[uml-devel] UML hanging while deactivating swap

[uml-devel] UML hanging while deactivating swap

[Sven Köhler]

Hi,

ubd1 of my UML is a swapfs, and when halting or rebooting it, it hangs 
while the swap is deactivated (i guess swapoff -a is executed).

I'm using 2.6.6-um1

Thx
   Sven



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Re: [uml-devel] UML hanging while deactivating swap

[Jeff Dike]

skoehler@upb.de said:
> ubd1 of my UML is a swapfs, and when halting or rebooting it, it hangs
>  while the swap is deactivated (i guess swapoff -a is executed). 

Can you narrow it down within the shutdown process?  Adding -x to the #!
lines of the relevant scripts is a good way to do this.

Also, can you get a stack trace from UML?

				Jeff



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Re: [uml-devel] UML hanging while deactivating swap

[Sven Köhler]

>>ubd1 of my UML is a swapfs, and when halting or rebooting it, it hangs
>> while the swap is deactivated (i guess swapoff -a is executed). 
> 
> Can you narrow it down within the shutdown process?  Adding -x to the #!
> lines of the relevant scripts is a good way to do this.

the relevant lines of the init script are

if [ -n "`swapon -s 2>/dev/null`" ]
then
         ebegin "Deactivating swap"
         swapoff -a &>/dev/null
         eend $?
fi

so it _must_ be the "swapoff -a" since i see the "Deactivating swap" 
message, but not the "OK" that eend would generate.

> Also, can you get a stack trace from UML?

I don't know how to do that, sorry :-(. I have never worked with gdb and 
suchlike, but i'd really like to help to track the error down somehow.

The UML seems to be still running, since it takes CPU-time on the host, 
but the swapoff seems to never return.

It also hard for me to reproduce this, but i think it only happens when 
swap is used. If i try to reproduce it by running some programs that use 
much memory and therefor things get swapped, the UML halts without 
problems. Other UMLs that ran for months and have about 1MB swap used 
hang while the swap gets deactivated.




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Re: [uml-devel] UML hanging while deactivating swap

[BlaisorBlade]

On Friday 10 September 2004 05:11, Sven Köhler wrote:
> >>ubd1 of my UML is a swapfs, and when halting or rebooting it, it hangs
> >> while the swap is deactivated (i guess swapoff -a is executed).
> >
> > Can you narrow it down within the shutdown process?  Adding -x to the #!
> > lines of the relevant scripts is a good way to do this.
>
> the relevant lines of the init script are
>
> if [ -n "`swapon -s 2>/dev/null`" ]
> then
>          ebegin "Deactivating swap"
>          swapoff -a &>/dev/null
>          eend $?
> fi
>
> so it _must_ be the "swapoff -a" since i see the "Deactivating swap"
> message, but not the "OK" that eend would generate.

No, the message could be generated but the console not flushed.

However, I think you should manually comment out the "swapoff" line and retry. 
You will maybe discover that is not a fix. Someone else had problems with 
hwclock, instead, so you try this, too.

> > Also, can you get a stack trace from UML?
>
> I don't know how to do that, sorry :-(. I have never worked with gdb and
> suchlike, but i'd really like to help to track the error down somehow.
>
> The UML seems to be still running, since it takes CPU-time on the host,
> but the swapoff seems to never return.
>
> It also hard for me to reproduce this, but i think it only happens when
> swap is used. If i try to reproduce it by running some programs that use
> much memory and therefor things get swapped, the UML halts without
> problems. Other UMLs that ran for months and have about 1MB swap used
> hang while the swap gets deactivated.
Could it be because there is not enough free memory to free the swap?

-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729


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