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Subject: Re: NULL dereference in clockevents_program_event
From: Johannes Berg <johannes@sipsolutions.net>
To: Thomas Gleixner <tglx@linutronix.de>
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Date: Wed, 28 Nov 2007 00:52:20 +0100
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> During a hibernate cycle on my G5, while machine was powering down after
> saving the image, I just had a NULL dereference  in
> clockevents_program_event when accessing dev->mode, dev was NULL.
>=20
> Unfortunately the machine rebooted before I was able to write down more
> than the fact that it was called from tick_program_event(); the problem
> doesn't seem to be easily reproducible.
>=20
> From what I can see when doing the same thing, the shutdown attempts to
> offline all CPUs. Because the snapshot was actually saved to disk and
> the machine was shutting down I guess that the it happened at that time,
> but I have no idea what else to do to debug this.
>=20
> I have
>=20
> | CONFIG_HIGH_RES_TIMERS=3Dy
> | CONFIG_NO_HZ=3Dy
>=20
> in this config.

I just got the same or a similar thing again and was able to write down
more of the stack dump:

NIP clock_events_program_event+0x20
LR  tick_program_event+0x64
Stack:
hr_timer_interrupt+0x211
timer_interrupt+0xc4
decrementer_common+0x110

johannes

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