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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, 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,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 9073FC433DB for ; Fri, 22 Jan 2021 21:35:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5598D20684 for ; Fri, 22 Jan 2021 21:35:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730310AbhAVVfW (ORCPT ); Fri, 22 Jan 2021 16:35:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729270AbhAVVbY (ORCPT ); Fri, 22 Jan 2021 16:31:24 -0500 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2AA54C0617A7 for ; Fri, 22 Jan 2021 13:29:38 -0800 (PST) Received: by mail-qv1-xf49.google.com with SMTP id cc1so4850776qvb.3 for ; Fri, 22 Jan 2021 13:29:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=uDt5QiaRM5mlYfIhqKdJ+7LtQg/EC98wfYlQZa2ayoY=; b=cLX1HJfwgurT/SFINy9b1C4eLO7KStKmjCO+6Tvz6AYoxSoW/9vxI6K1FkeMUkNlYa hbAzEe7anZkcsTRyclNKqJFPirg/Q6bj5M2xUwgplPQFd2wQXLooN7RjFCxomitlMc5Q JpFvg47o/SvlwNuBB160isr3t62TOjfye7cK9UUT30kwkMZHOllb5woVZK9QoRzEgg46 uzNYdE2fgFqEIuCqZvcsWtnYxuNJzSHkUh6oA9xH1HgtmUKfRZHJonq+HHrvaRbHAM/D CItWrLrpygCtSGeT9hHQXMyKGcsoUqrYhkW7ko+5jNXGZa2gdzvNtxKKC3r1RcfAlnIy zaqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=uDt5QiaRM5mlYfIhqKdJ+7LtQg/EC98wfYlQZa2ayoY=; b=JKhTpB1H/CcGKBiA+aB8YReYlJY26qgFBevqjEo7ozWS1wOJRJaH1kgXzoLCle+lFc CPQphVGQCa20xYPaHhfPYK3WMcZ8q9eU7CQUKQqU1DVrexgVUk52MI/KJoPhrMH/JiEe bRkjhezk78D0BpElkIdwUQoNg/5NCh0AkHJvpF1QEYVO5P8AcRdweU7r23ROViXvzUaU Uviq6aPWRsx6ZKAh3OjNtnZjfrB9AU527TLR4Deha7kYt4VW5kny7Dpdq35znexfGm9e EojM6dMGMKYjUUAaE68saUz3nHWb0mEEgmzo3Kh5jd3QiXM18YkSTjhba0I5Th5wHA7m fF8g== X-Gm-Message-State: AOAM533btPTvZb+g3lKjW8Nk7E8H2PahJ3lNyrPOd9TxB2+I9OezHHFK vs4hXkWbcQ44vXVsRqU/gczcDsaW6sCSzqBMJzBx X-Google-Smtp-Source: ABdhPJy3TkbLobXrNP7oj1ceaOYsSKvn5jm8jx9r64Tmk5tpAR8A3oSERbPNqidWYOTYyyts3wGeoIl/Er2iaeKjRpBu Sender: "axelrasmussen via sendgmr" X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:f693:9fff:feef:c8f8]) (user=axelrasmussen job=sendgmr) by 2002:a05:6214:c65:: with SMTP id t5mr4854565qvj.19.1611350977346; Fri, 22 Jan 2021 13:29:37 -0800 (PST) Date: Fri, 22 Jan 2021 13:29:21 -0800 In-Reply-To: <20210122212926.3457593-1-axelrasmussen@google.com> Message-Id: <20210122212926.3457593-5-axelrasmussen@google.com> Mime-Version: 1.0 References: <20210122212926.3457593-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.30.0.280.ga3ce27912f-goog Subject: [PATCH v2 4/9] hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp From: Axel Rasmussen To: Alexander Viro , Alexey Dobriyan , Andrea Arcangeli , Andrew Morton , Anshuman Khandual , Catalin Marinas , Chinwen Chang , Huang Ying , Ingo Molnar , Jann Horn , Jerome Glisse , Lokesh Gidra , "Matthew Wilcox (Oracle)" , Michael Ellerman , "=?UTF-8?q?Michal=20Koutn=C3=BD?