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SubjectRe: printk NMI splat on boot
On Tue, May 20, 2025 at 02:41:40PM -0600, Jens Axboe wrote:
> On 5/20/25 2:18 PM, Jens Axboe wrote:
> >> What values are you using for CONFIG_RCU_EXP_CPU_STALL_TIMEOUT and
> >> CONFIG_RCU_CPU_STALL_TIMEOUT?
> >
> > CONFIG_RCU_CPU_STALL_TIMEOUT=21
> > CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=2
>
> This was =20 btw, guess it could cut a bit too much...

Just confirming that setting CONFIG_RCU_EXP_CPU_STALL_TIMEOUT to two
milliseconds is more than a bit on the aggressive side. ;-)

Setting it to 20 milliseconds is OK for smartphone-class devices, but
to the best of my knowledge, setting it less than 21 seconds (as in
21,000 milliseconds) has not been tested on any other platform.

> Changed them to:
>
> CONFIG_RCU_CPU_STALL_TIMEOUT=100
> CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=0
>
> and complaining is gone.

This makes it take the default, which in this case would be the specified
CONFIG_RCU_CPU_STALL_TIMEOUT value of 100 seconds. Which is an unusually
long timeout -- mainline these days is 21 seconds and some distros still
use the old value of 60 seconds.

Thanx, Paul

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