2002-04-10 12:54:01

by Duncan Sands

[permalink] [raw]
Subject: 2.5.8-pre2: preempt: exits with preempt_count 1

My system (x86 K6 UP running 2.5.8-pre2 with preemption) on powering down
gave:

...
Power down.
error: halt[411] exited with preempt_count 1

This was after about 24 hours of up time. What can I do to help
track down this locking problem?

All the best,

Duncan.


2002-04-10 18:28:15

by Robert Love

[permalink] [raw]
Subject: Re: 2.5.8-pre2: preempt: exits with preempt_count 1

On Wed, 2002-04-10 at 08:53, Duncan Sands wrote:

> error: halt[411] exited with preempt_count 1
>
> This was after about 24 hours of up time. What can I do to help
> track down this locking problem?

It is not a big deal. The issue is that in the system shutdown code,
something does not release a lock but just figures "the system is going
down, what is the point?" It is probably the BKL ...

For the sake of code readability and having nothing quit with a nonzero
preempt_count, we should explicitly drop the lock, but it is not hurting
anything (now, if you get this message elsewhere, there may be a
problem).

I am trying to find what is the cause but I have not tracked it down yet
...

Robert Love

2002-04-10 18:39:29

by Skip Ford

[permalink] [raw]
Subject: Re: 2.5.8-pre2: preempt: exits with preempt_count 1

Duncan Sands wrote:
> My system (x86 K6 UP running 2.5.8-pre2 with preemption) on powering down
> gave:
> ...
> Power down.
> error: halt[411] exited with preempt_count 1
>
> This was after about 24 hours of up time. What can I do to help
> track down this locking problem?

If you fixed the oopsing 2.5.8-pre1 kernel by putting 'lock_kernel()'
in exit.c, then you have to remove that line.

The correct fix was applied later, and if you leave in the call
to 'lock_kernel()' you get the exact message you're reporting.

If line 505 of kernel/exit.c is lock_kernel() in your tree then delete
it, and try again.

--
Skip

2002-04-10 18:44:10

by Pierre Rousselet

[permalink] [raw]
Subject: Re: 2.5.8-pre2: preempt: exits with preempt_count 1

Robert Love wrote:
> On Wed, 2002-04-10 at 08:53, Duncan Sands wrote:
>
>
>>error: halt[411] exited with preempt_count 1
>>
>>This was after about 24 hours of up time. What can I do to help
>>track down this locking problem?

Duncan Sands wrote:
> UP x86 K6 system running 2.5.8-pre3 with preemption.
> Using usb-uhci. I got the following bug when powering off:

It looks like one problem, caused by some usb device driver not exiting
cleanly.

Pierre
--
------------------------------------------------
Pierre Rousselet <[email protected]>
------------------------------------------------

2002-04-10 19:20:54

by Duncan Sands

[permalink] [raw]
Subject: Re: 2.5.8-pre2: preempt: exits with preempt_count 1

On Wednesday 10 April 2002 8:40 pm, Skip Ford wrote:
> Duncan Sands wrote:
> > My system (x86 K6 UP running 2.5.8-pre2 with preemption) on powering down
> > gave:
> > ...
> > Power down.
> > error: halt[411] exited with preempt_count 1
> >
> > This was after about 24 hours of up time. What can I do to help
> > track down this locking problem?
>
> If you fixed the oopsing 2.5.8-pre1 kernel by putting 'lock_kernel()'
> in exit.c, then you have to remove that line.
>
> The correct fix was applied later, and if you leave in the call
> to 'lock_kernel()' you get the exact message you're reporting.
>
> If line 505 of kernel/exit.c is lock_kernel() in your tree then delete
> it, and try again.

No, it wasn't that, but thanks for thinking about it.

Ciao, Duncan.

2002-04-10 19:21:38

by Duncan Sands

[permalink] [raw]
Subject: Re: 2.5.8-pre2: preempt: exits with preempt_count 1

On Wednesday 10 April 2002 8:42 pm, Pierre Rousselet wrote:
> Robert Love wrote:
> > On Wed, 2002-04-10 at 08:53, Duncan Sands wrote:
> >>error: halt[411] exited with preempt_count 1
> >>
> >>This was after about 24 hours of up time. What can I do to help
> >>track down this locking problem?
>
> Duncan Sands wrote:
> > UP x86 K6 system running 2.5.8-pre3 with preemption.
> > Using usb-uhci. I got the following bug when powering off:
>
> It looks like one problem, caused by some usb device driver not exiting
> cleanly.

Probably. There was no BUG with 2.5.8-pre2 though.

Duncan.

2002-04-10 21:59:59

by Bongani Hlope

[permalink] [raw]
Subject: Re: 2.5.8-pre2: preempt: exits with preempt_count 1

On Wed, 2002-04-10 at 20:28, Robert Love wrote:
> On Wed, 2002-04-10 at 08:53, Duncan Sands wrote:
>
> > error: halt[411] exited with preempt_count 1
> >
> > This was after about 24 hours of up time. What can I do to help
> > track down this locking problem?
>
> It is not a big deal. The issue is that in the system shutdown code,
> something does not release a lock but just figures "the system is going
> down, what is the point?" It is probably the BKL ...
>
> For the sake of code readability and having nothing quit with a nonzero
> preempt_count, we should explicitly drop the lock, but it is not hurting
> anything (now, if you get this message elsewhere, there may be a
> problem).
>
> I am trying to find what is the cause but I have not tracked it down yet

This is also still happening on 2.4.19-pre6 + preempt


> ...

>
> Robert Love





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2002-04-10 22:07:55

by Chris Wright

[permalink] [raw]
Subject: Re: 2.5.8-pre2: preempt: exits with preempt_count 1

* Robert Love ([email protected]) wrote:
> On Wed, 2002-04-10 at 08:53, Duncan Sands wrote:
>
> > error: halt[411] exited with preempt_count 1
> >
> > This was after about 24 hours of up time. What can I do to help
> > track down this locking problem?
>
> It is not a big deal. The issue is that in the system shutdown code,
> something does not release a lock but just figures "the system is going
> down, what is the point?" It is probably the BKL ...
>
> For the sake of code readability and having nothing quit with a nonzero
> preempt_count, we should explicitly drop the lock, but it is not hurting
> anything (now, if you get this message elsewhere, there may be a
> problem).

ditto with nfs. doesn't require a system shutdown, just stopping the
nfs server.

error: nfsd[983] exited with preempt_count 1
error: rpciod[994] exited with preempt_count 1
error: lockd[993] exited with preempt_count 1

cheers,
-chris