I had this happen to me on the mac68k port for a couple weeks, on a 
kernel built from March 3 sources.  I rebuilt yesterday (March 16) and 
the problem has disappeared.

There were several recent (last few weeks) changes to the vm system, and I 
_think_ that's where the problem came from.

On Mon, 17 Mar 1997, Jonathan Stone wrote:

> 
> Kernels I built for a NetBSD/pmax snapshot seem to repeatably hang
> processes when I type "sync".  This causes shutdown and reboot to
> fail.  reboot -n, however, works.  This happened for kernels built
> from march 14/15 source.  It didn't happen for kernels built on march
> 5 from March 4 sup source.
> 
> I only have FFS and NFS filesystems mounted.  ps shows that update
> and any sync processes are waiting on "thrd_s" (thread_sleep?)
> 
> Has anyone seen anything similar on this or any other platform?  I
> haven't touched any of the pmax kernel in some time. I've also
> upgraded the version of GNU ld I'm using, but pmax kernels are still
> linked with a binutils-2.6 kernel, so I don't see anything
> port-specific thats' changed.  I tend to blame some of the recent VM
> changes, but it's just a guess.
> 
> thanks
> --Jonathan
> 
> (ps: can we either limit waitchannel names to something that fit in
> ps's "WCHAN" column, or fix ps -awwl to print the entire waitchannel
> name?)
> 

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