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kworker with empty task->cpus_allowed (was Re: [v4.12-rc1 regression] mount ext4 fs results in kernel crash on PPC64le host)

Message ID 8760fdrdq1.fsf@concordia.ellerman.id.au (mailing list archive)
State Not Applicable
Headers show

Commit Message

Michael Ellerman June 30, 2017, 10:07 a.m. UTC 
Eryu Guan <eguan@redhat.com> writes:
>
> I have to update the patch a bit to make it compile.

Sure.

>> +	WARN_ON(cpumask_empty(worker->task->cpus_allowed));
>> +	WARN_ON(cpumask_empty(pool->attrs->cpumask));
>
> Seems only the last two WARN_ON were triggered.

OK thanks.

Can you try this patch and see if it changes anything? (with the debug
still applied).

We've been trying to reproduce the bug here but haven't had any luck so far.

cheers

Comments

Eryu Guan June 30, 2017, 11:47 a.m. UTC | #1 
On Fri, Jun 30, 2017 at 08:07:02PM +1000, Michael Ellerman wrote:
> Eryu Guan <eguan@redhat.com> writes:
> >
> > I have to update the patch a bit to make it compile.
> 
> Sure.
> 
> >> +	WARN_ON(cpumask_empty(worker->task->cpus_allowed));
> >> +	WARN_ON(cpumask_empty(pool->attrs->cpumask));
> >
> > Seems only the last two WARN_ON were triggered.
> 
> OK thanks.
> 
> Can you try this patch and see if it changes anything? (with the debug
> still applied).

This patch fixes the crash for me. After appliying this patch (with all
other debug patches still applied), kernel didn't print any warnings or
calltraces or debug messages.

> 
> We've been trying to reproduce the bug here but haven't had any luck so far.

I'm using this reproducer:
for i in `seq 5`; do
	mkfs -t ext4 -F /dev/sda5 && sleep 3 && mount /dev/sda5 /mnt/ext4 && umount /dev/sda5
done

Thanks,
Eryu

> 
> cheers
> 
> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index 4640f6d64f8b..b310ecc07e00 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -733,6 +733,8 @@ void __init setup_per_cpu_areas(void)
>  	for_each_possible_cpu(cpu) {
>                  __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
>  		paca[cpu].data_offset = __per_cpu_offset[cpu];
> +
> +		set_cpu_numa_node(cpu, numa_cpu_lookup_table[cpu]);
>  	}
>  }
>  #endif
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Patch

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 4640f6d64f8b..b310ecc07e00 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -733,6 +733,8 @@  void __init setup_per_cpu_areas(void)
 	for_each_possible_cpu(cpu) {
                 __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
 		paca[cpu].data_offset = __per_cpu_offset[cpu];
+
+		set_cpu_numa_node(cpu, numa_cpu_lookup_table[cpu]);
 	}
 }
 #endif