VIMAGE: Freed UMA keg was not empty

[Bjoern A. Zeeb]

On Wed, 17 Nov 2010, Thierry Herbelot wrote:

Hi,

>> The problem has been present since day 1 and is still present up to
>> HEAD.  This is about type stability and teardown.  So far we are no
>> able to actually free TCP (and UDP in SVN) states as they might still
>> be accesses after "free".  It's a general problem in the network stack
>> and has been implemented as a measure to circumvent panics in those
>> cases.
>>
>> I am not sure if that's actually what's biting you wrt to memory or
>> if it's something else.  Unfortunately boot logs and kernel configs
>> don't help much; enable ddb and get show uma and show malloc reports
>> after the crash (or watch vmstat -z and vmstat -m) after every 50 jail
>> restarts.  I might have some patches for a couple of things but cannot
>> (yet) help with the additional (duplicate) UMA zones showing up at
>> each iteration (for the -z case).
>
> The context for our problem is that VIMAGE jails are mant to be used "in
> production" for automated tests, thus are likely to be multiple on one
> physical host, and are likely to be started and stopped according to our
> needs.
>
> We have tried more "classical" virtualization solutions (qemu, kvm, ... ,
> normal jails with individual FIBs, ...) but only FreeBSD with VIMAGE seems to
> be the correct answer. (for other reasons, an i386 version of the kernel must
> be used)
>
> The point of my original email was to simplify the configuration for a test
> setup : any machine with the attached configuration file and the above
> sequence of commands creating and deleting jails, running in a loop, will
> eventually panic.

The thing you can do is start the jails persistent and then only
garbage collect proceses and network configuration manually and
reconfigure/restart things for the next iteration;  you might still
leak network stack details between runs but if that's not a problem
for you the solution might work.

Regards,
Bjoern

-- 
Bjoern A. Zeeb                              Welcome a new stage of life.
         <ks> Going to jail sucks -- <bz> All my daemons like it!
   http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/jails.html