrew Morton, Sebastian Siewior,
Nicholas Piggin, Chris Metcalf, Ulrich Obergfell, linux-parisc
On Thu, Sep 14, 2017 at 10:59:17AM +0200, Helge Deller wrote:
> * Thomas Gleixner <tglx@linutronix.de>:
> > The broken lockup_detector_suspend/resume() interface is going away. Use
> > the new lockup_detector_soft_poweroff() interface to stop the watchdog from
> > the busy looping power off routine.
> >
> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Don Zickus <dzickus@redhat.com>
> > Cc: Chris Metcalf <cmetcalf@mellanox.com>
> > Cc: linux-parisc@vger.kernel.org
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Sebastian Siewior <bigeasy@linutronix.de>
> > Cc: Nicholas Piggin <npiggin@gmail.com>
> > Cc: Ulrich Obergfell <uobergfe@redhat.com>
> > Cc: Borislav Petkov <bp@alien8.de>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Helge Deller <deller@gmx.de>
> > Link: http://lkml.kernel.org/r/20170831073053.281414373@linutronix.de
> >
> > ---
> > arch/parisc/kernel/process.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > --- a/arch/parisc/kernel/process.c
> > +++ b/arch/parisc/kernel/process.c
> > @@ -146,7 +146,7 @@ void machine_power_off(void)
> >
> > /* prevent soft lockup/stalled CPU messages for endless loop. */
> > rcu_sysrq_start();
> > - lockup_detector_suspend();
> > + lockup_detector_soft_poweroff();
> > for (;;);
> > }
>
> Thomas, thanks for cleaning that up.
> You may add to patches 03/04:
> Acked-by: Helge Deller <deller@gmx.de>
>
>
> On a side-note, there is sadly no general function like
> turn_off_all_kind_of_runtime_hang_detectors()
> which turns off *all* detectors at once (including soft lockup detector).
> I've seen another detector complaing at runtime that we were hanging
> here. I would need to dig up more info if you are interested...
There are numerous detectors I have seen over the years: rcu, clocksource,
hard/soft, hang, fs, network, wq?, etc.. I am not sure it is easy to put
them all in one place or makes sense.
I know working with the kvm folks, when they swap back in, the real clock
can do a massive jump forward and causes a flood of warnings such that they
had to 'touch' all of them before running the vm again.
Cheers,
Don
^ permalink raw reply [flat|nested] 4+ messages in thread
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[not found] <20170912193654.321505854@linutronix.de>
2017-09-12 19:36 ` [patch V2 03/29] lockup_detector: Provide interface to stop from poweroff() Thomas Gleixner
2017-09-12 19:36 ` [patch V2 04/29] parisc: Use lockup_detector_stop() Thomas Gleixner
2017-09-14 8:59 ` Helge Deller
2017-09-14 13:46 ` Don Zickus
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