Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753523AbbKCOLj (ORCPT ); Tue, 3 Nov 2015 09:11:39 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:34326 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751880AbbKCOLd (ORCPT ); Tue, 3 Nov 2015 09:11:33 -0500 Date: Tue, 3 Nov 2015 14:06:16 +0000 From: Matt Fleming To: Ingo Molnar Cc: kernel test robot , Paolo Bonzini , lkp@01.org, LKML , Andy Lutomirski , Thomas Gleixner , "H. Peter Anvin" , Borislav Petkov , Laszlo Ersek Subject: Re: [lkp] [x86/setup] f5f3497cad: BUG: kernel boot crashed Message-ID: <20151103140354.GA2653@codeblueprint.co.uk> References: <87io5rpn1c.fsf@yhuang-dev.intel.com> <20151102162551.GB2331@codeblueprint.co.uk> <20151103080734.GA20008@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151103080734.GA20008@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2146 Lines: 63 On Tue, 03 Nov, at 09:07:34AM, Ingo Molnar wrote: > > Unfortunately this commit is now part of the v4.3 kernel, so we need a quick > solution or a quick revert. Quick solution: --- >From ebb589d9cd83cce838d540aea1951d9b902eb0bc Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Tue, 3 Nov 2015 13:40:41 +0000 Subject: [PATCH] x86/setup: Fix recent boot crash on 32-bit SMP machines The LKP test robot reported that the bug fix in commit f5f3497cad8c ("x86/setup: Extend low identity map to cover whole kernel range") causes CONFIG_X86_32 SMP machines to crash on boot when trying to bring AP cpus online. The above commit erroneously copies too many of the PGD entries to the low memory region of 'identity_page_table', resulting in some of the kernel mappings for PAGE_OFFSET being trashed because, KERNEL_PGD_PTRS > KERNEL_PGD_BOUNDARY The maximum number of PGD entries we can copy without corrupting the kernel mapping is KERNEL_PGD_BOUNDARY or pgd_index(PAGE_OFFSET). Reported-by: Ying Huang Cc: Paolo Bonzini Cc: Laszlo Ersek Cc: Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Andy Lutomirski Signed-off-by: Matt Fleming --- arch/x86/kernel/setup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index a3cccbfc5f77..2b8cbd693da8 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1180,7 +1180,7 @@ void __init setup_arch(char **cmdline_p) */ clone_pgd_range(initial_page_table, swapper_pg_dir + KERNEL_PGD_BOUNDARY, - KERNEL_PGD_PTRS); + KERNEL_PGD_BOUNDARY); #endif tboot_probe(); -- 2.6.2 -- 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/