From 110df8bd3e418b3476cae80babe8add48a8ea523 Mon Sep 17 00:00:00 2001
From: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Date: Thu, 7 Dec 2017 22:53:27 +0530
Subject: [PATCH] powerpc/perf: Fix kfree memory allocated for nest pmus
References: bsc#1054914
Patch-mainline: v4.15-rc5
Git-commit: 110df8bd3e418b3476cae80babe8add48a8ea523
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.
NIP [c000000000cb6a94] mutex_lock+0x34/0x90
LR [c000000000cb6a88] mutex_lock+0x28/0x90
Call Trace:
mutex_lock+0x28/0x90 (unreliable)
perf_pmu_migrate_context+0x90/0x3a0
ppc_nest_imc_cpu_offline+0x190/0x1f0
cpuhp_invoke_callback+0x160/0x820
cpuhp_thread_fun+0x1bc/0x270
smpboot_thread_fn+0x250/0x290
kthread+0x1a8/0x1b0
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 <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
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 f1b940714d65..be4e7f84f70a 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -1184,6 +1184,7 @@ 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)
@@ -1208,7 +1209,6 @@ 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;
}
@@ -1322,6 +1322,8 @@ 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;
}
}
--
2.13.6