From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752315Ab0CYWbk (ORCPT ); Thu, 25 Mar 2010 18:31:40 -0400 Received: from rcsinet11.oracle.com ([148.87.113.123]:21006 "EHLO rcsinet11.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750760Ab0CYWbi (ORCPT ); Thu, 25 Mar 2010 18:31:38 -0400 Date: Thu, 25 Mar 2010 15:29:00 -0700 From: Joel Becker To: Yinghai Lu Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andrew Morton , David Miller , Benjamin Herrenschmidt , Linus Torvalds , linux-kernel@vger.kernel.org, Ian Campbell , Peter Zijlstra Subject: Re: [PATCH 1/8] x86: do not free zero sized per cpu areas Message-ID: <20100325222859.GC9984@mail.oracle.com> Mail-Followup-To: Yinghai Lu , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andrew Morton , David Miller , Benjamin Herrenschmidt , Linus Torvalds , linux-kernel@vger.kernel.org, Ian Campbell , Peter Zijlstra References: <1269427029-21000-1-git-send-email-yinghai@kernel.org> <1269427029-21000-2-git-send-email-yinghai@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1269427029-21000-2-git-send-email-yinghai@kernel.org> X-Burt-Line: Trees are cool. X-Red-Smith: Ninety feet between bases is perhaps as close as man has ever come to perfection. User-Agent: Mutt/1.5.20 (2009-06-14) X-Source-IP: acsmt354.oracle.com [141.146.40.154] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090205.4BABE3DF.00BF:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 24, 2010 at 03:37:02AM -0700, Yinghai Lu wrote: > From: Ian Campbell > > This avoids an infinite loop in free_early_partial(). > > Add a warning to free_early_partial to catch future problems. > > -v5: put back start > end back into WARN_ONCE() > -v6: use one line for if according to linus > > Signed-off-by: Ian Campbell > Signed-off-by: Yinghai Lu > Cc: Peter Zijlstra > Cc: Ingo Molnar Tested-by: Joel Becker I ran into this when moving my paravirt_ops PVMs to 2.6.34-rc1. I turned on CONFIG_NO_BOOTMEM to try it because it was the default. I had to put earlyprintk=xen on the command line to debug the problem. My boots hung after: ... (early) Local APIC disabled by BIOS -- you can enable it with "lapic" (early) APIC: disable apic facility (early) APIC: switched to apic NOOP (early) Allocating PCI resources starting at 78000000 (gap: 78000000:88000000) (early) Booting paravirtualized kernel on Xen (early) Xen version: 3.1.3-rc3 (early) setup_percpu: NR_CPUS:8 nr_cpumask_bits:8 nr_cpu_ids:2 nr_node_ids:1 Bisecting narrowed the problem to fb90ef [early_res: Add free_early_partial()]. Turning off CONFIG_NO_BOOTMEM allowed me to boot. I then hunted up references to this function, which found me this patch. This patch successfully resolved the problem. Joel -- "The nice thing about egotists is that they don't talk about other people." - Lucille S. Harper Joel Becker Principal Software Developer Oracle E-mail: joel.becker@oracle.com Phone: (650) 506-8127