Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757274Ab2JRQ2E (ORCPT ); Thu, 18 Oct 2012 12:28:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40845 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757237Ab2JRQ2C (ORCPT ); Thu, 18 Oct 2012 12:28:02 -0400 Date: Thu, 18 Oct 2012 13:27:46 -0300 From: Flavio Leitner To: Dave Young Cc: Dave Young , Ingo Molnar , Yinghai Lu , Dan Carpenter , Cong Wang , lkml , Ingo Molnar , Tejun Heo , ianfang.cn@gmail.com, Andrew Morton , Vivek Goyal Subject: Re: kexec/kdump kernel fails to start Message-ID: <20121018132746.66a6bf1d@obelix.rh> In-Reply-To: <507FA2B3.3080403@redhat.com> References: <20120904143215.5bbbb2a4@obelix.rh> <20120923202727.GA28937@mwanda> <20120929071318.GA7444@gmail.com> <507FA2B3.3080403@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3761 Lines: 102 On Thu, 18 Oct 2012 14:33:23 +0800 Dave Young wrote: [...] > Just see Yinghai's coments, later init_memory_mapping cleanup > will also address the 4k pages in first 2/4M, so revert them should be better. > https://lkml.org/lkml/2012/9/4/533 > > Here is a patch for the reverting: > --- > x86 mm: Revert find_early_table_space fix > > 722bc6b16771ed80871e1fd81c86d3627dda2ac8 Try to address the issue that the > first 2/4M should use 4k pages if PSE enabled. but extra counts should only > valid for x86_32. This commit cause kdump regression, kdump kernel hangs happens > with it. > > As Yinghai Lu said they should be reverted. see below post: > https://lkml.org/lkml/2012/9/4/533 > > As there's a later fix to above fix which is bd2753b2dda7bb43c7468826de75f49c6a7e8965 > So we need revert both of these two commits. > > Tested kdump on physical and virutual machines. > > Reverted commits: > commit 722bc6b16771ed80871e1fd81c86d3627dda2ac8 > Author: WANG Cong > Date: Mon Mar 5 15:05:13 2012 -0800 > > x86/mm: Fix the size calculation of mapping tables > > For machines that enable PSE, the first 2/4M memory region still uses > 4K pages, so needs more PTEs in this case, but > find_early_table_space() doesn't count this. > > This patch fixes it. > > The bug was found via code review, no misbehavior of the kernel > was observed. > > Signed-off-by: WANG Cong > Cc: Yinghai Lu > Cc: Tejun Heo > Cc: > Signed-off-by: Andrew Morton > Link: http://lkml.kernel.org/n/tip-kq6a00qe33h7c7ais2xsywnh@git.kernel.org > Signed-off-by: Ingo Molnar > > commit bd2753b2dda7bb43c7468826de75f49c6a7e8965 > Author: Yinghai Lu > Date: Wed Jun 6 10:55:40 2012 -0700 > > x86/mm: Only add extra pages count for the first memory range during pre-allocatio > > Robin found this regression: > > | I just tried to boot an 8TB system. It fails very early in boot with: > | Kernel panic - not syncing: Cannot find space for the kernel page tables > > git bisect commit 722bc6b16771ed80871e1fd81c86d3627dda2ac8. > > A git revert of that commit does boot past that point on the 8TB > configuration. > > That commit will add up extra pages for all memory range even > above 4g. > > Try to limit that extra page count adding to first entry only. > > Bisected-by: Robin Holt > Tested-by: Robin Holt > Signed-off-by: Yinghai Lu > Cc: WANG Cong > Cc: Linus Torvalds > Cc: Andrew Morton > Cc: Peter Zijlstra > Link: http://lkml.kernel.org/r/CAE9FiQUj3wyzQxtq9yzBNc9u220p8JZ1FYHG7t%3DMOzJ%3D9B > Signed-off-by: Ingo Molnar > > > Signed-off-by: Dave Young > --- > arch/x86/mm/init.c | 22 +++++++++------------- > 1 file changed, 9 insertions(+), 13 deletions(-) The patch looks good. I reproduced the issue with last upstream commit 43c422eda99b894f18d1cca17bcd2401efaf7bd0 and confirmed that it does work with the patch applied. thanks a lot! Acked-by: Flavio Leitner Tested-by: Flavio Leitner fbl -- 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/