Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751585AbbEZGLW (ORCPT ); Tue, 26 May 2015 02:11:22 -0400 Received: from mail.phunq.net ([184.71.0.62]:53013 "EHLO starbase.phunq.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751181AbbEZGLV convert rfc822-to-8bit (ORCPT ); Tue, 26 May 2015 02:11:21 -0400 From: Daniel Phillips To: David Lang Cc: Rik van Riel , Jan Kara , , , , OGAWA Hirofumi Subject: Re: [FYI] tux3: Core changes Date: Mon, 25 May 2015 23:11:11 -0700 User-Agent: Trojita/v0.5-14-g8a2496c; Qt/4.8.6; X11; Linux; Ubuntu 14.04.2 LTS MIME-Version: 1.0 Message-ID: <67294911-1776-46b8-916d-0e5642a38725@phunq.net> In-Reply-To: References: <8f886f13-6550-4322-95be-93244ae61045@phunq.net> <55545C2F.8040207@phunq.net> <20150519140045.GA16313@quack.suse.cz> <555B8C79.4090909@phunq.net> <20150520144429.GA17783@quack.suse.cz> <555CB4B6.8050305@phunq.net> <555CE62C.5030202@redhat.com> <555D0FDF.3070303@phunq.net> <555D500B.4080901@phunq.net> <13c8bcdf-70e8-43d5-a05f-58ad839dbfd0@phunq.net> <5563F5C8.2040806@redhat.com> Organization: tux3.org Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 917 Lines: 24 On Monday, May 25, 2015 11:04:39 PM PDT, David Lang wrote: > if the page gets modified again, will that cause any issues? > what if the page gets modified before the copy gets written out, > so that there are two dirty copies of the page in the process of > being written? > > David Lang How is the page going to get modified again? A forked page isn't mapped by a pte, so userspace can't modify it by mmap. The forked page is not in the page cache, so usespace can't modify it by posix file ops. So the writer would have to be in kernel. Tux3 knows what it is doing, so it won't modify the page. What kernel code besides Tux3 will modify the page? Regards, Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/