From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3yCxyH6sR8zDqlv for ; Fri, 13 Oct 2017 17:04:54 +1100 (AEDT) Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v9D643vt096126 for ; Fri, 13 Oct 2017 02:04:52 -0400 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0a-001b2d01.pphosted.com with ESMTP id 2djg967j49-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 13 Oct 2017 02:04:51 -0400 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 13 Oct 2017 06:59:49 +0100 Received: from d23av06.au.ibm.com (d23av06.au.ibm.com [9.190.235.151]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v9D5xjGT25886862 for ; Fri, 13 Oct 2017 05:59:46 GMT Received: from d23av06.au.ibm.com (localhost [127.0.0.1]) by d23av06.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v9D5xilp032064 for ; Fri, 13 Oct 2017 16:59:44 +1100 From: Anju T Sudhakar To: mpe@ellerman.id.au Cc: maddy@linux.vnet.ibm.com, anju@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH V2] powerpc/perf: Fix IMC initialization crash Date: Fri, 13 Oct 2017 11:29:41 +0530 Message-Id: <1507874381-11264-1-git-send-email-anju@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Call trace observed with latest firmware, and upstream kernel. [ 14.499938] NIP [c0000000000f318c] init_imc_pmu+0x8c/0xcf0 [ 14.499973] LR [c0000000000f33f8] init_imc_pmu+0x2f8/0xcf0 [ 14.500007] Call Trace: [ 14.500027] [c000003fed18f710] [c0000000000f33c8] init_imc_pmu+0x2c8/0xcf0 (unreliable) [ 14.500080] [c000003fed18f800] [c0000000000b5ec0] opal_imc_counters_probe+0x300/0x400 [ 14.500132] [c000003fed18f900] [c000000000807ef4] platform_drv_probe+0x64/0x110 [ 14.500185] [c000003fed18f980] [c000000000804b58] driver_probe_device+0x3d8/0x580 [ 14.500236] [c000003fed18fa10] [c000000000804e4c] __driver_attach+0x14c/0x1a0 [ 14.500302] [c000003fed18fa90] [c00000000080156c] bus_for_each_dev+0x8c/0xf0 [ 14.500353] [c000003fed18fae0] [c000000000803fa4] driver_attach+0x34/0x50 [ 14.500397] [c000003fed18fb00] [c000000000803688] bus_add_driver+0x298/0x350 [ 14.500449] [c000003fed18fb90] [c00000000080605c] driver_register+0x9c/0x180 [ 14.500500] [c000003fed18fc00] [c000000000807dec] __platform_driver_register+0x5c/0x70 [ 14.500552] [c000003fed18fc20] [c00000000101cee0] opal_imc_driver_init+0x2c/0x40 [ 14.500603] [c000003fed18fc40] [c00000000000d084] do_one_initcall+0x64/0x1d0 [ 14.500654] [c000003fed18fd00] [c00000000100434c] kernel_init_freeable+0x280/0x374 [ 14.500705] [c000003fed18fdc0] [c00000000000d314] kernel_init+0x24/0x160 [ 14.500750] [c000003fed18fe30] [c00000000000b4e8] ret_from_kernel_thread+0x5c/0x74 [ 14.500799] Instruction dump: [ 14.500827] 4082024c 2f890002 419e054c 2e890003 41960094 2e890001 3ba0ffea 419602d8 [ 14.500884] 419e0290 2f890003 419e02a8 e93e0118 2fa30000 419e0010 4827ba41 [ 14.500945] ---[ end trace 27b734ad26f1add4 ]--- [ 15.908719] [ 16.908869] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007 [ 16.908869] [ 18.125813] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007] While registering nest imc at init, cpu-hotplug callback `nest_pmu_cpumask_init()` makes an opal call to stop the engine. And if the OPAL call fails, imc_common_cpuhp_mem_free() is invoked to cleanup memory and cpuhotplug setup. But when cleaning up the attribute group, we were dereferencing the attribute element array without checking whether the backing element is not NULL. This causes the kernel panic. Add a check for the backing element prior to dereferencing the attribute element, to handle the failing case gracefully. Signed-off-by: Anju T Sudhakar Reported-by: Pridhiviraj Paidipeddi --- arch/powerpc/perf/imc-pmu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c index 9ccac86f3463..001504b0e800 100644 --- a/arch/powerpc/perf/imc-pmu.c +++ b/arch/powerpc/perf/imc-pmu.c @@ -1148,7 +1148,8 @@ static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr) } /* Only free the attr_groups which are dynamically allocated */ - kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]->attrs); + if (pmu_ptr->attr_groups[IMC_EVENT_ATTR]) + kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]->attrs); kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]); kfree(pmu_ptr); return; -- 2.14.1