# Re: \[RFC, PATCHv2 29/29\] mm, x86: introduce RLIMIT\_VADDR

- From: Arnd Bergmann \<arnd@arndb.de\>
- Date: 2017-01-04 13:58:26 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2017/01/4904234
- Thread: https://ratatoskr.run/linux-arm-kernel/2017/01/4902386/t.md

```text
On Tuesday, January 3, 2017 2:09:16 PM CET Andy Lutomirski wrote:
> >
> >> When
> >> ADDR_LIMIT_EXPLICIT is in effect, prctl can set a 64-bit numeric
> >> limit.  If ADDR_LIMIT_EXPLICIT is cleared, the prctl value stops being
> >> settable and reading it via prctl returns whatever is implied by the
> >> other personality bits.
> >
> > I don't see anything wrong with it, but I'm a bit confused now
> > what this would be good for, compared to using just prctl.
> >
> > Is this about setuid clearing the personality but not the prctl,
> > or something else?
> 
> It's to avid ambiguity as to what happens if you set ADDR_LIMIT_32BIT
> and use the prctl.  ISTM it would be nice for the semantics to be
> fully defined in all cases.
> 

Ok, got it.

	Arnd
```