From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4954AC169C4 for ; Thu, 31 Jan 2019 18:37:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26C25218AC for ; Thu, 31 Jan 2019 18:37:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727960AbfAaShV (ORCPT ); Thu, 31 Jan 2019 13:37:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34368 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727917AbfAaShT (ORCPT ); Thu, 31 Jan 2019 13:37:19 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8D85489AF1; Thu, 31 Jan 2019 18:37:19 +0000 (UTC) Received: from localhost.localdomain.com (unknown [10.20.6.236]) by smtp.corp.redhat.com (Postfix) with ESMTP id 87A7A18506; Thu, 31 Jan 2019 18:37:18 +0000 (UTC) From: jglisse@redhat.com To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Andrea Arcangeli , Peter Xu , Andrew Morton , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , kvm@vger.kernel.org Subject: [RFC PATCH 3/4] mm/mmu_notifier: set MMU_NOTIFIER_USE_CHANGE_PTE flag where appropriate Date: Thu, 31 Jan 2019 13:37:05 -0500 Message-Id: <20190131183706.20980-4-jglisse@redhat.com> In-Reply-To: <20190131183706.20980-1-jglisse@redhat.com> References: <20190131183706.20980-1-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Thu, 31 Jan 2019 18:37:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jérôme Glisse When notifying change for a range use MMU_NOTIFIER_USE_CHANGE_PTE flag for page table update that use set_pte_at_notify() and where the we are going either from read and write to read only with same pfn or read only to read and write with new pfn. Note that set_pte_at_notify() itself should only be use in rare cases ie we do not want to use it when we are updating a significant range of virtual addresses and thus a significant number of pte. Instead for those cases the event provided to mmu notifer invalidate_range_start() callback should be use for optimization. Signed-off-by: Jérôme Glisse Cc: Andrea Arcangeli Cc: Peter Xu Cc: Andrew Morton Cc: Paolo Bonzini Cc: Radim Krčmář Cc: kvm@vger.kernel.org --- include/linux/mmu_notifier.h | 13 +++++++++++++ mm/ksm.c | 6 ++++-- mm/memory.c | 3 ++- 3 files changed, 19 insertions(+), 3 deletions(-) diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h index d7a35975c2bd..0885bf33dc9c 100644 --- a/include/linux/mmu_notifier.h +++ b/include/linux/mmu_notifier.h @@ -43,6 +43,19 @@ enum mmu_notifier_event { }; #define MMU_NOTIFIER_EVENT_BITS order_base_2(MMU_NOTIFY_EVENT_MAX) +/* + * Set MMU_NOTIFIER_USE_CHANGE_PTE only when the page table it updated with the + * set_pte_at_notify() and when pte is updated from read and write to read only + * with same pfn or from read only to read and write with different pfn. It is + * illegal to set in any other circumstances. + * + * Note that set_pte_at_notify() should not be use outside of the above cases. + * When updating a range in batch (like write protecting a range) it is better + * to rely on invalidate_range_start() and struct mmu_notifier_range to infer + * the kind of update that is happening (as an example you can look at the + * mmu_notifier_range_update_to_read_only() function). + */ +#define MMU_NOTIFIER_USE_CHANGE_PTE (1 << MMU_NOTIFIER_EVENT_BITS) #ifdef CONFIG_MMU_NOTIFIER diff --git a/mm/ksm.c b/mm/ksm.c index 97757c5fa15f..b7fb7b560cc0 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1051,7 +1051,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page, BUG_ON(PageTransCompound(page)); - mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, vma, mm, + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR | + MMU_NOTIFIER_USE_CHANGE_PTE, vma, mm, pvmw.address, pvmw.address + PAGE_SIZE); mmu_notifier_invalidate_range_start(&range); @@ -1140,7 +1141,8 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, if (!pmd) goto out; - mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, vma, mm, addr, + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR | + MMU_NOTIFIER_USE_CHANGE_PTE, vma, mm, addr, addr + PAGE_SIZE); mmu_notifier_invalidate_range_start(&range); diff --git a/mm/memory.c b/mm/memory.c index a8c6922526f6..daf4b0f92af8 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2275,7 +2275,8 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) __SetPageUptodate(new_page); - mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, vma, mm, + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR | + MMU_NOTIFIER_USE_CHANGE_PTE, vma, mm, vmf->address & PAGE_MASK, (vmf->address & PAGE_MASK) + PAGE_SIZE); mmu_notifier_invalidate_range_start(&range); -- 2.17.1