This is what shows up when I tail /kern/msgbuf on my devel box which  
is running MPACPI on a single processor machine

pool_cache_get(PR_WAITOK) with held simple_lock 0xd88853b4 CPU 0 /usr/ 
src/sys/uvm/uvm_fault.c:903
pool_cache_get_paddr(c087af60,2,0,d18a7938,1) at  
netbsd:pool_cache_get_paddr+0x177
namei(d18a7e04,ffffffff,0,4,0) at netbsd:namei+0x42a
vn_open(d18a7e04,302,180,ce3c0360,989680) at netbsd:vn_open+0x6d
coredump(ce3cbe70,c08151c0,585,202,c0815074) at netbsd:coredump+0xe0
sigexit(ce3cbe70,b,4002,b,0) at netbsd:sigexit+0x75
postsig(b,d18a7f54,0,1,1) at netbsd:postsig+0x2a2
trap() at netbsd:trap+0x3e8
--- trap (number 6) ---
0x8049439:
Stopped in pid 24825.1 (tail) at netbsd:cpu_Debugger+0x4: leave

Doing this on a physically multiprocessor box hangs the machine.