"Bad address" with smbfs inside a jail

I have a very new FreeBSD 7 build on a server:

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$ uname -a
FreeBSD jail1.daycos.com 7.0-PRERELEASE FreeBSD 7.0-PRERELEASE #0: Sat Jan 19 11:16:27 CST 2008     root_at_jail1.daycos.com:/usr/obj/usr/src/sys/JAIL1  i386
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Its kernel is very close to GENERIC (and I've tried GENERIC with
/etc/make.conf:CPUTYPE unset just to rule it out):

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$ cat /usr/src/sys/i386/conf/JAIL1
include                 GENERIC
ident                   JAIL1
options                 PMAP_SHPGPERPROC=301

nooption                SCHED_4BSD
option                  SCHED_ULE

# Don't let Mike accidentally reboot the server
option                  SC_DISABLE_REBOOT       # disable reboot key sequence
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I have the same smbfs share mounted in two different places on the system:
once inside the "main" system and once inside a jail.  I'm having a problem
with the jailed version when copying new files:

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$ cp /mnt/tiffsrv/vdrive/Scanned/2008/01/20/2008012014450000.tif /tmp/foo
cp: /tmp/foo: Bad address
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This only affects new files; that is, ones that have been created since
the filesystem was mounted.  If I unmount/remount the filesystem, that copy
succeeds:

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$ cp /mnt/tiffsrv/vdrive/Scanned/2008/01/20/2008012014450000.tif /tmp/foo
$
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The fstab entries for those mounts are identical:

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$ grep tiffsrv /etc/fstab
//web2_at_tiffsrv/vdrive /mnt/tiffsrv/vdrive smbfs rw,noexec 0 0
$ grep tiffsrv /etc/fstab.web2
//web2_at_tiffsrv/vdrive /var/jail/web2/mnt/tiffsrv/vdrive smbfs rw,noexec 0 0
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Again, those errors *never* happen inside the host OS - just inside that
jail.  Any suggestions?
-- 
Kirk Strauser