Proc leak in -current (yesterdays)

I have been stress testing an SMP kernel from yesterday..

After a couple of buildworlds I have noticed that we are losing proc
structs..

the number of allocated proc structs can be seen by:

sysctl vm.zone|grep PROC

the number of processes active can be seen from
ps aux|grep wc.

After a single run ofn "make buildworld", I have 60
processes active but vm.zone shows that it has 117 proc structures
outstanding. After a few rounds of "make buildworld"
it was at 250 proc structures outstanding..

Anyone else seen this?