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

From: Alexandre Ghiti
Date: Mon Aug 26 2019 - 03:34:21 EST

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

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

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
mm: Remove mmap_legacy_base and mmap_compat_legacy_code fields from

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(-)

Hi everyone,

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.

Thanks for taking a look,