Linus Torvalds wrote:
> 
> On Sat, 23 Aug 2008, Linus Torvalds wrote:
>> This one makes no sense. It's triggering a BUG_ON(in_interrupt()), but 
>> then the call chain shows that there is no interrupt going on.
> 
> Ahh, later in that thread there's another totally unrelated oops in 
> debug_mutex_add_waiter().
> 
> I'd guess that it is really wild pointer corrupting memory, quite possibly 
> due to a double free or something like that. Alan - it would be good to 
> run with DEBUG_PAGE_ALLOC and SLUB debugging etc if you don't already do 
> that?

With /just/ DEBUG_PAGE_ALLOC defined, I have seen two general panic types:

o  A new double fault w/ SMP_DEBUG_PAGEALLOC problem (prob4.txt)

o  The NULL pointer dereference @ 0x858 (prob4a.txt)

Enabling SLUB debugging to see what that shows

Alan