Nouveau - Jun 2013 - [Bug 65554] New: CPU lock with nouveau_fan_update

https://bugs.freedesktop.org/show_bug.cgi?id=65554

          Priority: medium
            Bug ID: 65554
          Assignee: nouveau at lists.freedesktop.org
           Summary: CPU lock with nouveau_fan_update
        QA Contact: xorg-team at lists.x.org
          Severity: major
    Classification: Unclassified
                OS: Linux (All)
          Reporter: ddamienn at gmail.com
          Hardware: Other
            Status: NEW
           Version: unspecified
         Component: Driver/nouveau
           Product: xorg

Created attachment 80540
  --> https://bugs.freedesktop.org/attachment.cgi?id=80540&action=edit
kernel log

Kernel logs report "Watchdog detected hard LOCKUP on cpu 1". It has
occurred
once per day for the last three days. Each time, it happens seemingly randomly
- monitor is turned off, I'm connected remotely via SSH but system is idle.

This is on ArchLinux with xf86-video-nouveau 1.0.7. The machine is ~2.5 years
old and has been very solid until now. My video card is: 01:00.0 VGA compatible
controller: NVIDIA Corporation GT216 [GeForce GT 220] (rev a2).

I have attached the kernel log. I also note that I don't know why the
'PTHERM'
events would be occurring - this was while the connected monitor was off and I
was only connected remotely via SSH.

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--- Comment #1 from Ilia Mirkin <imirkin at alum.mit.edu> ---
nouveau_fan_update:
    spin_lock_irqsave(&fan->lock, flags);
    /* schedule next fan update, if not at target speed already */
    if (list_empty(&fan->alarm.head) && target != duty) {
        u16 bump_period = fan->bios.bump_period;
        u16 slow_down_period = fan->bios.slow_down_period;
...
        ptimer->alarm(ptimer, delay * 1000 * 1000, &fan->alarm);

If delay is somehow 0, the ->alarm will cause nouveau_fan_update to get
called
immediately. Can you add a printk to that function that shows the values? (This
may end up totally flooding your dmesg too... but I think the values may be the
same across prints.)

e.g.

diff --git a/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c
b/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c
index c728380..9453afd 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/therm/fan.c
@@ -88,7 +88,7 @@ nouveau_fan_update(struct nouveau_fan *fan, bool immediate,
int target)
                        delay = min(bump_period, slow_down_period) ;
                else
                        delay = bump_period;
-
+               nv_info(therm, "Scheduling fan update in %d (slow: %d,
bump:
%d)\n", delay, slow_down_period, bump_period);
                ptimer->alarm(ptimer, delay * 1000 * 1000,
&fan->alarm);
        }

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--- Comment #2 from ddamienn at gmail.com ---
(In reply to comment #1)
> If delay is somehow 0, the ->alarm will cause nouveau_fan_update to get
> called immediately. Can you add a printk to that function that shows the
> values? (This may end up totally flooding your dmesg too... but I think the
> values may be the same across prints.)
Thanks for your help. I will try to add the printk. The lock has made the
machine inaccessible remotely, so it'll be a couple of days until I can post
the results.

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ddamienn at gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |INVALID

--- Comment #3 from ddamienn at gmail.com ---
I've had the debug statement active for the last few days, but the error
hasn't
re-occurred. I discovered that my video card's fan was only working
intermittently, which a clean seems to have fixed. Since the inactive fan
likely caused the error I was seeing, I am closing this bug report as invalid.

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