From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Capper Subject: [RFC PATCH V4 4/7] arm: mm: Enable RCU fast_gup Date: Fri, 28 Mar 2014 15:01:29 +0000 Message-ID: <1396018892-6773-5-git-send-email-steve.capper@linaro.org> References: <1396018892-6773-1-git-send-email-steve.capper@linaro.org> Return-path: Received: from mail-wg0-f46.google.com ([74.125.82.46]:47855 "EHLO mail-wg0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751760AbaC1PBr (ORCPT ); Fri, 28 Mar 2014 11:01:47 -0400 Received: by mail-wg0-f46.google.com with SMTP id b13so3705939wgh.5 for ; Fri, 28 Mar 2014 08:01:46 -0700 (PDT) In-Reply-To: <1396018892-6773-1-git-send-email-steve.capper@linaro.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, linux@arm.linux.org.uk, linux-mm@kvack.org, linux-arch@vger.kernel.org Cc: peterz@infradead.org, gary.robertson@linaro.org, anders.roxell@linaro.org, akpm@linux-foundation.org, Steve Capper Activate the RCU fast_gup for ARM. We also need to force THP splits to broadcast an IPI s.t. we block in the fast_gup page walker. As THP splits are comparatively rare, this should not lead to a noticeable performance degradation. Signed-off-by: Steve Capper --- arch/arm/Kconfig | 3 +++ arch/arm/include/asm/pgtable-3level.h | 6 ++++++ arch/arm/mm/flush.c | 19 +++++++++++++++++++ 3 files changed, 28 insertions(+) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 7d5340d..3cf589e 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1788,6 +1788,9 @@ config ARCH_SELECT_MEMORY_MODEL config HAVE_ARCH_PFN_VALID def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM +config HAVE_RCU_GUP + def_bool y + config HIGHMEM bool "High Memory Support" depends on MMU diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h index b286ba9..fdc4a4f 100644 --- a/arch/arm/include/asm/pgtable-3level.h +++ b/arch/arm/include/asm/pgtable-3level.h @@ -226,6 +226,12 @@ static inline pte_t pte_mkspecial(pte_t pte) #ifdef CONFIG_TRANSPARENT_HUGEPAGE #define pmd_trans_huge(pmd) (pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT)) #define pmd_trans_splitting(pmd) (pmd_val(pmd) & PMD_SECT_SPLITTING) + +#ifdef CONFIG_HAVE_RCU_TABLE_FREE +#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH +void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp); +#endif #endif #define PMD_BIT_FUNC(fn,op) \ diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index 3387e60..91a2b59 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -377,3 +377,22 @@ void __flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned l */ __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE); } + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#ifdef CONFIG_HAVE_RCU_TABLE_FREE +static void thp_splitting_flush_sync(void *arg) +{ +} + +void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp) +{ + pmd_t pmd = pmd_mksplitting(*pmdp); + VM_BUG_ON(address & ~PMD_MASK); + set_pmd_at(vma->vm_mm, address, pmdp, pmd); + + /* dummy IPI to serialise against fast_gup */ + smp_call_function(thp_splitting_flush_sync, NULL, 1); +} +#endif /* CONFIG_HAVE_RCU_TABLE_FREE */ +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ -- 1.8.1.4