Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting

From: Kurt Kanzenbach
Date: Thu Jul 30 2020 - 03:24:06 EST


Hi Vladimir,

On Wed Jul 29 2020, Vladimir Oltean wrote:
> For more context, here is my original report of the issue:
> https://lkml.org/lkml/2020/6/4/1062
>
> Just like you, I could not reproduce the RCU stalls and system hang on a
> 5.6-rt kernel, just on mainline and derivatives, using the plain
> defconfig.
>
> The issue is not specific to Layerscape or i.MX8, but rather I was able
> to see the same behavior on Marvell Armada 37xx as well as Qualcomm
> MSM8976.
>
> So, while of course I agree that disabling IRQ time accounting for arm64
> isn't a real solution, it isn't by far an exaggerated proposal either.
> Nonetheless, the patch is just a RFC and should be treated as such. We
> are at a loss when it comes to debugging this any further and we would
> appreciate some pointers.

Yeah, sure. I'll try to reproduce this issue first. So it triggers with:

* arm64
* mainline, not -rt kernel
* opened serial console
* irq accounting enabled

Anything else?

Thanks,
Kurt

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