[PATCH] Restrict initial stack space expansion to rlimit

[KOSAKI Motohiro]

> On 02/09/2010 10:51 PM, Michael Neuling wrote:
> >>> I'd still like someone with a CONFIG_STACK_GROWSUP arch to test/ACK it
> >>> as well.
> >>
> >> There's only one CONFIG_GROWSUP arch - parisc.
> >> Could someone please test it on parisc?
> 
> I did.
> 
> > How about doing:
> >    'ulimit -s 15; ls'
> > before and after the patch is applied.  Before it's applied, 'ls' should
> > be killed.  After the patch is applied, 'ls' should no longer be killed.
> >
> > I'm suggesting a stack limit of 15KB since it's small enough to trigger
> > 20*PAGE_SIZE.  Also 15KB not a multiple of PAGE_SIZE, which is a trickier
> > case to handle correctly with this code.
> >
> > 4K pages on parisc should be fine to test with.
> 
> Mikey, thanks for the suggested test plan.
> 
> I'm not sure if your patch does it correct for parisc/stack-grows-up-case.
> 
> I tested your patch on  a 4k pages kernel:
> root at c3000:~# uname -a
> Linux c3000 2.6.33-rc7-32bit #221 Tue Feb 9 23:17:06 CET 2010 parisc GNU/Linux
> 
> Without your patch:
> root at c3000:~# ulimit -s 15; ls
> Killed
> -> correct.
> 
> With your patch:
> root at c3000:~# ulimit -s 15; ls
> Killed
> _or_:
> root at c3000:~# ulimit -s 15; ls
> Segmentation fault
> -> ??
> 
> Any idea?

My x86_64 box also makes segmentation fault. I think "ulimit -s 15" is too small stack for ls.
"ulimit -s 27; ls "  wroks perfectly fine.