pmap_fault: PT2MAP abort on rpi2 while building world

[bob prohaska]

Several times now buildworld attempts have crashed with
 pmap_fault: PT2MAP abort.

It started several weeks ago and has been happening intermittently
ever since. So far it's only occurred during buildworld, not other
compilations such as firefox (which still fails from porting issues).

I couldn't find any recent posts on this error, is it worth a bug
report?

The information I could gather from the latest crash is at
http://www.zefox.net/~fbsd/rpi2/crashes/crash_9_20_17/

Thanks for reading, and any guidance!

bob prohaska