Re: [BUG] get_unmapped_area() change -> non booting machine

[Andi Kleen]

On Fri, 13 Feb 2004 03:26:04 +0000
Jamie Lokier <jamie@xxxxxxxxxxxxx> wrote:

> Linus Torvalds wrote:
> > One option is to mark the brk() VMA's as being grow-up (which they are), 
> > and make get_unmapped_area() realize that it should avoid trying to 
> > allocate just above grow-up segments or just below grow-down segments. 
> > That's still something of a special case, but at least it's not "magic" 
> > any more, now it's more of a "makes sense".
> 
> That reminds me.  What happens when grow-down stack VMAs finally bump
> into another VMA.  Is there an unmapped guard page retained to segfault
> the program, or does the program silently start overwriting the VMA it
> bumped into?

In the standard kernel it silently overwrites, but in 2.4-aa there was a patch forever
that adds a guard page.

-Andi
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