On 01/16/2018 01:59 PM, Thomas Gleixner wrote:
> On Tue, 16 Jan 2018, Yu, Fenghua wrote:
>>> From: Thomas Gleixner [mailto:t...@linutronix.de]
>> Is this a Haswell specific issue?
>>
>> I run the following test forever without issue on Broadwell and 4.15.0-rc6 
>> with rdt mounted:
>> for ((;;)) do
>>         for ((i=1;i<88;i++)) do
>>                 echo 0 >/sys/devices/system/cpu/cpu$i/online
>>         done
>>         echo "online cpus:"
>>         grep processor /proc/cpuinfo |wc
>>         for ((i=1;i<88;i++)) do
>>                 echo 1 >/sys/devices/system/cpu/cpu$i/online
>>         done
>>         echo "online cpus:"
>>         grep processor /proc/cpuinfo|wc
>> done
>>
>> I'm finding a Haswell to reproduce the issue.
> Come on. This is crystal clear from the KASAN trace. And the fix is simple 
> enough.
>
> You simply do not run into it because on your machine
>
>     is_llc_occupancy_enabled() is false...
>
> Thanks,
>
>       tglx
>       
> 8<--------------------        
>
> diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
> index 88dcf8479013..99442370de40 100644
> --- a/arch/x86/kernel/cpu/intel_rdt.c
> +++ b/arch/x86/kernel/cpu/intel_rdt.c
> @@ -525,10 +525,6 @@ static void domain_remove_cpu(int cpu, struct 
> rdt_resource *r)
>                */
>               if (static_branch_unlikely(&rdt_mon_enable_key))
>                       rmdir_mondata_subdir_allrdtgrp(r, d->id);
> -             kfree(d->ctrl_val);
> -             kfree(d->rmid_busy_llc);
> -             kfree(d->mbm_total);
> -             kfree(d->mbm_local);
>               list_del(&d->list);
>               if (is_mbm_enabled())
>                       cancel_delayed_work(&d->mbm_over);
> @@ -545,6 +541,10 @@ static void domain_remove_cpu(int cpu, struct 
> rdt_resource *r)
>                       cancel_delayed_work(&d->cqm_limbo);
>               }
>  
> +             kfree(d->ctrl_val);
> +             kfree(d->rmid_busy_llc);
> +             kfree(d->mbm_total);
> +             kfree(d->mbm_local);
>               kfree(d);
>               return;
>       }

Hi Thomas,

Testing of your patch shows that your patch resolves the bug.  Thanks
for the assistance!  Is this something you could submit to mainline?

Thanks,


Joe

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https://bugs.launchpad.net/bugs/1733662

Title:
  System hang with Linux kernel due to mainline commit 24247aeeabe

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