[RFC PATCH V5 0/6] get_user_pages_fast for ARM and ARM64
steve.capper at linaro.org
Tue May 6 08:30:03 PDT 2014
This RFC series implements get_user_pages_fast and __get_user_pages_fast.
These are required for Transparent HugePages to function correctly, as
a futex on a THP tail will otherwise result in an infinite loop (due to
the core implementation of __get_user_pages_fast always returning 0).
This series may also be beneficial for direct-IO heavy workloads and
certain KVM workloads.
The main changes since RFC V4 are:
* corrected the arm64 logic so it now correctly rcu-frees page
table backing pages.
* rcu free logic relaxed for pre-ARMv7 ARM as we need an IPI to
invalidate TLBs anyway.
* rebased to 3.15-rc3 (some minor changes were needed to allow it to merge).
* dropped Catalin's mmu_gather patch as that's been merged already.
I would really appreciate any comments (especially on the validity or
otherwise of the core fast_gup implementation) and/or testers.
Steve Capper (6):
mm: Introduce a general RCU get_user_pages_fast.
arm: mm: Introduce special ptes for LPAE
arm: mm: Enable HAVE_RCU_TABLE_FREE logic
arm: mm: Enable RCU fast_gup
arm64: mm: Enable HAVE_RCU_TABLE_FREE logic
arm64: mm: Enable RCU fast_gup
arch/arm/Kconfig | 4 +
arch/arm/include/asm/pgtable-2level.h | 2 +
arch/arm/include/asm/pgtable-3level.h | 14 ++
arch/arm/include/asm/pgtable.h | 6 +-
arch/arm/include/asm/tlb.h | 38 ++++-
arch/arm/mm/flush.c | 19 +++
arch/arm64/Kconfig | 4 +
arch/arm64/include/asm/pgtable.h | 8 +-
arch/arm64/include/asm/tlb.h | 18 ++-
arch/arm64/mm/flush.c | 19 +++
mm/Kconfig | 3 +
mm/Makefile | 1 +
mm/gup.c | 297 ++++++++++++++++++++++++++++++++++
13 files changed, 424 insertions(+), 9 deletions(-)
create mode 100644 mm/gup.c
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