This looks to me like a duplicate of 7003327: Correct test awt/FontClass/CreateFont/DeleteFont
which despite its synopsis is really not a bug in the test at all, rather a change in behaviour
of the VM under bug :
6938627: Make temporary directory use property java.io.tmpdir when specified
which is being undone/revertd under bug ID
7009828: Fix for 6938627 breaks visualvm monitoring when -Djava.io.tmpdir is defined
It started failing in 6u23 because the new hotspot was integrated there.
Maybe best to close it out as a dup of that one (7009828) as that's the
fix that will resolve this failure.