unionfs related panic on 10.0-ALPHA4

[Olivier Cochard-Labbé]

I've just have another crash related to mount_unionfs but on sparc64
arch this time  ( 10.0-ALPHA4 #2 r255947).

Still no core dump:

panic: vm_fault: fault on nofault entry, addr: 1c05f2000
cpuid = 0
KDB: stack backtrace:
panic() at panic+0x1d4
vm_fault_hold() at vm_fault_hold+0x174
vm_fault() at vm_fault+0x88
trap_pfault() at trap_pfault+0x2e4
trap() at trap+0x308
-- fast instruction access mmu miss tar=0x1c05f2000 %o7=0x17ae23b4c --
_end() at 0x1c05f21a0
vfs_donmount() at vfs_donmount+0x1958
sys_nmount() at sys_nmount+0x78
syscall() at syscall+0x320
-- syscall (378, FreeBSD ELF64, sys_nmount) %o7=0x10141c --
userland() at 0x4047f968
user trace: trap %o7=0x10141c
pc 0x4047f968, sp 0x7fdffffcff1
pc 0x100e24, sp 0x7fdffffda01
pc 0x402058f4, sp 0x7fdffffdac1
done
KDB: enter: panic
[ thread pid 73492 tid 100396 ]
Stopped at      kdb_enter+0x80: ta              %xcc, 1

db> show thread
Thread 100396 at 0xfffff80005598920:
 proc (pid 73492): 0xfffff8000591c4b0
 name: mount_unionfs
 stack: 0xed2aa000-0xed2b1fff
 flags: 0x4  pflags: 0
 state: RUNNING (CPU 0)
 priority: 152
 container lock: sched lock 0 (0xc0c4a800)
db> show all trace

Tracing command mount_unionfs pid 73492 tid 100396 td 0xfffff80005598920
panic() at panic+0x218
vm_fault_hold() at vm_fault_hold+0x174
vm_fault() at vm_fault+0x88
trap_pfault() at trap_pfault+0x2e4
trap() at trap+0x308
-- fast instruction access mmu miss tar=0x1c05f2000 %o7=0x17ae23b4c --
_end() at 0x1c05f21a0
vfs_donmount() at vfs_donmount+0x1958
sys_nmount() at sys_nmount+0x78
syscall() at syscall+0x320
-- syscall (378, FreeBSD ELF64, sys_nmount) %o7=0x10141c --
userland() at 0x4047f968
user trace: trap %o7=0x10141c
pc 0x4047f968, sp 0x7fdffffcff1
pc 0x100e24, sp 0x7fdffffda01
pc 0x402058f4, sp 0x7fdffffdac1
done
...