From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f178.google.com (mail-wi0-f178.google.com [209.85.212.178]) by kanga.kvack.org (Postfix) with ESMTP id 84AC76B0035 for ; Thu, 21 Aug 2014 11:43:43 -0400 (EDT) Received: by mail-wi0-f178.google.com with SMTP id hi2so8671113wib.11 for ; Thu, 21 Aug 2014 08:43:42 -0700 (PDT) Received: from mail-wg0-f43.google.com (mail-wg0-f43.google.com [74.125.82.43]) by mx.google.com with ESMTPS id e13si9891880wik.12.2014.08.21.08.43.41 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 21 Aug 2014 08:43:41 -0700 (PDT) Received: by mail-wg0-f43.google.com with SMTP id l18so9242433wgh.2 for ; Thu, 21 Aug 2014 08:43:41 -0700 (PDT) From: Steve Capper Subject: [PATH V2 0/6] RCU get_user_pages_fast and __get_user_pages_fast Date: Thu, 21 Aug 2014 16:43:26 +0100 Message-Id: <1408635812-31584-1-git-send-email-steve.capper@linaro.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, linux@arm.linux.org.uk, linux-arch@vger.kernel.org, linux-mm@kvack.org Cc: will.deacon@arm.com, gary.robertson@linaro.org, christoffer.dall@linaro.org, peterz@infradead.org, anders.roxell@linaro.org, akpm@linux-foundation.org, dann.frazier@canonical.com, mark.rutland@arm.com, mgorman@suse.de, Steve Capper Hello, This series implements general forms of get_user_pages_fast and __get_user_pages_fast and activates them for arm and arm64. 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). Unfortunately, a futex on THP tail can be quite common for certain workloads; thus THP is unreliable without a __get_user_pages_fast implementation. This series may also be beneficial for direct-IO heavy workloads and certain KVM workloads. Changes since PATCH V1 are: * Rebase to 3.17-rc1 * Switched to kick_all_cpus_sync as suggested by Mark Rutland. The main changes since RFC V5 are: * Rebased against 3.16-rc1. * pmd_present no longer tested for by gup_huge_pmd and gup_huge_pud, because the entry must be present for these leaf functions to be called. * Rather than assume puds can be re-cast as pmds, a separate function pud_write is instead used by the core gup. * ARM activation logic changed, now it will only activate RCU_TABLE_FREE and RCU_GUP when running with LPAE. 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. This series has been tested with LTP mm tests and some custom futex tests that exacerbate the futex on THP tail case; on both an Arndale board and a Juno board. Also debug counters were temporarily employed to ensure that the RCU_TABLE_FREE logic was behaving as expected. I would really appreciate any comments (especially on the validity or otherwise of the core fast_gup implementation) and 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 | 5 + arch/arm/include/asm/pgtable-2level.h | 2 + arch/arm/include/asm/pgtable-3level.h | 15 ++ arch/arm/include/asm/pgtable.h | 6 +- arch/arm/include/asm/tlb.h | 38 ++++- arch/arm/mm/flush.c | 15 ++ arch/arm64/Kconfig | 4 + arch/arm64/include/asm/pgtable.h | 11 +- arch/arm64/include/asm/tlb.h | 20 ++- arch/arm64/mm/flush.c | 15 ++ mm/Kconfig | 3 + mm/gup.c | 278 ++++++++++++++++++++++++++++++++++ 12 files changed, 402 insertions(+), 10 deletions(-) -- 1.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org