From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id 9738A6B0258 for ; Thu, 19 Nov 2015 17:34:04 -0500 (EST) Received: by pabfh17 with SMTP id fh17so97455315pab.0 for ; Thu, 19 Nov 2015 14:34:04 -0800 (PST) Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com. [67.231.145.42]) by mx.google.com with ESMTPS id l29si77010pfi.75.2015.11.19.14.33.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Nov 2015 14:33:56 -0800 (PST) Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.15.0.59/8.15.0.59) with SMTP id tAJMTZrC012940 for ; Thu, 19 Nov 2015 14:33:56 -0800 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 1y9nywgawm-2 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT) for ; Thu, 19 Nov 2015 14:33:56 -0800 Received: from facebook.com (2401:db00:11:d0a2:face:0:39:0) by mx-out.facebook.com (10.102.107.99) with ESMTP id 9d0d9ee28f0d11e5b9600002c99293a0-495fa230 for ; Thu, 19 Nov 2015 14:33:53 -0800 From: Shaohua Li Subject: [RFC 4/8] userfaultfd: allow userfaultfd register success with writeprotection Date: Thu, 19 Nov 2015 14:33:49 -0800 Message-ID: <1735e26d3649be909e89d1d3c3e2d27604788d79.1447964595.git.shli@fb.com> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: kernel-team@fb.com, Andrew Morton , Andrea Arcangeli , Pavel Emelyanov , Rik van Riel , "Kirill A. Shutemov" , Mel Gorman , Hugh Dickins , Johannes Weiner The userfaultfd register ioctl currently disables writeprotection. Enable it. Cc: Andrea Arcangeli Cc: Pavel Emelyanov Cc: Rik van Riel Cc: Kirill A. Shutemov Cc: Mel Gorman Cc: Hugh Dickins Cc: Johannes Weiner Signed-off-by: Shaohua Li --- fs/userfaultfd.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index eaa5086..12176b5 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -236,6 +236,8 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, */ if (pte_none(*pte)) ret = true; + if (!pte_write(*pte) && (reason & VM_UFFD_WP)) + ret = true; pte_unmap(pte); out: @@ -736,15 +738,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, vm_flags = 0; if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) vm_flags |= VM_UFFD_MISSING; - if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) { + if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) vm_flags |= VM_UFFD_WP; - /* - * FIXME: remove the below error constraint by - * implementing the wprotect tracking mode. - */ - ret = -EINVAL; - goto out; - } ret = validate_range(mm, uffdio_register.range.start, uffdio_register.range.len); @@ -784,6 +779,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, ret = -EINVAL; if (cur->vm_ops) goto out_unlock; + if ((vm_flags & VM_UFFD_WP) && !(cur->vm_flags & VM_WRITE)) + goto out_unlock; /* * Check that this vma isn't already owned by a -- 2.4.6 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org