so, no way to kill process? have to reboot?

so, no way to kill process? have to reboot?

[Christopher Friesen]

Well, the unkillable process continues on.  Does nobody else have any ideas on
how to kill an unkillable process in the R state thats sucking up all my unused
cpu cycles?

If not I'm going to have to reboot this thing...

Chris

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Re: so, no way to kill process? have to reboot?

[James Sutherland]

On Thu, 11 Oct 2001, Christopher Friesen wrote:

> Well, the unkillable process continues on.  Does nobody else have any ideas on
> how to kill an unkillable process in the R state thats sucking up all my unused
> cpu cycles?
>
> If not I'm going to have to reboot this thing...

Short term hack: renice it to 20, so it doesn't interfere with normal
workload. Also try sending it a SIGSTOP, although I doubt that will work
here. I think strace will fail the same way gdb does, but try that too...


James.
-- 
"Our attitude with TCP/IP is, `Hey, we'll do it, but don't make a big
system, because we can't fix it if it breaks -- nobody can.'"

"TCP/IP is OK if you've got a little informal club, and it doesn't make
any difference if it takes a while to fix it."
		-- Ken Olson, in Digital News, 1988

Re: so, no way to kill process? have to reboot?

[Paul Mackerras]

Christopher Friesen writes:

> Well, the unkillable process continues on.  Does nobody else have any ideas on
> how to kill an unkillable process in the R state thats sucking up all my unused
> cpu cycles?

I would suspect that it is actually looping inside the kernel, which
would mean that there indeed was no way to kill it.  You could try
alt-scrolllock on the console and see if you get a register dump of
it, or maybe one of the alt-sysrq magic keys might give you some
information.  But I suspect that rebooting is ultimately going to be
your only solution.

Paul.

Re: so, no way to kill process? have to reboot?

[Terje Eggestad]

fre, 2001-10-12 kl. 08:16 skrev Paul Mackerras:
    Christopher Friesen writes:
    
    > Well, the unkillable process continues on.  Does nobody else have any ideas on
    > how to kill an unkillable process in the R state thats sucking up all my unused
    > cpu cycles?
    
    I would suspect that it is actually looping inside the kernel, which
    would mean that there indeed was no way to kill it.  You could try
    alt-scrolllock on the console and see if you get a register dump of
    it, or maybe one of the alt-sysrq magic keys might give you some
    information.  But I suspect that rebooting is ultimately going to be
    your only solution.
    
You might find out if it's looping inside the kernel by doing strace -p
<pid>, if you're stuck in a syscall, I *belive* strace'll tell you.

You wouldn't by any chance be developing a kernel module??

    Paul.
    
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Re: so, no way to kill process? have to reboot?

[Peter Wächtler]

Christopher Friesen wrote:
> 
> Well, the unkillable process continues on.  Does nobody else have any ideas on
> how to kill an unkillable process in the R state thats sucking up all my unused
> cpu cycles?
> 
> If not I'm going to have to reboot this thing...
> 

Well, I'd suspect it in "D" state - waiting for some disk I/O to
finish...

But in "R" with your described behavior looks like a bug.
If you care about the CPU time waisted: what about kill -STOP <pid>?

Can you describe your filesystem layout?
I think of a symlink recursion bug or something wrong in /dev/shm
or alike... (no flame, just guessing :)

What are the parameters of "find"?

Ability to kill (was: Re: so, no way to kill process? have to reboot?)

[vda]

PW> Well, I'd suspect it in "D" state - waiting for some disk I/O to
PW> finish...

If a process is stuck in D state it's a kernel bug - I
don't think it's ever legitimate to wait forever for something
which could never happen. However, some such bugs are rarely
happening (e.g. a swapin failure due to hdd malfunction)
and thus will unlikely be fixed.

PW> But in "R" with your described behavior looks like a bug.
PW> If you care about the CPU time waisted: what about kill -STOP <pid>?

R state unkillable hang is possible too (infinite loop in kernel
preventing return from a syscall).

In short, in my understanding any syscall should return sooner
or later in order to process to be killable. Anything preventing
that is a kernel bug.

However, I'm not a UNIX guru, I may be wrong.
I really like to be enlightened if I'm wrong.
-- 
Best regards, vda
mailto:vda@port.imtp.ilyichevsk.odessa.ua

Re: so, no way to kill process? have to reboot?

[Christopher Friesen]

"Friesen, Christopher [CAR:3R60:EXCH]" wrote:

Well, I've rebooted the thing.

It appears that whatever it was looping on was in the kernel.  I suspect that it
has something to do with NFS--this is a 2.2.17 kernel and we ran into some
issues with it and NFS on some other systems.

Thanks for the help guys...unfortunately I rebooted before getting the messages
about checking in /proc--it would have been interesting to see what it was
doing.

Chris

-- 
Chris Friesen                    | MailStop: 043/33/F10  
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