Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751738AbdIUBqt (ORCPT ); Wed, 20 Sep 2017 21:46:49 -0400 Received: from ozlabs.org ([103.22.144.67]:49985 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751390AbdIUBqp (ORCPT ); Wed, 20 Sep 2017 21:46:45 -0400 X-powerpc-patch-notification: thanks X-powerpc-patch-commit: 4917fcb58cc73f6b81455e3c5f960144809ddf1a In-Reply-To: <1505801826-12396-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com> To: Ravi Bangoria , linuxppc-dev@lists.ozlabs.org From: Michael Ellerman Cc: maddy@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, Ravi Bangoria , paulus@samba.org, kan.liang@intel.com, tglx@linutronix.de, mingo@kernel.org Subject: Re: powerpc/sysrq: Fix oops whem ppmu is not registered Message-Id: <3xyKGX1f9lz9sRV@ozlabs.org> Date: Thu, 21 Sep 2017 11:46:43 +1000 (AEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 929 Lines: 27 On Tue, 2017-09-19 at 06:17:06 UTC, Ravi Bangoria wrote: > Kernel crashes if power pmu is not registered and user tries to dump > regs with 'echo p > /proc/sysrq-trigger'. Sample log: > > Unable to handle kernel paging request for data at address 0x00000008 > Faulting instruction address: 0xc0000000000d52f0 > > NIP [c0000000000d52f0] perf_event_print_debug+0x10/0x230 > LR [c00000000058a938] sysrq_handle_showregs+0x38/0x50 > Call Trace: > printk+0x38/0x4c (unreliable) > __handle_sysrq+0xe4/0x270 > write_sysrq_trigger+0x64/0x80 > proc_reg_write+0x80/0xd0 > __vfs_write+0x40/0x200 > vfs_write+0xc8/0x240 > SyS_write+0x60/0x110 > system_call+0x58/0x6c > > Signed-off-by: Ravi Bangoria > Reviewed-by: Kamalesh Babulal Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/4917fcb58cc73f6b81455e3c5f9601 cheers