kernel page fault with nfs

Hi 


For some days now I've had problems with my current (last test with r273178M).

Sometimes when accessing a nfs-share there is a pagefault:

#######################################################
Fatal trap 12: page fault while in kernel mode
cpuid = 7; apic id = 07
fault virtual address   = 0xfffffe07cfe60400
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff80d4d4b6
stack pointer           = 0x28:0xfffffe086088b380
frame pointer           = 0x28:0xfffffe086088b3f0
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 43868 (mplayer)


#0  0xffffffff80926d29 in shutdown_nice (howto=1) at 
/usr/src/sys/kern/kern_shutdown.c:207
#1  0xffffffff80926a2d in kern_reboot (howto=260) at 
/usr/src/sys/kern/kern_shutdown.c:444
#2  0xffffffff80926f80 in panic (fmt=0x104 <Address 0x104 out of bounds>) at 
/usr/src/sys/kern/kern_shutdown.c:698
#3  0xffffffff8035f147 in panic_cmd_del (arg=0x0) at 
/usr/src/sys/ddb/db_command.c:244
#4  0xffffffff8035ed5d in db_command (cmd_table=0x0) at 
/usr/src/sys/ddb/db_command.c:439
#5  0xffffffff8035ead4 in db_command_loop () at /usr/src/sys/ddb/db_command.c:488
#6  0xffffffff803615e0 in db_trap (type=<value optimized out>, code=0) at 
/usr/src/sys/ddb/db_main.c:247
#7  0xffffffff80966db1 in kdb_trap (type=12, code=0, tf=0xfffffe086088b2d0) at 
/usr/src/sys/kern/subr_kdb.c:626
#8  0xffffffff80d4f92c in trap_fatal (frame=0xfffffe086088b2d0, eva=<value optimized 
out>) at /usr/src/sys/amd64/amd64/trap.c:835
#9  0xffffffff80d4fcbc in trap_pfault (frame=0xfffffe086088b2d0, usermode=0) at 
atomic.h:161
#10 0xffffffff80d4f2de in trap (frame=0xfffffe086088b2d0) at 
/usr/src/sys/amd64/amd64/trap.c:594
#11 0xffffffff80d33822 in Xtss () at /usr/src/sys/amd64/amd64/exception.S:154
#12 0xffffffff80d4d4b6 in stack_save_td (st=<value optimized out>, td=<value 
optimized out>) at /usr/src/sys/amd64/amd64/stack_machdep.c:74
#13 0xffffffff809f30b2 in foffset_unlock (fp=<value optimized out>, val=<value 
optimized out>, flags=<value optimized out>) at 
/usr/src/sys/kern/vfs_vnops.c:700
#14 0xffffffff8082faad in ncl_bioread (vp=0xfffff80201dd7490, uio=0xfffffe086088b7d8, 
ioflag=<value optimized out>, cred=0xfffff8015816a600) at 
/usr/src/sys/fs/nfsclient/nfs_clbio.c:511
#15 0xffffffff80e64381 in VOP_MARKATIME_APV (vop=<value optimized out>, 
a=0xfffffe086088b650) at vnode_if.c:856
#16 0xffffffff809f4dd5 in vn_read (fp=0xfffff80272490cd0, uio=0xfffffe086088b7d8, 
active_cred=0xfffff8015816a600, flags=128, td=0xfffff80000000000) at vnode_if.h:859
#17 0xffffffff809f5502 in get_advice (fp=0xfffffe086088b730, uio=0x400) at 
/usr/src/sys/kern/vfs_vnops.c:729
#18 0xffffffff809f2b80 in vn_io_fault1 () at /usr/src/sys/kern/vfs_vnops.c:1058
#19 0xffffffff809f0d3b in vn_io_fault (fp=0xfffff80272490cd0, uio=0xfffffe086088b970, 
active_cred=0x400, flags=128, td=0xfffff80000000000) at 
/usr/src/sys/kern/vfs_vnops.c:128
#20 0xffffffff80981d95 in freebsd6_pread (td=0xfffff802d93204a8, 
uap=0xfffff9fb094c00a8) at /usr/src/sys/kern/sys_generic.c:217
#21 0xffffffff80981ab8 in sys_cap_fcntls_get (td=<value optimized out>, uap=0x800) 
at /usr/src/sys/kern/sys_capability.c:576
#22 0xffffffff80981a43 in sys_cap_fcntls_get (td=<value optimized out>, uap=0x0) 
at sx.h:183
#23 0xffffffff80d503cb in amd64_syscall (td=0x45e400, traced=0) at 
subr_syscall.c:87
#24 0xffffffff80d33b0b in Xprot () at /usr/src/sys/amd64/amd64/exception.S:324
#25 0x0000000806a7fe6a in ?? ()
##################################################


Any hints would be appreciated. 
Please let me know if further information is required.


Thanks in advance, 
Tobias