forked from Minki/linux
110df8bd3e
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:
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||
|---|---|---|
| .. | ||
| boot | ||
| configs | ||
| crypto | ||
| include | ||
| kernel | ||
| kvm | ||
| lib | ||
| math-emu | ||
| mm | ||
| net | ||
| oprofile | ||
| perf | ||
| platforms | ||
| purgatory | ||
| sysdev | ||
| tools | ||
| xmon | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||
| Makefile.postlink | ||