VIMAGE: Freed UMA keg was not empty

Hello,

We are using FreeBSD + VIMAGE at work, and we have seen an annoying problem : 
there seems to be a memory leak in the kernel, which eventually causes a 
panic.

(yes, we have seen the following message : "WARNING: VIMAGE (virtualized 
network stack) is a highly experimental feature.")

Configuring a network interface in a jail with vnet enabled, then removing
that jail causes these messages. In dmesg:

[...]
Freed UMA keg was not empty (203 items).  Lost 1 pages of memory.
Freed UMA keg was not empty (36 items).  Lost 2 pages of memory.

The issue happens in a GENERIC FreeBSD 8.1 kernel, with VIMAGE enabled (with 
attached VIMAGE kernel config file).

The following commands reproduce the bug:

jail -l -u root -c path=/ name=foo persist vnet &&
jexec foo ifconfig lo0 127.0.0.1/8 &&
jail -r foo

Running it too many times exhausts kernel memory and crashes the machine.

The probleme is seen on 8.1-release kernel, 8-stable from SVN and SVN -head.

Attachments: dmesg log and kernel config.

	cheers

	Thierry Herbelot