From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f72.google.com (mail-oi0-f72.google.com [209.85.218.72]) by kanga.kvack.org (Postfix) with ESMTP id CDBD26B0069 for ; Mon, 25 Sep 2017 09:16:19 -0400 (EDT) Received: by mail-oi0-f72.google.com with SMTP id x85so8005827oix.3 for ; Mon, 25 Sep 2017 06:16:19 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id v67si3442331oig.219.2017.09.25.06.16.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 Sep 2017 06:16:19 -0700 (PDT) Subject: Re: [patch] mremap.2: Add description of old_size == 0 functionality References: <20170915213745.6821-1-mike.kravetz@oracle.com> <20170925123508.pzjbe7wgwagnr5li@dhcp22.suse.cz> <20170925125207.4tu24sbpnihljknu@dhcp22.suse.cz> From: Florian Weimer Message-ID: <765cd0cb-aa35-187c-456d-05d8752caa04@redhat.com> Date: Mon, 25 Sep 2017 15:16:09 +0200 MIME-Version: 1.0 In-Reply-To: <20170925125207.4tu24sbpnihljknu@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: 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 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. 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.) Thanks, Florian -- 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