From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752759AbYIJQtj (ORCPT ); Wed, 10 Sep 2008 12:49:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752216AbYIJQta (ORCPT ); Wed, 10 Sep 2008 12:49:30 -0400 Received: from gw.goop.org ([64.81.55.164]:38112 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752009AbYIJQta (ORCPT ); Wed, 10 Sep 2008 12:49:30 -0400 Message-ID: <48C7FA91.9050302@goop.org> Date: Wed, 10 Sep 2008 09:49:21 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.16 (X11/20080723) MIME-Version: 1.0 To: Ingo Molnar CC: linux-kernel@vger.kernel.org, Thomas Gleixner , "H. Peter Anvin" Subject: Re: [PATCH 6 of 7] x86: use early_ioremap in __acpi_map_table References: <944fe7ea3da7707eb90f.1220826078@localhost> <20080907234418.GB26079@one.firstfloor.org> <48C46BCB.2060209@goop.org> <20080908142619.GA10580@elte.hu> <20080910115525.GA31692@elte.hu> In-Reply-To: <20080910115525.GA31692@elte.hu> X-Enigmail-Version: 0.95.7 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 Ingo Molnar wrote: >> So i'd suggest a different, more carful approach: keep the new code >> you wrote, but print a WARN()ing if prev_map is not unmapped yet when >> the next mapping is acquired. That way the ACPI code can be fixed >> gradually and without breaking existing functionality. >> > > ok, i stuck in your patches into tip/master today and -tip testing > quickly found an early-ioremap leak: > > [ 36.625100] calling check_early_ioremap_leak+0x0/0x3d > [ 36.630253] ------------[ cut here ]------------ > [ 36.634884] WARNING: at arch/x86/mm/ioremap.c:577 check_early_ioremap_leak+0x28/0x3d() > [ 36.642811] Debug warning: early ioremap leak of 1 areas detected. > > find the full log below with ioremap-leak-tracing turned on. I've > excluded these commits for now from tip/master. > Yes, that leak is expected, unfortunately. __acpi_map_table() has no corresponding unmap, and only maintains one mapping. So it will leak its last mapping when it switches over from using __acpi_map_table() to ioremap(). So, yes, its ugly, but its guaranteed to be a single leaked mapping. But I'm not sure what the best approach to deal with it is. (All those other backtraces are just informational, right?) J