Re: XFS causing stack overflow

[Dave Chinner <david@xxxxxxxxxxxxx>]

On Sun, Dec 11, 2011 at 01:00:36AM +0100, Andi Kleen wrote:
> > Where does the x86-64 do the interrupt stack switch?
> 
> in entry_64.S
> 
> > 
> > I know the x86 32 bit interrupt handler switches to an irq/softirq
> > context stack, but the 64 bit one doesn't appear to. Indeed,
> > arch/x86/kernel/irq_{32,64}.c are very different, and only the 32
> > bit irq handler switches to another stack to process the
> > interrupts...
> 
> x86-64 always used interrupt stacks and has used softirq stacks
> for a long time. 32bit got to it much later (the only good 
> thing left from that 4k stack "experiment")

Oh, it's hidden in the "SAVE_ARGS_IRQ" macro. 

But that happens before do_IRQ is called, so what is the do_IRQ call
chain doing on this stack given that we've already supposed to have
switched to the interrupt stack before do_IRQ is called?

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx