panic: spin_lock: 0xe4ad1320, indefinitive wait!

[elekktretterr at exemail.com.au]

Our dragonfly box has got a panic last night. it runs master from last week.

I wrote down some text from the panic:

mp_lock = 00000002; cpuid = 2

Trace beginning at frame  0xe42d3b88

panic(...)
panic(...)
exponential_backoff(ff010000, 1 ,3c, e4ad1320, c727dbb)
spin_lock_wr_contested(e4ad1320, 0000000)
crfree(e4ad12b0,2, e42f3cc4, c00ef73, e42f3c00)
nlookup_done(e42f3c00, e4960720, c0304fe3, 0, c0384b5c)
sys_lstat(e32f3cf0,6,0,0dd9fce18)
syscall2(e42f3d440)

Whoever can understand this, can you tell me what happened and how can
this be fixed?

Also, is there any way to automate this: when panic occurs, automatically
start a memory dump process and then automatically reboot? I've been going
to the data center way too many times recently to investigate why the box
has crashed and it would be very helpful.

Petr