Re: [PATCH v4 01/13] cpu: Free cpu->cpu_ases in cpu_address_space_destroy()

[Mark Kanda <mark.kanda@oracle.com>]

On 3/23/2022 1:56 PM, Philippe Mathieu-Daudé wrote:
> On 23/3/22 18:17, Philippe Mathieu-Daudé wrote:
>> From: Mark Kanda <mark.kanda@oracle.com>
>>
>> Create cpu_address_space_destroy() to free a CPU's cpu_ases list.
>
> This seems incorrect...
>
>> vCPU hotunplug related leak reported by Valgrind:
>>
>> ==132362== 216 bytes in 1 blocks are definitely lost in loss record 7,119 of 
>> 8,549
>> ==132362==    at 0x4C3ADBB: calloc (vg_replace_malloc.c:1117)
>> ==132362==    by 0x69EE4CD: g_malloc0 (in /usr/lib64/libglib-2.0.so.0.5600.4)
>> ==132362==    by 0x7E34AF: cpu_address_space_init (physmem.c:751)
>> ==132362==    by 0x45053E: qemu_init_vcpu (cpus.c:635)
>> ==132362==    by 0x76B4A7: x86_cpu_realizefn (cpu.c:6520)
>> ==132362==    by 0x9343ED: device_set_realized (qdev.c:531)
>> ==132362==    by 0x93E26F: property_set_bool (object.c:2273)
>> ==132362==    by 0x93C23E: object_property_set (object.c:1408)
>> ==132362==    by 0x9406DC: object_property_set_qobject (qom-qobject.c:28)
>> ==132362==    by 0x93C5A9: object_property_set_bool (object.c:1477)
>> ==132362==    by 0x933C81: qdev_realize (qdev.c:333)
>> ==132362==    by 0x455E9A: qdev_device_add_from_qdict (qdev-monitor.c:713)
>>
>> Signed-off-by: Mark Kanda <mark.kanda@oracle.com>
>> Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> Message-Id: <20220321141409.3112932-5-mark.kanda@oracle.com>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>   cpu.c                     | 1 +
>>   include/exec/cpu-common.h | 7 +++++++
>>   softmmu/physmem.c         | 5 +++++
>>   3 files changed, 13 insertions(+)
>>
>> diff --git a/cpu.c b/cpu.c
>> index be1f8b074c..59352a1487 100644
>> --- a/cpu.c
>> +++ b/cpu.c
>> @@ -174,6 +174,7 @@ void cpu_exec_unrealizefn(CPUState *cpu)
>>           tcg_exec_unrealizefn(cpu);
>>       }
>>   +    cpu_address_space_destroy(cpu);
>>       cpu_list_remove(cpu);
>>   }
>>   diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
>> index 50a7d2912e..b17ad61ae4 100644
>> --- a/include/exec/cpu-common.h
>> +++ b/include/exec/cpu-common.h
>> @@ -111,6 +111,13 @@ size_t qemu_ram_pagesize_largest(void);
>>    */
>>   void cpu_address_space_init(CPUState *cpu, int asidx,
>>                               const char *prefix, MemoryRegion *mr);
>
> ... cpu_address_space_init() creates a single AS, ...
>
>> +/**
>> + * cpu_address_space_destroy:
>> + * @cpu: CPU for this address space
>> + *
>> + * Cleanup CPU's cpu_ases list.
>> + */
>> +void cpu_address_space_destroy(CPUState *cpu);
>>     void cpu_physical_memory_rw(hwaddr addr, void *buf,
>>                               hwaddr len, bool is_write);
>> diff --git a/softmmu/physmem.c b/softmmu/physmem.c
>> index 43ae70fbe2..aec61ca07a 100644
>> --- a/softmmu/physmem.c
>> +++ b/softmmu/physmem.c
>> @@ -762,6 +762,11 @@ void cpu_address_space_init(CPUState *cpu, int asidx,
>>       }
>>   }
>>   +void cpu_address_space_destroy(CPUState *cpu)
>> +{
>> +    g_free(cpu->cpu_ases);
>
> ... but here you destroy all the ASes.

I was thinking the whole ASes list should be freed because the CPU is going away...

Thanks/regards,
-Mark