From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E99C9C43381 for ; Thu, 21 Feb 2019 18:28:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C053A20818 for ; Thu, 21 Feb 2019 18:28:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728315AbfBUS2e (ORCPT ); Thu, 21 Feb 2019 13:28:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59138 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726155AbfBUS2e (ORCPT ); Thu, 21 Feb 2019 13:28:34 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9EE1B5AFE3; Thu, 21 Feb 2019 18:28:33 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.236]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 590065D704; Thu, 21 Feb 2019 18:28:27 +0000 (UTC) Date: Thu, 21 Feb 2019 13:28:25 -0500 From: Jerome Glisse To: Peter Xu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Hildenbrand , Hugh Dickins , Maya Gokhale , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Shaohua Li , Marty McFadden , Andrea Arcangeli , Mike Kravetz , Denis Plotnikov , Mike Rapoport , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" Subject: Re: [PATCH v2 21/26] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Message-ID: <20190221182825.GA4198@redhat.com> References: <20190212025632.28946-1-peterx@redhat.com> <20190212025632.28946-22-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190212025632.28946-22-peterx@redhat.com> User-Agent: Mutt/1.10.0 (2018-05-17) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 21 Feb 2019 18:28:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 12, 2019 at 10:56:27AM +0800, Peter Xu wrote: > From: Andrea Arcangeli > > v1: From: Shaohua Li > > v2: cleanups, remove a branch. > > [peterx writes up the commit message, as below...] > > This patch introduces the new uffd-wp APIs for userspace. > > Firstly, we'll allow to do UFFDIO_REGISTER with write protection > tracking using the new UFFDIO_REGISTER_MODE_WP flag. Note that this > flag can co-exist with the existing UFFDIO_REGISTER_MODE_MISSING, in > which case the userspace program can not only resolve missing page > faults, and at the same time tracking page data changes along the way. > > Secondly, we introduced the new UFFDIO_WRITEPROTECT API to do page > level write protection tracking. Note that we will need to register > the memory region with UFFDIO_REGISTER_MODE_WP before that. > > Signed-off-by: Andrea Arcangeli > [peterx: remove useless block, write commit message, check against > VM_MAYWRITE rather than VM_WRITE when register] > Signed-off-by: Peter Xu I am not an expert with userfaultfd code but it looks good to me so: Also see my question down below, just a minor one. Reviewed-by: Jérôme Glisse > --- > fs/userfaultfd.c | 82 +++++++++++++++++++++++++------- > include/uapi/linux/userfaultfd.h | 11 +++++ > 2 files changed, 77 insertions(+), 16 deletions(-) > [...] > diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h > index 297cb044c03f..1b977a7a4435 100644 > --- a/include/uapi/linux/userfaultfd.h > +++ b/include/uapi/linux/userfaultfd.h > @@ -52,6 +52,7 @@ > #define _UFFDIO_WAKE (0x02) > #define _UFFDIO_COPY (0x03) > #define _UFFDIO_ZEROPAGE (0x04) > +#define _UFFDIO_WRITEPROTECT (0x06) > #define _UFFDIO_API (0x3F) What did happen to ioctl 0x05 ? :)