Hello, 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. Cheers, -- Steve 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 -- 1.8.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>