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 <a...@linux.vnet.ibm.com>
---
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
