Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936077AbdIYOyq (ORCPT ); Mon, 25 Sep 2017 10:54:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52184 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936046AbdIYOyn (ORCPT ); Mon, 25 Sep 2017 10:54:43 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com D987381E07 Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=fweimer@redhat.com Subject: Re: [patch] mremap.2: Add description of old_size == 0 functionality To: Michal Hocko Cc: Mike Kravetz , mtk.manpages@gmail.com, linux-man@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Andrea Arcangeli , "Kirill A . Shutemov" , Vlastimil Babka , Anshuman Khandual , linux-mm@kvack.org References: <20170915213745.6821-1-mike.kravetz@oracle.com> <20170925123508.pzjbe7wgwagnr5li@dhcp22.suse.cz> <20170925125207.4tu24sbpnihljknu@dhcp22.suse.cz> <765cd0cb-aa35-187c-456d-05d8752caa04@redhat.com> <20170925145238.gic2n37ffc6ytyvx@dhcp22.suse.cz> From: Florian Weimer Message-ID: Date: Mon, 25 Sep 2017 16:54:39 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20170925145238.gic2n37ffc6ytyvx@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 25 Sep 2017 14:54:43 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 555 Lines: 16 On 09/25/2017 04:52 PM, Michal Hocko wrote: > On Mon 25-09-17 15:16:09, Florian Weimer wrote: >> On 09/25/2017 02:52 PM, Michal Hocko wrote: >>> So, how are you going to deal with the CoW and the implementation which >>> basically means that the newm mmap content is not the same as the >>> original one? >> >> I don't understand why CoW would kick in. > > So you can guarantee nobody is going to write to that memory? It's mapped readable and executable, but not writable. So the only thing that could interfere would be a debugger. Thanks, Florian