Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758909AbYFQVPk (ORCPT ); Tue, 17 Jun 2008 17:15:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758010AbYFQVPO (ORCPT ); Tue, 17 Jun 2008 17:15:14 -0400 Received: from one.firstfloor.org ([213.235.205.2]:33352 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757935AbYFQVPN (ORCPT ); Tue, 17 Jun 2008 17:15:13 -0400 Message-ID: <4858295D.8000904@firstfloor.org> Date: Tue, 17 Jun 2008 23:15:09 +0200 From: Andi Kleen User-Agent: Thunderbird 1.5.0.12 (X11/20060911) MIME-Version: 1.0 To: Linus Torvalds CC: Bron Gondwana , Linux Kernel Mailing List , Nick Piggin , Andrew Morton , Rob Mueller , Ingo Molnar Subject: Re: BUG: mmapfile/writev spurious zero bytes (x86_64/not i386, bisected, reproducable) References: <1213682410.13174.1258837181@webmail.messagingengine.com> <1213682570.13708.1258839317@webmail.messagingengine.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 754 Lines: 23 Linus Torvalds wrote: > > On Tue, 17 Jun 2008, Linus Torvalds wrote: >> I actually am starting to think that the bug is in >> __copy_to_user_inatomic_nocache(). > > Confirmed. > > The uncached user copies are totally broken. The number of bytes left > uncopied is simply wrong, because of how it does that unrolled loop and > doesn't account for the fact that just doing loads does not actually > increase the number of bytes copied at all. How can a load fault legitimately in copy_to_user? -Andi -- 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/