Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758950AbYFQVay (ORCPT ); Tue, 17 Jun 2008 17:30:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756218AbYFQVar (ORCPT ); Tue, 17 Jun 2008 17:30:47 -0400 Received: from one.firstfloor.org ([213.235.205.2]:58122 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752803AbYFQVaq (ORCPT ); Tue, 17 Jun 2008 17:30:46 -0400 Message-ID: <48582D04.1000107@firstfloor.org> Date: Tue, 17 Jun 2008 23:30:44 +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> <485829A1.4020705@firstfloor.org> 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: 1489 Lines: 38 Linus Torvalds wrote: > > On Tue, 17 Jun 2008, Andi Kleen wrote: >> If that fixes anything: >> - The caller is broken because it shouldn't pass a faulting source to copy_to_user() >> - And you broken copy_from_user error reporting which shares the same code > > Andi, I'm sorry I cc'd you. You are the author of that crap, but the bug > seems to be that you never even understood what copy_from_user() is > supposed to do. > > The whole *and*only* reason for copy_to/from_user() existing AT ALL is > exactly the fact that the source or destination access can fault. yes, but only one of them (destination for copy_to_user and source for copy_from_user) Or are you're describing copy_in_user()? > I don't really see why you continually start arguing about things that are > OBVIOUSLY BUGGY, as if they weren't buggy. Once somebody has debugged a > buggy routine, you shouldn't argue against it. > > So here's a hint: next time I claim some code of yours is buggy, either > just acknowledge the bug, or stay silent. You'll look smarter that way. Ok if I'm really wrong on this (but frankly I don't see the mistake, sorry) for my person edification: what's a legitimate case for copy_to_user() where the source can fault? -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/