stable/9 igb(4) panic, udp_append

[Gleb Smirnoff]

On Fri, Sep 07, 2012 at 12:35:53AM -0700, Sean Bruno wrote:
S> Just noted this happened today, running stable/9 ish from august 10th.
S> It looks like I got a good and valid crashdump off of this if anyone is
S> interested.
...
S> --- trap 0xc, rip = 0xffffffff80731312, rsp = 0xffffff846c8977d0, rbp =
S> 0xffffff846c897860 ---
S> udp_append() at udp_append+0x62
S> udp_input() at udp_input+0x4c8
S> ip_input() at ip_input+0xbd

I guess I know this one. The problem is a race in in_pcblookup_*() when
two threads want to acquire a pcb read-locked and third thread detaches
it. I have reported this to Robert and now waiting for reply.

-- 
Totus tuus, Glebius.