From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757252Ab2KVWue (ORCPT ); Thu, 22 Nov 2012 17:50:34 -0500 Received: from mail-ea0-f174.google.com ([209.85.215.174]:47171 "EHLO mail-ea0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753074Ab2KVWu3 (ORCPT ); Thu, 22 Nov 2012 17:50:29 -0500 From: Ingo Molnar To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Peter Zijlstra , Paul Turner , Lee Schermerhorn , Christoph Lameter , Rik van Riel , Mel Gorman , Andrew Morton , Andrea Arcangeli , Linus Torvalds , Thomas Gleixner , Johannes Weiner , Hugh Dickins , Michel Lespinasse Subject: [PATCH 02/33] x86/mm: Only do a local tlb flush in ptep_set_access_flags() Date: Thu, 22 Nov 2012 23:49:23 +0100 Message-Id: <1353624594-1118-3-git-send-email-mingo@kernel.org> X-Mailer: git-send-email 1.7.11.7 In-Reply-To: <1353624594-1118-1-git-send-email-mingo@kernel.org> References: <1353624594-1118-1-git-send-email-mingo@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rik van Riel Because we only ever upgrade a PTE when calling ptep_set_access_flags(), it is safe to skip flushing entries on remote TLBs. The worst that can happen is a spurious page fault on other CPUs, which would flush that TLB entry. Lazily letting another CPU incur a spurious page fault occasionally is (much!) cheaper than aggressively flushing everybody else's TLB. Signed-off-by: Rik van Riel Acked-by: Linus Torvalds Acked-by: Peter Zijlstra Cc: Andrew Morton Cc: Michel Lespinasse Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Mel Gorman Cc: Thomas Gleixner Cc: Hugh Dickins Signed-off-by: Ingo Molnar --- arch/x86/mm/pgtable.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 8573b83..be3bb46 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -301,6 +301,13 @@ void pgd_free(struct mm_struct *mm, pgd_t *pgd) free_page((unsigned long)pgd); } +/* + * Used to set accessed or dirty bits in the page table entries + * on other architectures. On x86, the accessed and dirty bits + * are tracked by hardware. However, do_wp_page calls this function + * to also make the pte writeable at the same time the dirty bit is + * set. In that case we do actually need to write the PTE. + */ int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address, pte_t *ptep, pte_t entry, int dirty) @@ -310,7 +317,7 @@ int ptep_set_access_flags(struct vm_area_struct *vma, if (changed && dirty) { *ptep = entry; pte_update_defer(vma->vm_mm, address, ptep); - flush_tlb_page(vma, address); + __flush_tlb_one(address); } return changed; -- 1.7.11.7