Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755978AbYBGIDR (ORCPT ); Thu, 7 Feb 2008 03:03:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751284AbYBGIDF (ORCPT ); Thu, 7 Feb 2008 03:03:05 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:47626 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751144AbYBGIDE (ORCPT ); Thu, 7 Feb 2008 03:03:04 -0500 Date: Thu, 7 Feb 2008 09:02:45 +0100 From: Ingo Molnar To: Balaji Rao Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , jesse.barnes@intel.com, yhlu.kernel@gmail.com, ak@suse.de, Yinghai Lu Subject: Re: [PATCH][Regression] x86, 32-bit: trim memory not covered by wb mtrrs - FIX Message-ID: <20080207080245.GA28631@elte.hu> References: <200802071257.51893.balajirrao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200802071257.51893.balajirrao@gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3778 Lines: 115 * Balaji Rao wrote: > Hello, > > The following commit caused my X server to stop working. > > commit 99fc8d424bc5d803fe92cad56c068fe64e73747a > Author: Jesse Barnes > Date: Wed Jan 30 13:33:18 2008 +0100 > > x86, 32-bit: trim memory not covered by wb mtrrs > > This patch fixes the improper handling of addresses > 4G by > mtrr_trim_uncached_memory. This, now brings up X on my system. thanks. Incidentally this same bug was reported and fixed yesterday, and that fix is upstream already. Could you please compare your solution to Yinghai Lu's fix below, and send us a patch for any further improvements (or cleanups) you might notice in that code? It seems to be almost the same fix as yours. (and hopefully it fixes your X problem too) Ingo ------------------> commit 20651af9ac60fd6e31360688ad44861a7d05256a Author: Yinghai Lu Date: Wed Feb 6 22:39:45 2008 +0100 x86: fix mttr trimming Pavel Emelyanov reported that his networking card did not work and bisected it down to: " The commit 093af8d7f0ba3c6be1485973508584ef081e9f93 x86_32: trim memory by updating e820 broke my e1000 card: on loading driver says that e1000: probe of 0000:04:03.0 failed with error -5 and the interface doesn't appear. " on a 32-bit kernel, base will overflow when try to do PAGE_SHIFT, and highest_addr will always less 4G. So use pfn instead of address to avoid the overflow when more than 4g RAM is installed on a 32-bit kernel. Many thanks to Pavel Emelyanov for reporting and testing it. Bisected-by: Pavel Emelyanov Signed-off-by: Yinghai Lu Tested-by: Pavel Emelyanov Signed-off-by: Ingo Molnar diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c index 1e27b69..b6e136f 100644 --- a/arch/x86/kernel/cpu/mtrr/main.c +++ b/arch/x86/kernel/cpu/mtrr/main.c @@ -659,7 +659,7 @@ static __init int amd_special_default_mtrr(void) */ int __init mtrr_trim_uncached_memory(unsigned long end_pfn) { - unsigned long i, base, size, highest_addr = 0, def, dummy; + unsigned long i, base, size, highest_pfn = 0, def, dummy; mtrr_type type; u64 trim_start, trim_size; @@ -682,28 +682,27 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn) mtrr_if->get(i, &base, &size, &type); if (type != MTRR_TYPE_WRBACK) continue; - base <<= PAGE_SHIFT; - size <<= PAGE_SHIFT; - if (highest_addr < base + size) - highest_addr = base + size; + if (highest_pfn < base + size) + highest_pfn = base + size; } /* kvm/qemu doesn't have mtrr set right, don't trim them all */ - if (!highest_addr) { + if (!highest_pfn) { printk(KERN_WARNING "WARNING: strange, CPU MTRRs all blank?\n"); WARN_ON(1); return 0; } - if ((highest_addr >> PAGE_SHIFT) < end_pfn) { + if (highest_pfn < end_pfn) { printk(KERN_WARNING "WARNING: BIOS bug: CPU MTRRs don't cover" - " all of memory, losing %LdMB of RAM.\n", - (((u64)end_pfn << PAGE_SHIFT) - highest_addr) >> 20); + " all of memory, losing %luMB of RAM.\n", + (end_pfn - highest_pfn) >> (20 - PAGE_SHIFT)); WARN_ON(1); printk(KERN_INFO "update e820 for mtrr\n"); - trim_start = highest_addr; + trim_start = highest_pfn; + trim_start <<= PAGE_SHIFT; trim_size = end_pfn; trim_size <<= PAGE_SHIFT; trim_size -= trim_start; -- 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/