how to hard hang the kernel from userspace?

[valdis.kletnieks at vt.edu]

On Wed, 06 Dec 2017 16:32:26 -0800, Daniel Walker said:

> and it works sometimes on UP, but it doesn't work on SMP. I also tried

Thinking about *why* that hangs a UP should explain why it doesn't work
on SMP.

> adding in "taskset" to pin multiple version of the "yes" command to each
> cpu in the system, but that just resulted in lots of rcu warnings.

That's.... unexpected.

> The goal is to make the watchdog trigger by starving out the watchdog
> petting process. Anyone have any ideas? I'd rather not make a kernel module.

What are you trying to achieve by doing that?

Have you tried just pointing a 'kill -9' at the watchdog monitor process?  Are you using
in-kernel watchdogd, or one in userspace?
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