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

[Michael Ellerman]

"Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> writes:
> "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> writes:
>> On Fri, Mar 17, 2017 at 11:23:54PM +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 ?

Yeah I think that makes sense, it retains the existing behaviour unless
the hint itself is >= 128TB.

cheers