Re: [CHECKER] large stack variables (>=1K) in 2.4.4 and 2.4.4-ac8

Andi Kleen
2001-05-25T08:40:39Z

On Fri, May 25, 2001 at 06:31:20PM +1000, Keith Owens wrote:
> That is exactly what I said above, a separate fault task with its own
> stack for every cpu. But there is no point in doing this to detect a
> hardware stack overflow when the overflow has already corrupted the
> struct task which is at the bottom of the stack segment.

You can at least get a backtrace, which is useful enough.

>
> To get any benefit from hardware detection of kernel stack overflow you
> must also dedicate the stack segment to hold only stack data. That
> means moving struct task to yet another page, adding an extra page per
> task. It is just too expensive, we write better code than that.

Ah this was a misunderstanding. I was just talking about plain recovery
from stack faults; not from hardware stack overflow detection. Even without
wather tight overflow detection they happen often enough and usually not
too long after a stack page overflow.

-Andi