compcache locks the system; Was: Swap problems

[email.listen at googlemail.com]

On Sat, 7. February 2009 21:37:48 email.listen at googlemail.com wrote:
> On Fri, 6. February 2009 12:30:55 Dake K. Odzangba wrote:
> > Hello, I do not have a swap partition (or file) because I've got 2GB of
>
> physical ram. Yet the output of free tells me:
> > >              total       used       free     shared    buffers    
> > > cached Mem:       2064336    1986368      77968          0      54092  
> > >   456332 -/+ buffers/cache:    1475944     588392
> > > Swap:       516080     377168     138912
> >
> > And when I examined my logs I found this:
[...]
> > > Feb  6 11:08:28 mal-zeth kernel: >[1562156248.450441]66248.450473]
> > > c448.450757] co..450789] comp550821] compcac8854] compc75] compcache:
> > > compcache:rompcache: Errotpcache: Err-ache: Error rhe: Error alloo:
> > > Error a Error allorror allo or allocati allocatingpllocating medocating
> > > memoating memory ing memory for g memory fomemory for c4mory for co0ry
> > > for compressed
> > >
> > > 8 for compress1or compresse8 compressed p)ompressed pag<pressed page:
> > > >essed page: 101sed page: 1036d page: 1034page: 103968, si.ge: 1034e:
> > >
> > > 103970, 1 103971, 9103972, 03973, siz]974, si 75, sizec6, size=28
> >
> > This doesn't look good... any ideas?
>
> Yes, I've also seen this on one of my machines.
>
> The problem is compcache  which maps ram as swapspace (ramdisk).
> I saw this first when this machine got totaly locked. Only rebooting with a
> hard reset by pressing poweroff helped.
>
> You will see this when you run in a terminal:
>
>     sudo swapon -s
>
> The output will show the memory allocated by compcache.
>
> or
>
>     sudo lsmod | grep compcache
>
> The output will show that compcache, lzo_decompress and lzo_compress
> modules are loaded.
>
> The solution is to disable compcache:
>
>     sudo swapoff -a
>     sudo swapon -a
>
> You may also unload all modules after you disabled compcache loaded by
> compcache and compcache itself:
>
>     sudo rmmod compcache
>     sudo rmmod lzo_decompress
>     sudo rmmod lzo_compress
>
>
> regards,
> thomas

Pardon me, I forgot to cut you long list of output in my previous email.


The following little script may be helpfull:

---8<--- swapreset ---8y---
#!/bin/bash
#
#     Filename : swapreset
#      Version : 0.1
#         Date : 07-feb-09
#       Author : email.listen at gmail.com
# Last changed :  07-feb-09
#
#      Options : none-yet
#        Usage : swapreset
#                

## test for compcache
## if yes reset swap and remove compcache and it's child kernel modules
if [ "$(lsmod|grep compcache)"  ] ; then
	## restarting swap, 
	## compcache will _not_ restart
	echo -e "currently aktive swap partitions:"\n
	echo -e "--------------------------------"\n
	sudo swapon -s
	echo -e "will now reset swap partitions"\n
	sudo swapoff -a
	sudo swapon -a
	echo -e "--------------------------------"\n
	echo -e "finally aktive swap partitions:"\n
	sudo swapon -s
	sudo rmmod compcache
	sudo rmmod lzo_decompress
	sudo rmmod lzo_compress
else
	echo -e "no compcache loaded! \nnothing to do so far."
fi

---8<--- swapreset ---8y---

Save this file to a users $HOME/bin/ directory who has sudo privileges.


Make it executable with:

    sudo chmod 700 swapreset

Start it and compcache is disabled.


regards,
thomas
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