This series is a follow up to the fixes:
"[PATCH v1 0/2] mm/hugetlb: fix hugetlb vs. core-mm PT locking"
When working on the fixes, I wondered why 8xx is fine (-> never uses split
PT locks) and how PT locking even works properly with PMD page table
sharing (-> always requires split PMD PT locks).
Let's improve the split PT lock detection, make hugetlb properly depend
on it and make 8xx bail out if it would ever get enabled by accident.
As an alternative to patch #3 we could extend the Kconfig SPLIT_PTE_PTLOCKS
option from patch #2 -- but enforcing it closer to the code that actually
implements it feels a bit nicer for documentation purposes, and there
is no need to actually disable it because it should always be disabled
(!SMP).
Did a bunch of cross-compilations to make sure that split PTE/PMD
PT locks are still getting used where we would expect them.
[1] https://lkml.kernel.org/r/[email protected]
Cc: Andrew Morton <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Russell King <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: "Naveen N. Rao" <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Christian Brauner <[email protected]>
David Hildenbrand (3):
mm: turn USE_SPLIT_PTE_PTLOCKS / USE_SPLIT_PTE_PTLOCKS into Kconfig
options
mm/hugetlb: enforce that PMD PT sharing has split PMD PT locks
powerpc/8xx: document and enforce that split PT locks are not used
arch/arm/mm/fault-armv.c | 6 +++---
arch/powerpc/mm/pgtable.c | 6 ++++++
arch/x86/xen/mmu_pv.c | 7 ++++---
fs/Kconfig | 4 ++++
include/linux/hugetlb.h | 5 ++---
include/linux/mm.h | 8 ++++----
include/linux/mm_types.h | 2 +-
include/linux/mm_types_task.h | 3 ---
kernel/fork.c | 4 ++--
mm/Kconfig | 18 +++++++++++-------
mm/hugetlb.c | 8 ++++----
mm/memory.c | 2 +-
12 files changed, 42 insertions(+), 31 deletions(-)
--
2.45.2
