Re: is killing zombies possible w/o a reboot?

[Denis Vlasenko]

On Thursday 04 November 2004 01:33, Russell Miller wrote:
> On Wednesday 03 November 2004 17:03, Doug McNaught wrote:
> 
> > It was already mentioned in this thread that the bookkeeping required
> > to clean up properly from such an abort would add a lot of overhead
> > and slow down the normal, non-buggy case.
> >
> I am going to continue pursuing this at the risk of making a bigger fool of 
> myself than I already am, but I want to make sure that I understand the 
> issues - and I did read the message you are referring to.
> 
> I think what you are saying is that there is kind of a race condition here.  
> When something is on the wait queue, it has to be followed through to 
> completion.  An interrupt could be received at any time, and if it's taken 
> off of the wait queue prematurely, it'll crash the kernel, because the 
> interrupt has no way of telling that.

The problem is in locking. You must not kill process while it is
in uninterruptible state because it is uninterruptible
for a reason - has taken semaphore, or get_cpu(), etc.
You do want it to do put_cpu(), right?

Processes must never get stuck in D, it's a kernel bug.

Find out how did process ended up in D state forever,
and fix it - that's what I'm trying to do
in these cases.
--
vda

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