On Mon, Aug 03, 2020 at 10:04:01AM +0200, Kurt Kanzenbach wrote:
On Thu Jul 30 2020, Vladimir Oltean wrote:
On Thu, Jul 30, 2020 at 09:23:44AM +0200, Kurt Kanzenbach wrote:
On Wed Jul 29 2020, Vladimir Oltean wrote:
For more context, here is my original report of the issue:
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
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
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:
* mainline, not -rt kernel
* opened serial console
* irq accounting enabled
Thanks for giving a helping hand, Kurt. The defconfig should be enough.
In the interest of full disclosure, the only arm64 device on which we
didn't reproduce this was the 16-core LX2160A. But we did reproduce on
that with maxcpus=1 though. And also on msm8976 with all 8 cores booted.
Just mentioning this in case you're testing on a 16-core system, you
might want to reduce the number a bit.
OK. I've reproduced it on a Marvell Armada SoC with v5.6 mainline. See
splats below. Running with irq time accounting enabled, kills the
machine immediately. However, I'm not getting the possible deadlock
warnings in 8250 as you did. So that might be unrelated.
Yes, the console lockdep warnings are unrelated. They are discussed
Unfortunately I have no idea what to debug here.
So, this means we could submit a formal version of this patch? :)