FreeBSD 6 vs 8.1

[Mats Lindberg]

All
I am migrating from FreeBSD 6.3 to FreeBSD 8.1 And I have noticed some, what
I think is, strange behaviour.

In FreeBSD 6.3 when I do
> swapoff -a
> dd if=/dev/zero of=/tmp/whatever bs=1G count=1

I get something like "out of memory - killed"

In FreeBSD 8.1 doing the same - processes around start to die, e.g. all
getty's are killed and finally devfs goes the same way.

My target is diskless nfs mounted to a linux fileserver - hence no swap
partition
It does not seem to be relalted to the nfs root however - I get the same
behaviour running FBSD-8.1 in a VMWARE server session.

Is this a new 'feature' of FBSD or just a bug?
Are there some sysctl's to set to 'really' turn of swapping.

At one instance I also got a kernel panic saying 'page fault in kernel' but
I'm having a hard time to repeat just that.

regards
Mats