lkml.org 
[lkml]   [2005]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: About 4k kernel stack size....
On Tue, Dec 20, 2005 at 09:37:28AM -0500, Mike Snitzer wrote:
> 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)?

Besides the fact that I still don't think it's requred, Matt's
suggestion would work only randomly for functions using more than 1 kB
stack.

But discussing hypothetical patches is silly - code talks.

If someone sends a patch implementing Mark's suggestion and it gets
measured that this patch doesn't impose a performance penalty we'd
have a basis for a real discussion.

> Mike

cu
Adrian

--

"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-12-20 16:03    [W:1.471 / U:0.620 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site