Re: [Patch v8 01/23] perf/x86/intel: Validate return value of intel_pmu_init_hybrid()

[Mi, Dapeng]

On 5/29/2026 7:11 PM, Peter Zijlstra wrote:
> On Fri, May 29, 2026 at 03:56:23PM +0800, Dapeng Mi wrote:
>> The memory allocation for the x86_pmu.hybrid_pmu[] array in
>> intel_pmu_init_hybrid() can theoretically fail due to memory shortages.
>> If this occurs, the initialization of the x86 hybrid PMU would fail.
>>
>> Currently, the code does not check the return value of the
>> intel_pmu_init_hybrid() function, which could lead to attempts to access
>> the uninitialized x86_pmu.hybrid_pmu[] array, potentially causing a
>> system panic.
>>
>> So, adds a check for the return value of intel_pmu_init_hybrid() to
>> prevent invalid memory access in such scenarios.
>>
>> Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
>> ---
>>
>> V8: New patch.
>>
>>  arch/x86/events/intel/core.c | 29 ++++++++++++++++++++++-------
>>  1 file changed, 22 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
>> index 0217e701aeeb..85c329bd52be 100644
>> --- a/arch/x86/events/intel/core.c
>> +++ b/arch/x86/events/intel/core.c
>> @@ -7870,6 +7870,7 @@ __init int intel_pmu_init(void)
>>  	int version, i;
>>  	char *name;
>>  	struct x86_hybrid_pmu *pmu;
>> +	int ret;
>>  
>>  	/* Architectural Perfmon was introduced starting with Core "Yonah" */
>>  	if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) {
>> @@ -8545,7 +8546,9 @@ __init int intel_pmu_init(void)
>>  		 *
>>  		 * Initialize the common PerfMon capabilities here.
>>  		 */
>> -		intel_pmu_init_hybrid(hybrid_big_small);
>> +		ret = intel_pmu_init_hybrid(hybrid_big_small);
>> +		if (ret < 0)
>> +			return ret;
> Sashiko notes this will leak the intel_pmu_arch_lbt_init() kmemcache.
>
> I'm not entirely sure we care much about that, but its not really nice.

Sashiko did a good job!

Yes, it's a bug and would be fixed in next version. Thanks.