vm_thread_new: kstack allocation failed with vm.kmem_size="1536M"

[Pete French]

> I'm running 7-STABLE as of Feb 26 or so.  Commit r187466 on Jan 20 bumped up
> kmem_size_max on amd64 to 3.6GB:
>
> http://svn.freebsd.org/viewvc/base?view=revision&revision=187466

Mmmmm.... now I am wworried about upgrading to STABLE! ;) I can't
think of a reason why I am seeing what I am seeing - on 7.1-RELEASE
I am certainly icreasing the limits not decreasing them, yet I
am seeing it running out of memory on the larger limit.

Note that these machines have no swap - but then since the system runs fine
on a 4gig machine with 4 gig of sap, I made the assumption that if
the machine was expanded to 8 gig of real memory it no longer needs the
swap, as it now has as much real RAM in it as real+swap was before.

-pete.