[0/8] Fix mmap base in bottom-up mmap

Message

Alexandre Ghiti June 19, 2019, 5:08 a.m. UTC

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(-)