From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 492A66B0038 for ; Mon, 25 Sep 2017 10:52:41 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id c23so1117827wrg.16 for ; Mon, 25 Sep 2017 07:52:41 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id j97si5258699wrj.386.2017.09.25.07.52.39 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 25 Sep 2017 07:52:39 -0700 (PDT) Date: Mon, 25 Sep 2017 16:52:38 +0200 From: Michal Hocko Subject: Re: [patch] mremap.2: Add description of old_size == 0 functionality Message-ID: <20170925145238.gic2n37ffc6ytyvx@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <765cd0cb-aa35-187c-456d-05d8752caa04@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Florian Weimer 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 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? Moreover for the anonymous mapping you really get zero pages rather than the original content AFAIR. > The approach I outlined is > desirable because it avoids the need to modify any executable pages, so this > is not a concern. The point is to create a potentially unbounded number of > thunks *without* run-time code generation. > > If the file is rewritten on disk, that's already undefined today, so it's > not something we need to be concerned with. (Anything which replaces ELF > files needs to use the rename-into-place approach anyway.) Yeah that part is not all that interesting. -- Michal Hocko SUSE Labs -- 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