Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755890Ab3C2HWT (ORCPT ); Fri, 29 Mar 2013 03:22:19 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:44877 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754379Ab3C2HWR (ORCPT ); Fri, 29 Mar 2013 03:22:17 -0400 Message-ID: <5155413E.6090002@oracle.com> Date: Fri, 29 Mar 2013 15:22:38 +0800 From: Zhenzhong Duan Reply-To: zhenzhong.duan@oracle.com Organization: oracle User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20130307 Thunderbird/17.0.4 MIME-Version: 1.0 To: "linux-kernel@vger.kernel.org" CC: Konrad Rzeszutek Wilk , Feng Jin , Tamon Shiose Subject: [PATCH] xen: Don't call arch_trigger_all_cpu_backtrace in dom0(pvm) Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1893 Lines: 49 nmi isn't supported in dom0, fallback to general all cpu backtrace code. Without fix, on xapic system, sysrq+l, no backtrace is showed. On x2apic enabled system, got NULL pointer dereference as below. SysRq : Show backtrace of all active CPUs BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] memcpy+0xb/0x120 Call Trace: [] ? __x2apic_send_IPI_mask+0x73/0x160 [] x2apic_send_IPI_all+0x1e/0x20 [] arch_trigger_all_cpu_backtrace+0x6c/0xb0 [] ? _raw_spin_lock_irqsave+0x34/0x50 [] sysrq_handle_showallcpus+0xe/0x10 [] __handle_sysrq+0x7d/0x140 [] ? __handle_sysrq+0x140/0x140 [] write_sysrq_trigger+0x57/0x60 [] proc_reg_write+0x86/0xc0 [] vfs_write+0xce/0x190 [] sys_write+0x55/0x90 [] system_call_fastpath+0x16/0x1b Signed-off-by: Zhenzhong Duan Tested-by: Tamon Shiose --- include/linux/nmi.h | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/include/linux/nmi.h b/include/linux/nmi.h index db50840..b845757 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -32,6 +32,8 @@ static inline void touch_nmi_watchdog(void) #ifdef arch_trigger_all_cpu_backtrace static inline bool trigger_all_cpu_backtrace(void) { + if (xen_domain()) + return false; arch_trigger_all_cpu_backtrace(); return true; -- 1.7.3 -- 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/