Re: About 4k kernel stack size....

[Mike Snitzer <snitzer@gmail.com>]

On 12/20/05, Adrian Bunk <bunk@stusta.de> wrote:
> On Mon, Dec 19, 2005 at 09:52:53PM -0500, Mark Lord wrote:
> >...
> > The mainline code paths are undoubtedly fine with 4K stacks.
> > It's the *error paths* that are most likely to go deeper on the stack,
> > and those are rarely exercised by anyone.  And those are the paths
> > that we *really* need to be reliable.
>
> "most likely" is a strong sentence, especially considering that the
> automatic analysis of all possible call chains can and has already
> identified several such problems (which have now been fixed many months
> ago).
>
> We might not getting 100% security against stack overflows, but that's
> not fundamentally different from the current situation with 6 kB stacks.

Given this last statement, why is it that Matt Mackall's suggestion in
the "Light-weight dynamically extended stacks" thread didn't get any
_real_ discussion from the big 4K stack advocates?  For all intents
and purposes, Matt was dismissed with the same Bunk: "Ever since
neilb's patch there are 0 bugs.. blah blah".  4K, 8K (aka "6 kB")
aside; having more stack safety in the Linux kernel is a "good thing"
no?  Aren't dynamic stacks a viable means to imposing 4K (but doing so
with real safety)?

Mike