Here's my backtrace for the same problem (thanks, t/t/l!)

trace: pid 22946  at 0xcb8ff6ec
sleepq_block(c03be130,14,cd56efa4,c034ad8e,0) at netbsd:sleepq_block+0x13e
ltsleep(cd56efa4,14,c034ad8e,0,cd56efa4) at netbsd:ltsleep+0xa0
acquire(0,600,c019bd13,cd56efa4,cac92028) at netbsd:acquire+0xd0
lockmgr(cd56efa4,10002,cd56ef34,c03baab4,cbc084a0) at netbsd:lockmgr+0x69f
ufs_lock(cb8ff850,0,0,c0225ffe,0) at netbsd:ufs_lock+0x2b
VOP_LOCK(cd56ef34,10002,cb8ff95c,c0199b7a,cd56ef34) at netbsd:VOP_LOCK+0x23
vn_lock(cd56ef34,10002,0,ffffffff,1691e) at netbsd:vn_lock+0x7c
vget(cd56ef34,10002,0,1000,ffffffff) at netbsd:vget+0x90
ufs_ihashget(4,1691e,0,2,c13dd204) at netbsd:ufs_ihashget+0x7e
ffs_vget(c13e2000,1691e,0,cb8ffa14,c13e2000) at netbsd:ffs_vget+0x2f
ufs_lookup(cb8ffa4c,10002,cbc084a0,cb8ffbec,c13e2000) at netbsd:ufs_lookup+0x7f6
VOP_LOOKUP(cbc084a0,cb8ffbd8,cb8ffbec,cbec3c00,20) at netbsd:VOP_LOOKUP+0x29
lookup(cb8ffbc8,20002,400,cb8ffbe0,c13e2000) at netbsd:lookup+0x1e7
namei(cb8ffbc8,805be58,64,0,3caef8) at netbsd:namei+0x131
sys__lstat30(other stuff I don't wanna type)
syscall_plain()
--- syscall (number 389) ---

and for show vnode cd56ef34:
OBJECT 0xcd56ef34: locked=0, pgops=0xc038edec, npages=0, refs=3

VNODE flags 80<LOCKSWORK>
mp 0xc13e2000 numoutput 0 size 0x200
data 0xcd56d720 usecount 3 writecount 0 holdcnt 0 numoutput 0
tag VT_UFS(1) type VDIR(2) mount 0xc13e2000 typedata 0x0