6.2-amd64 Hang at reboot on Supermicro X7DBR-i+

[Guy Helmer]

(reposting since this involves 6-stable)

I'm investigating a problem where a pretty much stock 6.2 SMP kernel 
randomly hangs on multiple Supermicro X7DBR-i+ and X7DBR-8+ systems. The 
system syncs the filesystems and prints "Uptime: ...", then hangs.

So far, I've narrowed it down to the MOD_SHUTDOWN request to the 
"rootbus" module. Adding a printf() before and after the
"device_shutdown(child);" line in subr_bus.c method 
bus_generic_shutdown() seems to make the problem go away, as does 
running a kernel with INVARIANTS, WITNESS, and DDB/KDB. I'm trying to 
reproduce the hang on a plain SMP kernel with just DDB/KDB, but it 
hasn't hung yet.

Any ideas?

Guy

-- 
Guy Helmer, Ph.D.
Chief System Architect
Palisade Systems, Inc.