Re: [PATCH RESEND 0/8] Fix mmap base in bottom-up mmap

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On 26.08.19 09:34, Alexandre Ghiti wrote:
On 6/20/19 7:03 AM, Alexandre Ghiti wrote:
This series fixes the fallback of the top-down mmap: in case of
failure, a bottom-up scheme can be tried as a last resort between
the top-down mmap base and the stack, hoping for a large unused stack
limit.

Lots of architectures and even mm code start this fallback
at TASK_UNMAPPED_BASE, which is useless since the top-down scheme
already failed on the whole address space: instead, simply use
mmap_base.

Along the way, it allows to get rid of of mmap_legacy_base and
mmap_compat_legacy_base from mm_struct.

Note that arm and mips already implement this behaviour.

Alexandre Ghiti (8):
   s390: Start fallback of top-down mmap at mm->mmap_base
   sh: Start fallback of top-down mmap at mm->mmap_base
   sparc: Start fallback of top-down mmap at mm->mmap_base
   x86, hugetlbpage: Start fallback of top-down mmap at mm->mmap_base
   mm: Start fallback top-down mmap at mm->mmap_base
   parisc: Use mmap_base, not mmap_legacy_base, as low_limit for
     bottom-up mmap
   x86: Use mmap_*base, not mmap_*legacy_base, as low_limit for bottom-up
     mmap
   mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from
     mm_struct

  arch/parisc/kernel/sys_parisc.c  |  8 +++-----
  arch/s390/mm/mmap.c              |  2 +-
  arch/sh/mm/mmap.c                |  2 +-
  arch/sparc/kernel/sys_sparc_64.c |  2 +-
  arch/sparc/mm/hugetlbpage.c      |  2 +-
  arch/x86/include/asm/elf.h       |  2 +-
  arch/x86/kernel/sys_x86_64.c     |  4 ++--
  arch/x86/mm/hugetlbpage.c        |  7 ++++---
  arch/x86/mm/mmap.c               | 20 +++++++++-----------
  include/linux/mm_types.h         |  2 --
  mm/debug.c                       |  4 ++--
  mm/mmap.c                        |  2 +-
  12 files changed, 26 insertions(+), 31 deletions(-)


Any thoughts about that series ? As said before, this is just a preparatory patchset in order to
merge x86 mmap top down code with the generic version.

I just tested your patch series successfully on the parisc
architeture. You may add:

Tested-by: Helge Deller <deller@xxxxxx> # parisc

Thanks!
Helge




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