From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263692AbTKRQhf (ORCPT ); Tue, 18 Nov 2003 11:37:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263723AbTKRQhf (ORCPT ); Tue, 18 Nov 2003 11:37:35 -0500 Received: from fw.osdl.org ([65.172.181.6]:31960 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S263692AbTKRQhd (ORCPT ); Tue, 18 Nov 2003 11:37:33 -0500 Date: Tue, 18 Nov 2003 08:37:25 -0800 (PST) From: Linus Torvalds To: Zwane Mwaikambo cc: Ingo Molnar , "Martin J. Bligh" , Andrew Morton , Linux Kernel , , Hugh Dickins Subject: Re: [PATCH][2.6-mm] Fix 4G/4G X11/vm86 oops In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 18 Nov 2003, Zwane Mwaikambo wrote: > > Here are diffs from the do_sys_vm86 only. Ok. Much more readable. And there is something very suspicious there. The code with and without the printk() looks _identical_ apart from some trivial label renumbering, and the added pushl $.LC6 call printk .. asm .. popl %esi which all looks fine (esi is dead at that point, so the compiler is just using a "popl" as a shorter form of "addl $4,%esp"). Btw, you seem to compile with debugging, which makes the assembly language pretty much unreadable and accounts for most of the differences: the line numbers change. If you compile a kernel where the line numbers don't change (by commenting _out_ the printk rather than removing the whole line), your diff would be more readable. Anyway, there are _zero_ differences. Just for fun, try this: move the "printk()" to _below_ the "asm" statement. It will never actually get executed, but if it's an issue of some subtle code or data placement things (cache lines etc), maybe that also hides the oops, since all the same code and data will be generated, just not run... Linus