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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 58350C433C1 for ; Tue, 23 Mar 2021 00:51:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 31C48619AC for ; Tue, 23 Mar 2021 00:51:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231634AbhCWAvh (ORCPT ); Mon, 22 Mar 2021 20:51:37 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:42125 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231661AbhCWAu5 (ORCPT ); Mon, 22 Mar 2021 20:50:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616460656; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QYSwV1DdjoGbYhLD7l7jd/ThoyIb5S4HvnYDjWOs2EQ=; b=P2WKWSsbTUWFBTnEUw005A41QKzl/gP56VEeoAvinnRAQ9anGP5nS82Vg2e0kn/4cd7hDU kmPNiN7QVBm/1OPhD8HfzaFF1wB2qWdV44C8sgrBuCQYETC8JPoNiGAy1TfE2SrPAzDrSG d3HOnH+3CdmX62mlMmljk2m9rncCI2E= Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-556-94h6BmyzOva8S0VDjeHpRQ-1; Mon, 22 Mar 2021 20:50:55 -0400 X-MC-Unique: 94h6BmyzOva8S0VDjeHpRQ-1 Received: by mail-qt1-f198.google.com with SMTP id m8so394038qtp.14 for ; Mon, 22 Mar 2021 17:50:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=QYSwV1DdjoGbYhLD7l7jd/ThoyIb5S4HvnYDjWOs2EQ=; b=fYgq5p8XqBBEas17LaO/n+uMFCJtz3HVpZaRyjc8kIfuUY3rXymdvJbwDrcY/TqoXh n/IJaLjYU3XgUcNmYvlKA+5o6K/laRjMkruGk9HwJNY+G3qkRXRaS3l8odJxA3m20Kr9 nFAEsxU+CTP9ApoWg/IMxvV+kFZ5flOBz8xt7xUdESHCMcUcSH26IuZ+INPtPWMLwdQm FHa6KPWAaNca+LNyDK++ZqNvh2Rjff80mg0rQODpey/AbZNyeGFkZDe3KlGT1dX3t10N WK1cHx79JqqZ6BTjDBa3Gba0lTYWSjLxTaEdsKGa+FtmgvZ5T9XbWXQt1Dqe1uU/AWnP YwLw== X-Gm-Message-State: AOAM533uzPB7iys7qp18eXF7D8OkV6cDk8xg5wllm/9oxQ/Movmf6Mam p6Hxj4z7eO+B0fBRBH/3HGAzF3PTYBnUrMl9wFWlNrwxSHK5HTSJJAGSgshWu4G8h6nkccEWSun Z7QHghOTrUUCg6Zz5gyC0pb5g X-Received: by 2002:ad4:4cc8:: with SMTP id i8mr2460896qvz.56.1616460654756; Mon, 22 Mar 2021 17:50:54 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz/wYGS6MPDtkctKR6iln/9KAo2nZVmqKkBxLuPXgL5Im3S3NO0Z0sGaNw2LONKOI8LyEdDOw== X-Received: by 2002:ad4:4cc8:: with SMTP id i8mr2460882qvz.56.1616460654532; Mon, 22 Mar 2021 17:50:54 -0700 (PDT) Received: from localhost.localdomain (bras-base-toroon474qw-grc-82-174-91-135-175.dsl.bell.ca. [174.91.135.175]) by smtp.gmail.com with ESMTPSA id 8sm12051921qkc.32.2021.03.22.17.50.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Mar 2021 17:50:54 -0700 (PDT) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Mike Rapoport , Nadav Amit , Jerome Glisse , Hugh Dickins , Andrea Arcangeli , Andrew Morton , "Kirill A . Shutemov" , Axel Rasmussen , peterx@redhat.com, Mike Kravetz , Matthew Wilcox Subject: [PATCH 20/23] hugetlb/userfaultfd: Allow wr-protect none ptes Date: Mon, 22 Mar 2021 20:50:52 -0400 Message-Id: <20210323005052.35916-1-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210323004912.35132-1-peterx@redhat.com> References: <20210323004912.35132-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Teach hugetlbfs code to wr-protect none ptes just in case the page cache existed for that pte. Meanwhile we also need to be able to recognize a uffd-wp marker pte and remove it for uffd_wp_resolve. Since at it, introduce a variable "psize" to replace all references to the huge page size fetcher. Signed-off-by: Peter Xu --- mm/hugetlb.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 448ef745d5ee..d4acf9d9d087 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5110,7 +5110,7 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, pte_t *ptep; pte_t pte; struct hstate *h = hstate_vma(vma); - unsigned long pages = 0; + unsigned long pages = 0, psize = huge_page_size(h); bool shared_pmd = false; struct mmu_notifier_range range; bool uffd_wp = cp_flags & MM_CP_UFFD_WP; @@ -5130,13 +5130,19 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, mmu_notifier_invalidate_range_start(&range); i_mmap_lock_write(vma->vm_file->f_mapping); - for (; address < end; address += huge_page_size(h)) { + for (; address < end; address += psize) { spinlock_t *ptl; - ptep = huge_pte_offset(mm, address, huge_page_size(h)); + ptep = huge_pte_offset(mm, address, psize); if (!ptep) continue; ptl = huge_pte_lock(h, mm, ptep); if (huge_pmd_unshare(mm, vma, &address, ptep)) { + /* + * When uffd-wp is enabled on the vma, unshare + * shouldn't happen at all. Warn about it if it + * happened due to some reason. + */ + WARN_ON_ONCE(uffd_wp || uffd_wp_resolve); pages++; spin_unlock(ptl); shared_pmd = true; @@ -5160,12 +5166,21 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, else if (uffd_wp_resolve) newpte = pte_swp_clear_uffd_wp(newpte); set_huge_swap_pte_at(mm, address, ptep, - newpte, huge_page_size(h)); + newpte, psize); pages++; } spin_unlock(ptl); continue; } + if (unlikely(is_swap_special_pte(pte))) { + WARN_ON_ONCE(!pte_swp_uffd_wp_special(pte)); + /* + * This is changing a non-present pte into a none pte, + * no need for huge_ptep_modify_prot_start/commit(). + */ + if (uffd_wp_resolve) + huge_pte_clear(mm, address, ptep, psize); + } if (!huge_pte_none(pte)) { pte_t old_pte; @@ -5178,6 +5193,12 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, pte = huge_pte_clear_uffd_wp(pte); huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte); pages++; + } else { + /* None pte */ + if (unlikely(uffd_wp)) + /* Safe to modify directly (none->non-present). */ + set_huge_pte_at(mm, address, ptep, + pte_swp_mkuffd_wp_special(vma)); } spin_unlock(ptl); } -- 2.26.2