Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR

From	Andy Lutomirski <luto@amacapital.net>
Newsgroups	linux.kernel
Subject	Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR
Date	2017-02-18 00:10 +0100
Message-ID	<tbZP3-2hr-13@gated-at.bofh.it> (permalink)
References	<tbRy9-5mq-3@gated-at.bofh.it> <tbRyb-5mq-61@gated-at.bofh.it> <tbX0T-q0-47@gated-at.bofh.it> <tbXkd-wK-7@gated-at.bofh.it> <tbXWV-11n-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Feb 17, 2017 at 1:01 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Fri, Feb 17, 2017 at 12:12 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>>
>> At the very least, I'd want to see
>> MAP_FIXED_BUT_DONT_BLOODY_UNMAP_ANYTHING.  I *hate* the current
>> interface.
>
> That's unrelated, but I guess w could add a MAP_NOUNMAP flag, and then
> you can use MAP_FIXED | MAP_NOUNMAP or something.
>
> But that has nothing to do with the 47-vs-56 bit issue.
>
>> How about MAP_LIMIT where the address passed in is interpreted as an
>> upper bound instead of a fixed address?
>
> Again, that's a unrelated semantic issue. Right now - if you don't
> pass in MAP_FIXED at all, the "addr" argument is used as a starting
> value for deciding where to find an unmapped area. But there is no way
> to specify the end. That would basically be what the process control
> thing would be (not per-system-call, but per-thread ).
>

What I'm trying to say is: if we're going to do the route of 48-bit
limit unless a specific mmap call requests otherwise, can we at least
have an interface that doesn't suck?

Thread

[PATCHv3 00/33] 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 30/33] x86/mm: make kernel_physical_mapping_init() support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 14/33] x86/kexec: support p4d_t "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 25/33] x86/dump_pagetables: support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 12/33] x86/mm: add support of p4d_t in vmalloc_fault() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 10/33] x86/gup: add 5-level paging support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 27/33] x86/espfix: support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 05/33] asm-generic: introduce <asm-generic/pgtable-nop4d.h> "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 15/33] x86/efi: handle p4d in EFI pagetables "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
    Re: [PATCHv3 15/33] x86/efi: handle p4d in EFI pagetables Matt Fleming <matt@codeblueprint.co.uk> - 2017-02-28 13:40 +0100
  [PATCHv3 32/33] x86: enable 5-level paging support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 26/33] x86/kasan: extend to support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
  [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
    Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-02-17 18:00 +0100
      Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Dmitry Safonov <0x7f454c46@gmail.com> - 2017-02-21 13:00 +0100
        Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-21 13:50 +0100
    Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-02-17 18:30 +0100
      Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-02-17 18:30 +0100
    Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-17 21:10 +0100
      Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-02-17 21:30 +0100
        Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-17 22:10 +0100
          Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-02-18 00:10 +0100
            Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR hpa@zytor.com - 2017-02-18 00:20 +0100
            Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Michael Pratt <mpratt@google.com> - 2017-02-21 07:20 +0100
            Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR Catalin Marinas <catalin.marinas@arm.com> - 2017-02-21 11:40 +0100
              Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-21 11:50 +0100
                Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR Catalin Marinas <catalin.marinas@arm.com> - 2017-02-21 12:00 +0100
      Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-02-17 22:10 +0100
        Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-17 22:20 +0100
          Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR hpa@zytor.com - 2017-02-17 23:00 +0100
      Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-18 10:30 +0100
        Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-20 14:20 +0100
          Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-02-21 21:50 +0100
            Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and  PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-22 14:10 +0100
  [PATCHv3 23/33] x86/paravirt: make paravirt code support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 13/33] x86/power: support p4d_t in hibernate code "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 28/33] x86/mm: add support of additional page table level during early boot "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 21/33] x86/asm: remove __VIRTUAL_MASK_SHIFT==47 assert "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 04/33] arch, mm: convert all architectures to use 5level-fixup.h "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 01/33] x86/cpufeature: Add 5-level paging detection "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 08/33] x86: basic changes into headers for 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 03/33] asm-generic: introduce __ARCH_USE_5LEVEL_HACK "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 07/33] mm: introduce __p4d_alloc() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 16/33] x86/mm/pat: handle additional page table "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 19/33] x86: convert the rest of the code to support p4d_t "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 11/33] x86/ident_map: add 5-level paging support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
  [PATCHv3 18/33] x86/xen: convert __xen_pgd_walk() and xen_cleanmfnmap() to support p4d "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100

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