[PATCH v4 0/9] Fixup page directory freeing

Aneesh Kumar K.V
2020-01-16T06:46:00Z

This is a repost of patch series from Peter with the arch specific changes except ppc64 dropped.
ppc64 changes are added here because we are redoing the patch series on top of ppc64 changes. This makes it
easy to backport these changes. Only the first 2 patches need to be backported to stable.

The thing is, on anything SMP, freeing page directories should observe the
exact same order as normal page freeing:

1) unhook page/directory
2) TLB invalidate
3) free page/directory

Without this, any concurrent page-table walk could end up with a Use-after-Free.
This is esp. trivial for anything that has software page-table walkers
(HAVE_FAST_GUP / software TLB fill) or the hardware caches partial page-walks
(ie. caches page directories).

Even on UP this might give issues since mmu_gather is preemptible these days.
An interrupt or preempted task accessing user pages might stumble into the free
page if the hardware caches page directories.

This patch series fixup ppc64 and add generic MMU_GATHER changes to support the conversion of other architectures.
I haven't added patches w.r.t other architecture because they are yet to be acked.

Changes from V3:
* Added Cc:stable for first two patches
* Explained why we have sparc related changes in patch 2

Aneesh Kumar K.V (1):
powerpc/mmu_gather: Enable RCU_TABLE_FREE even for !SMP case

Peter Zijlstra (8):
mm/mmu_gather: Invalidate TLB correctly on batch allocation failure
and flush
asm-generic/tlb: Avoid potential double flush
asm-gemeric/tlb: Remove stray function declarations
asm-generic/tlb: Add missing CONFIG symbol
asm-generic/tlb: Rename HAVE_RCU_TABLE_FREE
asm-generic/tlb: Rename HAVE_MMU_GATHER_PAGE_SIZE
asm-generic/tlb: Rename HAVE_MMU_GATHER_NO_GATHER
asm-generic/tlb: Provide MMU_GATHER_TABLE_FREE

arch/Kconfig | 13 +-
arch/arm/Kconfig | 2 +-
arch/arm/include/asm/tlb.h | 4 -
arch/arm64/Kconfig | 2 +-
arch/powerpc/Kconfig | 5 +-
arch/powerpc/include/asm/book3s/32/pgalloc.h | 8 --
arch/powerpc/include/asm/book3s/64/pgalloc.h | 2 -
arch/powerpc/include/asm/nohash/pgalloc.h | 8 --
arch/powerpc/include/asm/tlb.h | 11 ++
arch/powerpc/mm/book3s64/pgtable.c | 7 -
arch/s390/Kconfig | 4 +-
arch/sparc/Kconfig | 3 +-
arch/sparc/include/asm/tlb_64.h | 9 ++
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/tlb.h | 4 +-
include/asm-generic/tlb.h | 120 ++++++++++-------
mm/gup.c | 2 +-
mm/mmu_gather.c | 134 +++++++++++++------
18 files changed, 207 insertions(+), 133 deletions(-)

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2.24.1