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powerpc/perf: Fix kfree memory allocated for nest pmus

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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: 73ce9aec65 ("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>
This commit is contained in:
Anju T Sudhakar 2017-12-07 22:53:27 +05:30 committed by Michael Ellerman
parent ad2b6e0102
commit 110df8bd3e
1 changed files with 3 additions and 1 deletions
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4
arch/powerpc/perf/imc-pmu.c
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@ -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;
}
}