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 9B8DCC282DB for ; Mon, 21 Jan 2019 07:59:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7610F20823 for ; Mon, 21 Jan 2019 07:59:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729366AbfAUH7t (ORCPT ); Mon, 21 Jan 2019 02:59:49 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48554 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728085AbfAUH7s (ORCPT ); Mon, 21 Jan 2019 02:59:48 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9AE09806B6; Mon, 21 Jan 2019 07:59:47 +0000 (UTC) Received: from xz-x1.nay.redhat.com (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4B9F5608F3; Mon, 21 Jan 2019 07:59:39 +0000 (UTC) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hugh Dickins , Maya Gokhale , Jerome Glisse , Johannes Weiner , peterx@redhat.com, Martin Cracauer , Denis Plotnikov , Shaohua Li , Andrea Arcangeli , Pavel Emelyanov , Mike Kravetz , Marty McFadden , Mike Rapoport , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" Subject: [PATCH RFC 17/24] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Date: Mon, 21 Jan 2019 15:57:15 +0800 Message-Id: <20190121075722.7945-18-peterx@redhat.com> In-Reply-To: <20190121075722.7945-1-peterx@redhat.com> References: <20190121075722.7945-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 21 Jan 2019 07:59:47 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org UFFD_EVENT_FORK support for uffd-wp should be already there, except that we should clean the uffd-wp bit if uffd fork event is not enabled. Detect that to avoid _PAGE_UFFD_WP being set even if the VMA is not being tracked by VM_UFFD_WP. Do this for both small PTEs and huge PMDs. Signed-off-by: Peter Xu --- mm/huge_memory.c | 8 ++++++++ mm/memory.c | 8 ++++++++ 2 files changed, 16 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 169795c8e56c..2a3ec62e83b6 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -928,6 +928,14 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, ret = -EAGAIN; pmd = *src_pmd; + /* + * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA + * does not have the VM_UFFD_WP, which means that the uffd + * fork event is not enabled. + */ + if (!(vma->vm_flags & VM_UFFD_WP)) + pmd = pmd_clear_uffd_wp(pmd); + #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION if (unlikely(is_swap_pmd(pmd))) { swp_entry_t entry = pmd_to_swp_entry(pmd); diff --git a/mm/memory.c b/mm/memory.c index a3de13b728f4..f5497752d2a3 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -788,6 +788,14 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, pte = pte_mkclean(pte); pte = pte_mkold(pte); + /* + * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA + * does not have the VM_UFFD_WP, which means that the uffd + * fork event is not enabled. + */ + if (!(vm_flags & VM_UFFD_WP)) + pte = pte_clear_uffd_wp(pte); + page = vm_normal_page(vma, addr, pte); if (page) { get_page(page); -- 2.17.1