System hanging during dump

[Alfred Perlstein]

* heliocentric at gmail.com <heliocentric at gmail.com> [081015 12:00] wrote:
> 
> Perhaps a 'show locks' with an 8-CURRENT kernel with WITNESS enabled
> will shed light on the problem? As most of the filesystem locking
> doesn't use lockmgr in 7-STABLE, it would be silent with that kernel.

I might be wrong here, but I think it's actually that lockmgr
in 7.x isn't watched by witness (but it is in 8.x) is why you
can only see this warnings in 8.x.

(In other words, filesystems use lockmgr in just about every version
of FreeBSD back to 2.x or before.)

-Alfred