Trap 12 in ufs/uma code

One of the i386 package machines (running current from 9 days ago,
with UFS2 filesystems) panicked with this:

Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0xfe8
fault code              = supervisor read, page not present
instruction pointer     = 0x8:0xc039c56b
stack pointer           = 0x10:0xd8d32690
frame pointer           = 0x10:0xd8d326b4
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 90186 (mtree)
kernel: type 12 trap, code=0
Stopped at      uma_dbg_free+0x4b:      subl    0x10(%esi),%ebx
db> trace
uma_dbg_free(c413a6c0,0,0,6af,0) at uma_dbg_free+0x4b
uma_zfree_arg(c413a6c0,0,0,c58c3510,d8d3271c) at uma_zfree_arg+0x121
ffs_ifree(c4483600,c58c3510,c0439575,9d,0) at ffs_ifree+0x4f
ufs_reclaim(d8d32750,d8d327c0,c02b894f,d8d32750,1) at ufs_reclaim+0xe2
ufs_vnoperate(d8d32750,1,0,c45a1ab0,0) at ufs_vnoperate+0x18
vclean(c5e2eb68,8,c45a1ab0,c5e2eb68,0) at vclean+0x2ef
vgonel(c5e2eb68,c45a1ab0,c042cc76,a6d,c5e2eb68) at vgonel+0x5c
vrecycle(c5e2eb68,0,c45a1ab0,52,c0496428) at vrecycle+0x6b
ufs_inactive(d8d32868,d8d32894,c02b7f17,d8d32868,0) at ufs_inactive+0x23c
ufs_vnoperate(d8d32868,0,c042cc76,8c4,c047f120) at ufs_vnoperate+0x18
vput(c5e2eb68,31e3c40,0,4000,0) at vput+0x137
ffs_vget(c413cc00,31f43d,2,d8d3298c,d8d32990) at ffs_vget+0x310
ufs_lookup(d8d32ab8,d8d32af4,c02abb7c,d8d32ab8,d8d32c38) at ufs_lookup+0xce5
ufs_vnoperate(d8d32ab8,d8d32c38,d8d32c4c,c45a1ab0,c45a1ab0) at ufs_vnoperate+0x18
vfs_cache_lookup(d8d32b68,d8d32b94,c02b07a2,d8d32b68,20002) at vfs_cache_lookup+0x2fc
ufs_vnoperate(d8d32b68,20002,c45a1ab0,3,c45a1ab0) at ufs_vnoperate+0x18
lookup(d8d32c24,0,c042c576,a4,c45a1ab0) at lookup+0x302
namei(d8d32c24,0,c04a0020,0,0) at namei+0x24e
lstat(c45a1ab0,d8d32d10,c0440774,3fb,2) at lstat+0x52
syscall(2f,2f,2f,8155400,8155448) at syscall+0x26e
Xint0x80_syscall() at Xint0x80_syscall+0x1d
--- syscall (190, FreeBSD ELF32, lstat), eip = 0x280c4e8f, esp = 0xbfbff64c, ebp = 0xbfbff6e8 ---
db>

I tried to get a dump but it failed:

db> call doadump
Dumping 510 MB
ata0: resetting devices ..
lock order reversal
 1st 0xc413a798 PCPU FFS2 dinod (UMA cpu) _at_ /a/asami/portbuild/i386/src-client/sys/vm/uma_core.c:1693
 2nd 0xc413a6e4 FFS2 dinode (UMA zone) _at_ /a/asami/portbuild/i386/src-client/sys/vm/uma_core.c:1711
 3rd 0xc14dc0d8 PCPU 512 (UMA cpu) _at_ /a/asami/portbuild/i386/src-client/sys/vm/uma_core.c:1343
S

Kris