Re: heap-stack-gap for 2.6

[Andrea Arcangeli <andrea@novell.com>]

On Wed, Sep 29, 2004 at 03:24:46PM +0100, Alan Cox wrote:
> As the man page says
> 
> "Use of this option is discouraged."

and as a matter of fact the vast majority of mmaps executed by databases
with vlm are using MAP_FIXED ;)

I'm not saying databases themself are going to break with topdown, I'm just saying
there are applications out there making heavy use of MAP_FIXED, no
matter if the above manpage says it's discouraged. depending on
applications not to use it, isn't reliable and it's prone to break
randomly at runtime with topdown, this is my _only_ point, and it's a
tangible fact as far as I can tell (not a purerly theoretical issue like
the set_pte not being exceuted in asm).

If you want to make your kernel really safe, then disable MAP_FIXED and
return -EINVAL, then I agree it will be safe.