Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits

[Kirill A. Shutemov]

On Sun, Mar 19, 2017 at 02:25:08PM +0530, Aneesh Kumar K.V wrote:
> >>> So if I have done a successful mmap which returned > 128TB what should a
> >>> following mmap(0,...) return ? Should that now search the *full* address
> >>> space or below 128TB ?
> >>
> >> No, I don't think so. And this implementation doesn't do this.
> >>
> >> It's safer this way: if an library can't handle high addresses, it's
> >> better not to switch it automagically to full address space if other part
> >> of the process requested high address.
> >>
> >
> > What is the epectation when the hint addr is below 128TB but addr + len >
> > 128TB ? Should such mmap request fail ?
> 
> Considering that we have stack at the top (around 128TB) we may not be
> able to get a free area for such a request. But I guess the idea here is
> that if hint address is below 128TB, we behave as though our TASK_SIZE
> is 128TB ? Is that correct ?

Right.

-- 
 Kirill A. Shutemov