From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id EEC346B0038 for ; Tue, 31 Jan 2017 19:39:30 -0500 (EST) Received: by mail-pf0-f199.google.com with SMTP id 201so542867175pfw.5 for ; Tue, 31 Jan 2017 16:39:30 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id d20si17502408plj.252.2017.01.31.16.39.29 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 31 Jan 2017 16:39:29 -0800 (PST) Date: Tue, 31 Jan 2017 16:39:28 -0800 From: Andrew Morton Subject: Re: [PATCH v2 2/5] userfaultfd: non-cooperative: add event for memory unmaps Message-Id: <20170131163928.4e4e05fbd93358d9b937d79b@linux-foundation.org> In-Reply-To: <1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com> References: <1485542673-24387-1-git-send-email-rppt@linux.vnet.ibm.com> <1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mike Rapoport Cc: Andrea Arcangeli , "Dr. David Alan Gilbert" , Hillf Danton , Mike Kravetz , Pavel Emelyanov , Linux-MM , LKML On Fri, 27 Jan 2017 20:44:30 +0200 Mike Rapoport wrote: > When a non-cooperative userfaultfd monitor copies pages in the background, > it may encounter regions that were already unmapped. Addition of > UFFD_EVENT_UNMAP allows the uffd monitor to track precisely changes in the > virtual memory layout. > > Since there might be different uffd contexts for the affected VMAs, we > first should create a temporary representation for the unmap event for each > uffd context and then notify them one by one to the appropriate userfault > file descriptors. > > The event notification occurs after the mmap_sem has been released. I was going to bug you about not updating Documentation/vm/userfaultfd.txt but the UFFD_FEATURE flags aren't documented? -- 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