Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751895AbbEZIJL (ORCPT ); Tue, 26 May 2015 04:09:11 -0400 Received: from mail.phunq.net ([184.71.0.62]:43228 "EHLO starbase.phunq.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751738AbbEZIJI convert rfc822-to-8bit (ORCPT ); Tue, 26 May 2015 04:09:08 -0400 From: Daniel Phillips To: Jan Kara Cc: David Lang , Rik van Riel , , , , OGAWA Hirofumi Subject: Re: [FYI] tux3: Core changes Date: Tue, 26 May 2015 01:08:56 -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: In-Reply-To: <20150526070910.GA3307@quack.suse.cz> References: <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> <67294911-1776-46b8-916d-0e5642a38725@phunq.net> <20150526070910.GA3307@quack.suse.cz> 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: 953 Lines: 23 On Tuesday, May 26, 2015 12:09:10 AM PDT, Jan Kara wrote: > E.g. video drivers (or infiniband or direct IO for that matter) which > have buffers in user memory (may be mmapped file), grab references to pages > and hand out PFNs of those pages to the hardware to store data in them... > If you fork a page after the driver has handed PFNs to the hardware, you've > just lost all the writes hardware will do. Hi Jan, The page forked because somebody wrote to it with write(2) or mmap write at the same time as a video driver (or infiniband or direct IO) was doing io to it. Isn't the application trying hard to lose data in that case? It would not need page fork to lose data that way. 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/