Panic: mutex Giant not owned at sys/nfsclient/nfs_socket.c:461

Hello

With -CURRENT from today (and also from yesterday for that matter) I
get the panic "mutex Giant not owned at
/usr/src/sys/nfsclient/nfs_socket.c:461" sometimes (probably 1/3 of
the times) when accessing a NFS mount.  The mount was /FreeBSD, and it
panics just by typing "cd /Free<tab>" in a shell.  My last good kernel
was from Jan 17.  Does this make sense to anyone or is more
information needed?

#0  doadump () at pcpu.h:159
#1  0xc04578d1 in db_fncall (dummy1=0, dummy2=0, dummy3=1999, 
    dummy4=0xe6b5a818 "À\004\200À") at /usr/src/sys/ddb/db_command.c:531
#2  0xc0457680 in db_command (last_cmdp=0xc07ffbc4, cmd_table=0x0, 
    aux_cmd_tablep=0xc07bf8e4, aux_cmd_tablep_end=0xc07bf8e8)
    at /usr/src/sys/ddb/db_command.c:349
#3  0xc0457771 in db_command_loop () at /usr/src/sys/ddb/db_command.c:455
#4  0xc0459605 in db_trap (type=3, code=0) at /usr/src/sys/ddb/db_main.c:221
#5  0xc0587ba9 in kdb_trap (type=0, code=0, tf=0xe6b5a968)
    at /usr/src/sys/kern/subr_kdb.c:421
#6  0xc074855c in trap (frame=
      {tf_fs = 24, tf_es = 16, tf_ds = -424345584, tf_edi = 256, tf_esi = 1, tf_ebp = -424302160, t                                                                               f_isp = -424302188, tf_ebx = -424302108, tf_edx = 0, tf_ecx = -1056755712, tf_eax = 18, tf_trapno =                                                                                3, tf_err = 0, tf_eip = -1067943686, tf_cs = 8, tf_eflags = 646, tf_esp = -1065785135, tf_ss = -10                                                                               65793731})
    at /usr/src/sys/i386/i386/trap.c:573
#7  0xc073441a in calltrap () at /usr/src/sys/i386/i386/exception.s:139
#8  0x00000018 in ?? ()
#9  0x00000010 in ?? ()
#10 0xe6b50010 in ?? ()
#11 0x00000100 in ?? ()
#12 0x00000001 in ?? ()
#13 0xe6b5a9b0 in ?? ()
#14 0xe6b5a994 in ?? ()
#15 0xe6b5a9e4 in ?? ()
#16 0x00000000 in ?? ()
#17 0xc1033000 in ?? ()
#18 0x00000012 in ?? ()
#19 0x00000003 in ?? ()
#20 0x00000000 in ?? ()
#21 0xc05878fa in kdb_enter (msg=0x0) at cpufunc.h:56
#22 0xc056bc2d in panic (fmt=0xc0793caf "mutex %s not owned at %s:%d")
    at /usr/src/sys/kern/kern_shutdown.c:538
#23 0xc05626dc in _mtx_assert (m=0xc0809040, what=0, 
    file=0xc07acb3d "/usr/src/sys/nfsclient/nfs_socket.c", line=461)
    at /usr/src/sys/kern/kern_mutex.c:739
#24 0xc068bef4 in nfs_send (so=0xc1ea5b28, nam=0xc1c16960, top=0xc1d4ad00, 
    rep=0xc1ed3600) at /usr/src/sys/nfsclient/nfs_socket.c:461
#25 0xc068cef2 in nfs_request (vp=0xc1ea4450, mrest=0xc1d49800, procnum=4, 
    td=0xc1f402e0, cred=0xc21c5400, mrp=0xe6b5aabc, mdp=0xe6b5aac0, 
    dposp=0xe6b5aac4) at /usr/src/sys/nfsclient/nfs_socket.c:1027
#26 0xc0691b9b in nfs3_access_otw (vp=0xc1ea4450, wmode=-424301872, 
    td=0xc1f402e0, cred=0xc21c5400) at /usr/src/sys/nfsclient/nfs_vnops.c:263
#27 0xc0692395 in nfs_getattr (ap=0xe6b5ab70)
    at /usr/src/sys/nfsclient/nfs_vnops.c:591
#28 0xc075ed46 in VOP_GETATTR_AP (a=0x0) at vnode_if.c:484
#29 0xc05dafb9 in vn_stat (vp=0xc1ea4450, sb=0xe6b5ac78, 
    active_cred=0xc21c5400, file_cred=0x0, td=0xc1f402e0) at vnode_if.h:275
#30 0xc05d4b6e in stat (td=0xc1f402e0, uap=0xe6b5ad14)
    at /usr/src/sys/kern/vfs_syscalls.c:2091
#31 0xc0748e4f in syscall (frame=
      {tf_fs = 47, tf_es = -1078001617, tf_ds = -1078001617, tf_edi = -1078012634, tf_esi = 1348428                                                                               48, tf_ebp = -1078051128, tf_isp = -424301196, tf_ebx = -1078053184, tf_edx = -1078053280, tf_ecx =                                                                                135029248, tf_eax = 188, tf_trapno = 22, tf_err = 2, tf_eip = 672504243, tf_cs = 31, tf_eflags = 6                                                                               46, tf_esp = -1078053300, tf_ss = 47}) at /usr/src/sys/i386/i386/trap.c:951
#32 0xc073446f in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s:200


-- 
Simon L. Nielsen