From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f200.google.com (mail-qk0-f200.google.com [209.85.220.200]) by kanga.kvack.org (Postfix) with ESMTP id C2A974403E0 for ; Wed, 8 Nov 2017 01:54:19 -0500 (EST) Received: by mail-qk0-f200.google.com with SMTP id 78so1333173qkz.13 for ; Tue, 07 Nov 2017 22:54:19 -0800 (PST) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id t30si410359qtg.264.2017.11.07.22.54.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Nov 2017 22:54:18 -0800 (PST) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vA86qwBP127692 for ; Wed, 8 Nov 2017 01:54:17 -0500 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0a-001b2d01.pphosted.com with ESMTP id 2e3ptnh96b-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 08 Nov 2017 01:54:17 -0500 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 8 Nov 2017 06:54:15 -0000 From: Mike Rapoport Subject: [PATCH] userfaultfd.2: document spurious UFFD_EVENT_FORK Date: Wed, 8 Nov 2017 08:54:08 +0200 Message-Id: <1510124048-7991-1-git-send-email-rppt@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Michael Kerrisk Cc: Andrea Arcangeli , linux-man@vger.kernel.org, linux-mm , Mike Rapoport Signed-off-by: Mike Rapoport --- man2/userfaultfd.2 | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 index 1c9e64b..08c41e1 100644 --- a/man2/userfaultfd.2 +++ b/man2/userfaultfd.2 @@ -465,6 +465,16 @@ for checkpoint/restore mechanisms, as well as post-copy migration to allow (nearly) uninterrupted execution when transferring virtual machines and Linux containers from one host to another. +.SH BUGS +If the +.B UFFD_FEATURE_EVENT_FORK +is enabled and a system call from the +.BR fork (2) +family is interrupted by a signal or failed,q a stale userfaultfd descriptor +might be created. +In this case a spurious +.B UFFD_EVENT_FORK +will be delivered to the userfaultfd monitor. .SH EXAMPLE The program below demonstrates the use of the userfaultfd mechanism. The program creates two threads, one of which acts as the -- 2.7.4 -- 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