From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id C13B06B02F3 for ; Mon, 1 May 2017 01:43:37 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id r190so6616652wme.16 for ; Sun, 30 Apr 2017 22:43:37 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com. [148.163.158.5]) by mx.google.com with ESMTPS id r66si7674632wma.48.2017.04.30.22.43.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 30 Apr 2017 22:43:36 -0700 (PDT) Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v415hUVN078798 for ; Mon, 1 May 2017 01:43:35 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0b-001b2d01.pphosted.com with ESMTP id 2a5vuxbmet-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 01 May 2017 01:43:35 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 1 May 2017 06:43:33 +0100 From: Mike Rapoport Subject: [PATCH man-pages 3/5] ioctl_userfaultfd.2: add BUGS section Date: Mon, 1 May 2017 08:43:17 +0300 In-Reply-To: <1493617399-20897-1-git-send-email-rppt@linux.vnet.ibm.com> References: <1493617399-20897-1-git-send-email-rppt@linux.vnet.ibm.com> Message-Id: <1493617399-20897-4-git-send-email-rppt@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Michael Kerrisk (man-pages)" Cc: Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-man@vger.kernel.org, Mike Rapoport The features handshake is not quite convenient. Elaborate about it in the BUGS section. Signed-off-by: Mike Rapoport --- man2/ioctl_userfaultfd.2 | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/man2/ioctl_userfaultfd.2 b/man2/ioctl_userfaultfd.2 index e12b9de..50316de 100644 --- a/man2/ioctl_userfaultfd.2 +++ b/man2/ioctl_userfaultfd.2 @@ -650,6 +650,15 @@ operations are Linux-specific. .SH EXAMPLE See .BR userfaultfd (2). +.SH BUGS +In order to detect available userfault features and +enable certain subset of those features +the usefault file descriptor must be closed after the first +.BR UFFDIO_API +operation that queries features availability and re-opened before +the second +.BR UFFDIO_API +call that actually enables the desired features. .SH SEE ALSO .BR ioctl (2), .BR mmap (2), -- 1.9.1 -- 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