From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 3yt2Q35fcWzDsNH for ; Fri, 8 Dec 2017 04:23:39 +1100 (AEDT) Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vB7HJH5a122003 for ; Thu, 7 Dec 2017 12:23:36 -0500 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 2eq82uxy6g-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 07 Dec 2017 12:23:36 -0500 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 7 Dec 2017 17:23:34 -0000 From: Anju T Sudhakar To: mpe@ellerman.id.au Cc: linuxppc-dev@lists.ozlabs.org, maddy@linux.vnet.ibm.com, anju@linux.vnet.ibm.com Subject: [PATCH] powerpc/perf: Fix kfree memory allocated for nest pmus Date: Thu, 7 Dec 2017 22:53:27 +0530 Message-Id: <1512667407-30067-1-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: , imc_common_cpuhp_mem_free() is the common function for all IMC (In-memory Collection counters) domains to unregister cpuhotplug callback and free memory. Since kfree of memory allocated for nest-imc (per_nest_pmu_arr) is in the common code, all domains (core/nest/thread) can do the kfree in the failure case. This could potentially create a call trace as shown below, where core(/thread/nest) imc pmu initialization fails and in the failure path imc_common_cpuhp_mem_free() free the memory(per_nest_pmu_arr), which is allocated by successfully registered nest units. The call trace is generated in a scenario where core-imc initialization is made to fail and a cpuhotplug is performed in a p9 system. During cpuhotplug ppc_nest_imc_cpu_offline() tries to access per_nest_pmu_arr, which is already freed by core-imc. [ 136.563618] NIP [c000000000cb6a94] mutex_lock+0x34/0x90 [ 136.563653] LR [c000000000cb6a88] mutex_lock+0x28/0x90 [ 136.563687] Call Trace: [ 136.563707] [c0000016b7a93b90] [c000000000cb6a88] mutex_lock+0x28/0x90 (unreliable) [ 136.563762] [c0000016b7a93bc0] [c0000000002bc720] perf_pmu_migrate_context+0x90/0x3a0 [ 136.563814] [c0000016b7a93c60] [c0000000000f7a40] ppc_nest_imc_cpu_offline+0x190/0x1f0 [ 136.563867] [c0000016b7a93cb0] [c000000000108140] cpuhp_invoke_callback+0x160/0x820 [ 136.563918] [c0000016b7a93d30] [c00000000010939c] cpuhp_thread_fun+0x1bc/0x270 [ 136.563970] [c0000016b7a93d60] [c00000000013d2b0] smpboot_thread_fn+0x250/0x290 [ 136.564022] [c0000016b7a93dc0] [c000000000136f18] kthread+0x1a8/0x1b0 [ 136.564067] [c0000016b7a93e30] [c00000000000b4e8] ret_from_kernel_thread+0x5c/0x74 To address this scenario do the kfree(per_nest_pmu_arr) only in case of nest-imc initialization failure, and when there is no other nest units registered. Fixes: 73ce9aec65b1 ("powerpc/perf: Fix IMC_MAX_PMU macro") Signed-off-by: Anju T Sudhakar --- arch/powerpc/perf/imc-pmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c index 0ead3cd..4eb9e2b 100644 --- a/arch/powerpc/perf/imc-pmu.c +++ b/arch/powerpc/perf/imc-pmu.c @@ -1171,6 +1171,7 @@ static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr) if (nest_pmus == 1) { cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE); kfree(nest_imc_refc); + kfree(per_nest_pmu_arr); } if (nest_pmus > 0) @@ -1195,7 +1196,6 @@ static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr) kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]->attrs); kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]); kfree(pmu_ptr); - kfree(per_nest_pmu_arr); return; } @@ -1309,6 +1309,8 @@ int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_id ret = nest_pmu_cpumask_init(); if (ret) { mutex_unlock(&nest_init_lock); + kfree(nest_imc_refc); + kfree(per_nest_pmu_arr); goto err_free; } } -- 2.7.4