(bisected) Lock up on sh73a0/kzm9g on cpuidle initialization

[Geert Uytterhoeven]

Hi Daniel,

On Thu, Nov 6, 2014 at 10:02 PM, Daniel Lezcano
<daniel.lezcano at linaro.org> wrote:
> On 11/06/2014 09:38 PM, Geert Uytterhoeven wrote:
>> When CONFIG_CPU_IDLE=y, the kernel locks up during cpuidle initialization
>> on Renesas sh73a0/kzm9g-reference, which has a dual-core Cortex-A9.
>>
>> Last message is:
>>
>>      DMA: preallocated 256 KiB pool for atomic coherent allocations
>>
>> After this it's supposed to print:
>>
>>      cpuidle: using governor ladder
>>      cpuidle: using governor menu
>>
>> I've bisected this to commit 442bf3aaf55a91ebfec71da46a4ee10a3c905bcc
>> ("sched: Let the scheduler see CPU idle states").
>>
>> Reverting that commit, and commit 83a0a96a5f26d974580fd7251043ff70c8f1823d
>> ("sched/fair: Leverage the idle state info when choosing the "idlest"
>> cpu") which
>> depends on it, fixes the problem.
>>
>> I saw the discussion "lockdep splat in CPU hotplug", so I enabled lockdep
>> debugging, but didn't see a lockdep splat.
>
> Did you try the fix attached ?
>
> https://lkml.org/lkml/2014/10/22/722

Thanks, I didn't try that.

However, this patch seems to be in v3.18-rc3, so I'm already using it.
Hence it doesn't fix the problem for me.

On another board, with a dual Cortex-A15, the problem doesn't show up.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds