[clug] What causes an unkillable process?

[Martijn van Oosterhout]

On Sun, Nov 23, 2008 at 04:11:27AM -0800, Jason Stokes wrote:
> The following process: 
> 
> > 10685 jason     20   0  143m 8500 8492 D 64.9  1.6 937:50.21 totem              
> 
> Won't die with kill -9, not even as root.  Sure, I can just reboot, but I'm wondering what on earth causes such a thing.

D state is unkillable. It means it's stuck in the kernel somewhere. I
thought there was a way to find out exactly where, but I can't remember
how. One of the sysrq commands?

The most common causes are disk access, reading/wrting from a stuck NFS
mount, broken hard disk, etc.

Once it gets out of the kernel the process will be killed before it
reaches userspace. So it's just a matter of finding out where it's
stuck. 

Oh yes, kernel bugs can cause this too :)

Have a niec day,
-- 
Martijn van Oosterhout   <kleptog at svana.org>   http://svana.org/kleptog/
> Please line up in a tree and maintain the heap invariant while 
> boarding. Thank you for flying nlogn airlines.
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