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

From	"Kirill A. Shutemov" <kirill@shutemov.name>
Newsgroups	linux.kernel
Subject	Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits
Date	2017-03-24 10:10 +0100
Message-ID	<totom-7Is-21@gated-at.bofh.it> (permalink)
References	(1 earlier) <tkrbr-4j8-7@gated-at.bofh.it> <tm6Pg-3DI-7@gated-at.bofh.it> <tmq1z-12n-9@gated-at.bofh.it> <tmEnT-2TE-1@gated-at.bofh.it> <tmIKS-638-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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

Thread

Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-03-17 21:40 +0100
  Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above  47-bits "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-03-18 18:10 +0100
    Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-03-19 09:30 +0100
      Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-03-19 14:10 +0100
        Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above  47-bits "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-03-24 10:10 +0100
      Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits Michael Ellerman <mpe@ellerman.id.au> - 2017-03-20 10:20 +0100
      Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above 47-bits hpa@zytor.com - 2017-03-20 19:10 +0100
        Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above  47-bits Matthew Wilcox <willy@infradead.org> - 2017-03-20 20:40 +0100
        Re: [PATCH 26/26] x86/mm: allow to have userspace mappings above  47-bits "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-03-24 10:10 +0100

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