panic: uma_small_alloc: free page still has mappings!

Panic on SMP sparc machine running up-to-date 7.0.

login: Aug 19 13:28:57 e4500 kernel: pid 32590 (ld), uid 0 inumber 25816 on : filesystem full
Aug 19 13:29:00 e4500 kernel: pid 33164 (cat), uid 0 inumber 48589 on : filesystem full
KpDDi: stakk balkrraee:
fassssertevotickckes )tat agre_Do:us_ cc ed+6x:4c
                                                 vo
                                                   :lock_pto[thread pid 86114 tid 101592 ]
Stopped at      kdb_enter+0x3c: ta              %xcc, 1
db> wh
Tracing pid 86114 tid 101592 td 0xfffff8011e0b6980
panic() at panic+0x164
uma_small_alloc() at uma_small_alloc+0x9c
slab_zalloc() at slab_zalloc+0x98
uma_zone_slab() at uma_zone_slab+0x12c
uma_zalloc_bucket() at uma_zalloc_bucket+0x16c
uma_zalloc_arg() at uma_zalloc_arg+0x330
malloc() at malloc+0x114
allocbuf() at allocbuf+0x208
getblk() at getblk+0x5a8
ffs_balloc_ufs2() at ffs_balloc_ufs2+0xa30
ufs_mkdir() at ufs_mkdir+0x55c
VOP_MKDIR_APV() at VOP_MKDIR_APV+0xcc
kern_mkdir() at kern_mkdir+0x2f0
mkdir() at mkdir+0x10
syscall() at syscall+0x2dc
-- syscall (136, FreeBSD ELF64, mkdir) %o7=0x105b90 --
userland() at 0x40527d08
user trace: trap %o7=0x105b90
pc 0x40527d08, sp 0x7fdffffd5d1
pc 0x105c6c, sp 0x7fdffffd711
done

The panicstr is:

panic: uma_small_alloc: free page still has mappings!

Kris