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RE: [Xen-devel] segfault in VM

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: RE: [Xen-devel] segfault in VM
From: James Harper <JamesH@xxxxxxxxxxxxxxxx>
Date: Wed, 21 Jul 2004 11:14:48 +1000
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Thread-topic: [Xen-devel] segfault in VM
I downloaded these (from a tgz that Keir had given me a link to as bk was down - I assume it's identical to his latest fixes) and started my tests running and went to bed, but it looks like I got errors within a very short time.
The tests I was running were my 'compare' script and pinging the two domains I had running with
ping -q -i 0.01 -s 1400 <ip address>
 
Lots of oopses in the logs, most are probably as a result of the corruption and not indicative of the cause. They look similar to Jody's dump so I won't bother sending them unless someone thinks they might be useful.
 
btw, can the install be modified to give us a System.map-2.4.26-xen[0U] in /boot? ksymoops would be much happier.
 
James
 


From: Keir Fraser
Sent: Tue 20/07/2004 8:52 PM
To: Keir Fraser
Cc: James Harper; xen-devel@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] segfault in VM

I've checked in some more fixes that might entirely solve the problems
that everyone has been seeing.

Unfortunately xen.bkbits.net is down and I'm about to leave for
Canada. :-( Hopefully it will be possible to push to bkbits in a few
hours... 

The Changesets that will hopefully fix everything are:
   1.1116 04/07/20 11:32:39 kaf24@xxxxxxxxxxxxxxxxxxxxx +2 -0
   More backend driver fixes and robustifying.

   1.1115 04/07/20 11:14:24 kaf24@xxxxxxxxxxxxxxxxxxxxx +0 -0
   Merge scramble.cl.cam.ac.uk:/auto/groups/xeno/BK/xeno.bk
   into scramble.cl.cam.ac.uk:/local/scratch/kaf24/xeno

So keep an eye out for these when you pull --- we're very interested
to hear of further bugs in builds /with/ these changesets. :-)

 -- Keir

> I've just checked in a few networking fixes that should make things
> rather more robust in low-memory conditions. I suspect there are still
> some bugs lurking somewhere, but hopefully this has thinned out the
> bugs somewhat.
> 
>  -- Keir
> 
> > bk pull only showed 2 patches, neither of which affected kernels so
> > I didn't bother recompiling.
> > 
> > I have seen an error (shown by my diff script 'compare' or by xend
> > doing silly things like crashing), by simply starting another domain
> > and pinging it with something like:
> > 
> > ping -s 1400 -i 0.001 192.168.200.200
> > 
> > (ping -f might do it but I think it goes a bit fast)
> > 
> > That occured once after about 5 minutes, but then not again for the 10 or so minutes I left it running.
> > 
> > running it out of memory with this code:
> > 
> > #include <stdio.h>
> > #include <stdlib.h>
> > int main() {
> >         char *buf;
> >         int mem = 0;
> >         int size = 1;
> >         char rnd;
> >         rnd = rand() & 255;
> >         while(1) {
> >                 buf = (char *)malloc(size*1024*1024);
> >                 memset(buf, rnd, size*1024*1024);
> >                 if (buf != NULL) {
> >                         mem += size;
> >                         printf("%d\n", mem);
> >                 }
> >         }
> > }
> > 
> > causes a crash far more quickly. I guess it's possible that those are two different errors though...
> > 
> > James
> 
> 
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