[PATCH mm-stable v2 0/3] mm/ksm: improve PR_SET_MEMORY_MERGE=0 handling and cleanup disabling KSM

[David Hildenbrand]

This is a follow-up to [1]:
	[PATCH v9 0/3] mm: process/cgroup ksm support

which is now in mm-stable. Ideally we'd get at least patch #1 into the
same kernel release as [1], so the semantics of setting
PR_SET_MEMORY_MERGE=0 are unchanged between kernel versions.

(1) Make PR_SET_MEMORY_MERGE=0 unmerge pages like setting MADV_UNMERGEABLE
does, (2) add a selftest for it and (3) factor out disabling of KSM from
s390/gmap code.

v1 -> v2:
- "mm/ksm: unmerge and clear VM_MERGEABLE when setting
   PR_SET_MEMORY_MERGE=0"
 -> Cleanup one if/else
 -> Add doc for ksm_disable_merge_any()
- Added ACKs

[1] https://lkml.kernel.org/r/20230418051342.1919757-1-shr@xxxxxxxxxxxx

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Stefan Roesch <shr@xxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Janosch Frank <frankja@xxxxxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>

David Hildenbrand (3):
  mm/ksm: unmerge and clear VM_MERGEABLE when setting
    PR_SET_MEMORY_MERGE=0
  selftests/ksm: ksm_functional_tests: add prctl unmerge test
  mm/ksm: move disabling KSM from s390/gmap code to KSM code

 arch/s390/mm/gmap.c                           | 20 +-----
 include/linux/ksm.h                           |  7 ++
 kernel/sys.c                                  | 12 +---
 mm/ksm.c                                      | 70 +++++++++++++++++++
 .../selftests/mm/ksm_functional_tests.c       | 46 ++++++++++--
 5 files changed, 121 insertions(+), 34 deletions(-)

-- 
2.40.0