Re: [PATCH 3/5] stack overflow safe kdump (2.6.16-rc1-i386) - fault

[Andi Kleen]

On Wednesday 25 January 2006 08:15, Andrew Morton wrote:
> Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxxxxxx> wrote:
> > When we have a bloated stack it is likely that it ends up making an
> > invalid memory access that in turn causes a page fault. Take this case
> > into account in the page fault code.
> >
> > +	if (!virt_addr_valid(tsk)) {
>
> Is virt_addr_valid() a sufficiently strong test here?  One could probe the
> address to see if it generates a fault, like the __get_user() in
> kmem_cache_create().

Recursive page faults are always risky because if things go bad they
can lead to unbounded recursion.   I think the scheduler knows anyways
which process currently executes on a CPU so it might be better to get
the information from there.

-Andi

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