zfs/vm panic: vm_object_page_collect_flush failed

Hi,

I've been building KDE on a new -CURRENT system with ZFS and hit a 
panic - "vm_object_page_collect_flush failed" (more info is at 
http://www.cran.org.uk/~brucec/freebsd/zfs_vm_panic.txt).

#9  0xffffffff802a6190 in panic (fmt=Variable "fmt" is not available.
)
    at /usr/src/head/sys/kern/kern_shutdown.c:574
#10 0xffffffff8043744e in vm_object_page_clean (object=Variable "object" is not available.
)
    at /usr/src/head/sys/vm/vm_object.c:823
#11 0xffffffff804376f6 in vm_object_terminate (object=0xffffff011a96d5e8)
    at /usr/src/head/sys/vm/vm_object.c:691
#12 0xffffffff804446d8 in vnode_destroy_vobject (vp=0xffffff00bd2acb40)
    at /usr/src/head/sys/vm/vnode_pager.c:167
#13 0xffffffff80a56252 in zfs_freebsd_reclaim (ap=Variable "ap" is not available.
)
    at /usr/src/head/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:4836
#14 0xffffffff803396e5 in vgonel (vp=0xffffff00bd2acb40) at vnode_if.h:830
#15 0xffffffff80339a4c in vrecycle (vp=0xffffff00bd2acb40, td=Variable "td" is not available.
)
    at /usr/src/head/sys/kern/vfs_subr.c:2517
#16 0xffffffff80a3149a in zfs_zinactive (zp=0xffffff0096d06dc0)
    at /usr/src/head/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c:1066
#17 0xffffffff80a55c96 in zfs_inactive (vp=0xffffff00bd2acb40, cr=Variable "cr" is not available.
)
    at /usr/src/head/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:4059
#18 0xffffffff80a55e3a in zfs_freebsd_inactive (ap=Variable "ap" is not available.
)
    at /usr/src/head/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:4792
#19 0xffffffff80338e92 in vinactive (vp=0xffffff00bd2acb40,
    td=0xffffff019871b450) at vnode_if.h:807
#20 0xffffffff8033c961 in vputx (vp=0xffffff00bd2acb40, func=1)
    at /usr/src/head/sys/kern/vfs_subr.c:2238
#21 0xffffffff80438dd7 in vm_object_deallocate (object=0xffffff011a96d5e8)
    at /usr/src/head/sys/vm/vm_object.c:447
#22 0xffffffff8042f68c in vm_map_entry_deallocate (entry=0xffffff00bd6054b0,
    system_map=0) at /usr/src/head/sys/vm/vm_map.c:2622
#23 0xffffffff8042f6c2 in vm_map_process_deferred ()
    at /usr/src/head/sys/vm/vm_map.c:466
#24 0xffffffff80430d2f in vm_map_remove (map=0xffffff0093adac40, start=Variable "start" is not available.
)
    at /usr/src/head/sys/vm/vm_map.c:2793
#25 0xffffffff80434057 in vmspace_exit (td=0xffffff019871b450)
    at /usr/src/head/sys/vm/vm_map.c:333
#26 0xffffffff8027bea6 in exit1 (td=0xffffff019871b450, rv=0)
    at /usr/src/head/sys/kern/kern_exit.c:299
#27 0xffffffff8027c9ee in sys_exit (td=Variable "td" is not available.
)
    at /usr/src/head/sys/kern/kern_exit.c:109
#28 0xffffffff802e699a in syscallenter (td=0xffffff019871b450,
    sa=0xffffff81b832eba0) at /usr/src/head/sys/kern/subr_trap.c:318
#29 0xffffffff8046323c in syscall (frame=0xffffff81b832ec40)
    at /usr/src/head/sys/amd64/amd64/trap.c:938
#30 0xffffffff8044dd42 in Xfast_syscall ()
    at /usr/src/head/sys/amd64/amd64/exception.S:381
#31 0x00000008006e567c in ?? ()

-- 
Bruce Cran