panic: lockmgr: locking against myself

I've been getting quite a few of these lately:

kgdb: kvm_nlist(_stopped_cpus):
kgdb: kvm_nlist(_stoppcbs):
[GDB will not be able to debug user-mode threads: /usr/lib/libthread_db.so: Undefined symbol "ps_pglobal_lookup"]
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This GDB was configured as "i386-marcel-freebsd".
Ready to go.  Enter 'tr' to connect to the remote target
with /dev/cuad0, 'tr /dev/cuad1' to connect to a different port
or 'trf portno' to connect to the remote target with the firewire
interface.  portno defaults to 5556.

Type 'getsyms' after connection to load kld symbols.

If you're debugging a local system, you can use 'kldsyms' instead
to load the kld symbols.  That's a less obnoxious interface.

Unread portion of the kernel message buffer:
panic: lockmgr: locking against myself
Uptime: 42m41s
Physical memory: 2039 MB
Dumping 327 MB: 312 296 280 264 248 232 216 200 184 168 152 136 120 104 88 72 56 40 24 8

#0  doadump () at pcpu.h:172
172     pcpu.h: No such file or directory.
        in pcpu.h
(kgdb) getsyms
During symbol reading, Incomplete CFI data; unspecified registers at 0xc05301f7.
Id Refs Address    Size     Name
 1   13 0xc0400000 3f7698   kernel
 2    1 0xc07f8000 68b0     geom_label.ko
 3    1 0xc07ff000 1728c    geom_mirror.ko
 4    1 0xc0817000 7d1c     geom_stripe.ko
 5    1 0xc081f000 bdd8     if_sk.ko
 6    1 0xc513d000 a0000    zfs.ko
 7    1 0xc8015000 3000     pflog.ko
 8    1 0xc8018000 35000    pf.ko
 9    1 0xc8682000 36000    nfsclient.ko
10    1 0xc86ca000 1f000    nfsserver.ko
Select the list above with the mouse, paste into the screen
and then press ^D.  Yes, this is annoying.
 1   13 0xc0400000 3f7698   kernel
 2    1 0xc07f8000 68b0     geom_label.ko
 3    1 0xc07ff000 1728c    geom_mirror.ko
 4    1 0xc0817000 7d1c     geom_stripe.ko
 5    1 0xc081f000 bdd8     if_sk.ko
 6    1 0xc513d000 a0000    zfs.ko
 7    1 0xc8015000 3000     pflog.ko
 8    1 0xc8018000 35000    pf.ko
 9    1 0xc8682000 36000    nfsclient.ko
10    1 0xc86ca000 1f000    nfsserver.ko
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/sk/if_sk.ko.debug" at
        .text_addr = 0xc08216c4
        .data_addr = 0xc0829000
        .bss_addr = 0xc082936c
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/pflog/pflog.ko.debug" at
        .text_addr = 0xc8015bec
        .data_addr = 0xc8017360
        .bss_addr = 0xc8017518
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/geom/geom_mirror/geom_mirror.ko.debug" at
        .text_addr = 0xc0805e70
        .data_addr = 0xc0814000
        .bss_addr = 0xc08143c4
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/geom/geom_label/geom_label.ko.debug" at
        .text_addr = 0xc07f9d0c
        .data_addr = 0xc07fd940
        .bss_addr = 0xc07fdb10
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/geom/geom_stripe/geom_stripe.ko.debug" at
        .text_addr = 0xc0819194
        .data_addr = 0xc081d6a0
        .bss_addr = 0xc081d9b8
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/nfsserver/nfsserver.ko.debug" at
        .text_addr = 0xc86cf048
        .data_addr = 0xc86e3000
        .bss_addr = 0xc86e3600
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/zfs/zfs.ko.debug" at
        .text_addr = 0xc5150b10
        .data_addr = 0xc51cf000
        .bss_addr = 0xc51d1680
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/nfsclient/nfsclient.ko.debug" at
        .text_addr = 0xc868cc20
        .data_addr = 0xc86b5660
        .bss_addr = 0xc86b6cc0
add symbol table from file "/usr/obj/usr/src/sys/dwp/modules/usr/src/sys/modules/pf/pf.ko.debug" at
        .text_addr = 0xc801f31c
        .data_addr = 0xc8049000
        .bss_addr = 0xc80491e0
(kgdb) where
#0  doadump () at pcpu.h:172
During symbol reading, Incomplete CFI data; unspecified registers at 0xc05301f7.
#1  0xc053096e in boot (howto=0x104) at /usr/src/sys/kern/kern_shutdown.c:409
#2  0xc053043b in panic (fmt=0x0) at /usr/src/sys/kern/kern_shutdown.c:563
#3  0xc05225fb in _lockmgr (lkp=0xcf55e278, flags=0x3002, interlkp=0xcf55e278, td=0xc5235870,
    file=0xc86e248a "/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c", line=0xac9)
    at /usr/src/sys/kern/kern_lock.c:448
#4  0xc0594392 in vop_stdlock (ap=0x0) at /usr/src/sys/kern/vfs_default.c:266
#5  0xc06a70df in _VOP_LOCK_APV (vop=0x0, a=0xf4643860) at vnode_if.c:1617
#6  0xc05abb06 in _vn_lock (vp=0xcf55e220, flags=0x1002, td=0xc5235870,
    file=0xc86e248a "/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c", line=0xac9)
    at vnode_if.h:850
#7  0xc86d33df in nfsrv_symlink (nfsd=0xcfd7fb00, slp=0x0, td=0xc5235870, mrq=0xf4643bfc)
    at /usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c:2761
#8  0xc86e10a8 in nfssvc (td=0xc5235870, uap=0xca2f6b80)
    at /usr/src/sys/modules/nfsserver/../../nfsserver/nfs_syscalls.c:477
#9  0xc069437f in syscall (frame=0xf4643d38) at /usr/src/sys/i386/i386/trap.c:1008
#10 0xc067f1c0 in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s:196
#11 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)

DES
-- 
Dag-Erling Smørgrav - des_at_des.no