Re: [PATCH 0/2] mm: introduce MAP_FIXED_SAFE

From: Michal Hocko
Date: Wed Dec 06 2017 - 04:08:20 EST


On Wed 06-12-17 08:33:37, Rasmus Villemoes wrote:
> On 2017-12-06 05:50, Michael Ellerman wrote:
> > Michal Hocko <mhocko@xxxxxxxxxx> writes:
> >
> >> On Wed 29-11-17 14:25:36, Kees Cook wrote:
> >> It is safe in a sense it doesn't perform any address space dangerous
> >> operations. mmap is _inherently_ about the address space so the context
> >> should be kind of clear.
> >
> > So now you have to define what "dangerous" means.
> >
> >>> MAP_FIXED_UNIQUE
> >>> MAP_FIXED_ONCE
> >>> MAP_FIXED_FRESH
> >>
> >> Well, I can open a poll for the best name, but none of those you are
> >> proposing sound much better to me. Yeah, naming sucks...
>
> I also don't like the _SAFE name - MAP_FIXED in itself isn't unsafe [1],
> but I do agree that having a way to avoid clobbering (parts of) an
> existing mapping is quite useful. Since we're bikeshedding names, how
> about MAP_FIXED_EXCL, in analogy with the O_ flag.

I really give up on the name discussion. I will take whatever the
majority comes up with. I just do not want this (useful) funtionality
get bikeched to death.
--
Michal Hocko
SUSE Labs