=" , Michel Lespinasse , Mike Kravetz , Mike Rapoport , Nicholas Piggin , Peter Xu , Shaohua Li , Shawn Anastasio , Steven Rostedt , Steven Price , Vlastimil Babka Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Adam Ruprecht , Axel Rasmussen , Cannon Matthews , "Dr . David Alan Gilbert" , David Rientjes , Oliver Upton Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Xu Huge pmd sharing for hugetlbfs is racy with userfaultfd-wp because userfaultfd-wp is always based on pgtable entries, so they cannot be shared. Walk the hugetlb range and unshare all such mappings if there is, right before UFFDIO_REGISTER will succeed and return to userspace. This will pair with want_pmd_share() in hugetlb code so that huge pmd sharing is completely disabled for userfaultfd-wp registered range. Signed-off-by: Peter Xu Signed-off-by: Axel Rasmussen --- fs/userfaultfd.c | 45 ++++++++++++++++++++++++++++++++++++ include/linux/mmu_notifier.h | 1 + 2 files changed, 46 insertions(+) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 894cc28142e7..2c6706ac2504 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -1190,6 +1191,47 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf, } } +/* + * This function will unconditionally remove all the shared pmd pgtable entries + * within the specific vma for a hugetlbfs memory range. + */ +static void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) +{ +#ifdef CONFIG_HUGETLB_PAGE + struct hstate *h = hstate_vma(vma); + unsigned long sz = huge_page_size(h); + struct mm_struct *mm = vma->vm_mm; + struct mmu_notifier_range range; + unsigned long address; + spinlock_t *ptl; + pte_t *ptep; + + /* + * No need to call adjust_range_if_pmd_sharing_possible(), because + * we're going to operate on the whole vma + */ + mmu_notifier_range_init(&range, MMU_NOTIFY_HUGETLB_UNSHARE, + 0, vma, mm, vma->vm_start, vma->vm_end); + mmu_notifier_invalidate_range_start(&range); + i_mmap_lock_write(vma->vm_file->f_mapping); + for (address = vma->vm_start; address < vma->vm_end; address += sz) { + ptep = huge_pte_offset(mm, address, sz); + if (!ptep) + continue; + ptl = huge_pte_lock(h, mm, ptep); + huge_pmd_unshare(mm, vma, &address, ptep); + spin_unlock(ptl); + } + flush_hugetlb_tlb_range(vma, vma->vm_start, vma->vm_end); + i_mmap_unlock_write(vma->vm_file->f_mapping); + /* + * No need to call mmu_notifier_invalidate_range(), see + * Documentation/vm/mmu_notifier.rst. + */ + mmu_notifier_invalidate_range_end(&range); +#endif +} + static void __wake_userfault(struct userfaultfd_ctx *ctx, struct userfaultfd_wake_range *range) { @@ -1448,6 +1490,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, vma->vm_flags = new_flags; vma->vm_userfaultfd_ctx.ctx = ctx; + if (is_vm_hugetlb_page(vma) && uffd_disable_huge_pmd_share(vma)) + hugetlb_unshare_all_pmds(vma); + skip: prev = vma; start = vma->vm_end; diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h index b8200782dede..ff50c8528113 100644 --- a/include/linux/mmu_notifier.h +++ b/include/linux/mmu_notifier.h @@ -51,6 +51,7 @@ enum mmu_notifier_event { MMU_NOTIFY_SOFT_DIRTY, MMU_NOTIFY_RELEASE, MMU_NOTIFY_MIGRATE, + MMU_NOTIFY_HUGETLB_UNSHARE, }; #define MMU_NOTIFIER_RANGE_BLOCKABLE (1 << 0) -- 2.30.0.280.ga3ce27912f-goog