From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id 0A0686B02F4 for ; Mon, 1 May 2017 01:43:39 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id q25so68090392pfg.6 for ; Sun, 30 Apr 2017 22:43:39 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id s65si13371220pgb.37.2017.04.30.22.43.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 30 Apr 2017 22:43:38 -0700 (PDT) Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v415hXul057161 for ; Mon, 1 May 2017 01:43:37 -0400 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 2a5sbb97s5-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 01 May 2017 01:43:37 -0400 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 1 May 2017 06:43:35 +0100 From: Mike Rapoport Subject: [PATCH man-pages 4/5] userfaultfd.2: add note about asynchronios events delivery Date: Mon, 1 May 2017 08:43:18 +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: <1493617399-20897-5-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 Signed-off-by: Mike Rapoport --- man2/userfaultfd.2 | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 index 8b89162..f177bba 100644 --- a/man2/userfaultfd.2 +++ b/man2/userfaultfd.2 @@ -112,6 +112,18 @@ created for the child process, which allows userfaultfd monitor to perform user-space paging for the child process. +Unlike page faults which have to be synchronous and require +explicit or implicit wakeup, +all other events are delivered asynchronously and +the non-cooperative process resumes execution as +soon as manager executes +.BR read(2). +The userfaultfd manager should carefully synchronize calls +to UFFDIO_COPY with the events processing. + +The current asynchronous model of the event delivery is optimal for +single threaded non-cooperative userfaultfd manager implementations. + .\" FIXME elaborate about non-cooperating mode, describe its limitations .\" for kernels before 4.11, features added in 4.11 .\" and limitations remaining in 4.11 -- 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