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Subject: Re: 5.6-rc3: WARNING: CPU: 48 PID: 17435 at kernel/sched/fair.c:380
 enqueue_task_fair+0x328/0x440
To:     Christian Borntraeger <borntraeger@de.ibm.com>,
        Vincent Guittot <vincent.guittot@linaro.org>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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From:   Dietmar Eggemann <dietmar.eggemann@arm.com>
Message-ID: <ef1be100-2c6a-bcff-69a2-25878589a111@arm.com>
Date:   Thu, 5 Mar 2020 13:12:39 +0100
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On 05/03/2020 12:28, Christian Borntraeger wrote:
> 
> On 05.03.20 10:30, Vincent Guittot wrote:
>> Le mercredi 04 mars 2020 à 20:59:33 (+0100), Christian Borntraeger a écrit :
>>>
>>> On 04.03.20 20:38, Christian Borntraeger wrote:
>>>>
>>>>
>>>> On 04.03.20 20:19, Dietmar Eggemann wrote:

[...]

> It seems to speed up the issue when I do a compile job in parallel on the host:
> 
> Do you also need the sysfs tree?

[   87.932552] CPU23 path=/machine.slice/machine-test.slice/machine-qemu\x2d18\x2dtest10. on_list=1 nr_running=1 throttled=0 p=[CPU 2/KVM 2662]
[   87.932559] CPU23 path=/machine.slice/machine-test.slice/machine-qemu\x2d18\x2dtest10. on_list=0 nr_running=3 throttled=0 p=[CPU 2/KVM 2662]
[   87.932562] CPU23 path=/machine.slice/machine-test.slice on_list=1 nr_running=1 throttled=1 p=[CPU 2/KVM 2662]
[   87.932564] CPU23 path=/machine.slice on_list=1 nr_running=0 throttled=0 p=[CPU 2/KVM 2662]
[   87.932566] CPU23 path=/ on_list=1 nr_running=1 throttled=0 p=[CPU 2/KVM 2662]
[   87.951872] CPU23 path=/ on_list=1 nr_running=2 throttled=0 p=[ksoftirqd/23 126]
[   87.987528] CPU23 path=/user.slice on_list=1 nr_running=2 throttled=0 p=[as 6737]
[   87.987533] CPU23 path=/ on_list=1 nr_running=1 throttled=0 p=[as 6737]

Arrh, looks like 'char path[64]' is too small to hold 'machine.slice/machine-test.slice/machine-qemu\x2d18\x2dtest10.scope/vcpuX' !
                                                                                                                    ^  
But I guess that the 'on_list=0' for 'machine-qemu\x2d18\x2dtest10.scope' could be the missing hint?