Re: [Xen-devel] [PATCH v2 09/10] xen/arm: Free memory allocated for sibling/core maps on CPU hot-unplug

[Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>]

Thanks Julien, I fixed this

On Mon, Apr 23, 2018 at 1:38 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> Hi,
>
>
> On 20/04/18 13:25, Mirela Simonovic wrote:
>>
>> The memory allocated in setup_cpu_sibling_map() when a CPU is hotplugged
>> has to be freed when the CPU is hot-unplugged. This is done in
>> remove_cpu_sibling_map() and called from __cpu_disable() on CPU
>> hot-unplug.
>>
>> Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
>>
>> ---
>> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> CC: Julien Grall <julien.grall@xxxxxxx>
>> ---
>>   xen/arch/arm/smpboot.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
>> index b4ed479dc6..d01b51592d 100644
>> --- a/xen/arch/arm/smpboot.c
>> +++ b/xen/arch/arm/smpboot.c
>> @@ -89,6 +89,12 @@ static void setup_cpu_sibling_map(int cpu)
>>       cpumask_set_cpu(cpu, per_cpu(cpu_core_mask, cpu));
>>   }
>>   +static void remove_cpu_sibling_map(int cpu)
>> +{
>> +    free_cpumask_var(per_cpu(cpu_sibling_mask, cpu));
>> +    free_cpumask_var(per_cpu(cpu_core_mask, cpu));
>> +}
>> +
>>   void __init
>>   smp_clear_cpu_maps (void)
>>   {
>> @@ -391,6 +397,8 @@ void __cpu_disable(void)
>>       /* It's now safe to remove this processor from the online map */
>>       cpumask_clear_cpu(cpu, &cpu_online_map);
>>   +    remove_cpu_sibling_map(cpu);
>
>
> I don't think this is the right place. Those cpumask might be used by the
> scheduler. So you want to free them only when the scheduler has been
> disabled.
>
> Looking at x86, they will free them when the CPU is completely dead (see
> cpu_smpboot_callback). So I think a notifier would be the solution for arm
> as well.
>
> Cheers,
>
>
>> +
>>       if ( cpu_disable_scheduler(cpu) )
>>           BUG();
>>       smp_mb();
>>
>
> --
> Julien Grall

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