Re: [PATCH] lib/test_crash: test module to trigger kernel crashes

[Andrew Morton]

On Wed, 27 May 2026 09:56:44 -0700 Calvin Owens <calvin@xxxxxxxxxx> wrote:

> This test calls panic() from various execution contexts in the kernel,
> so the user can see if a crash trace is successfully emitted.
> 
> This is useful for testing console drivers, and can help rule out issues
> with the console itself when silent reboots or hangs are observed on a
> particular system.

Well you aren't the first to write a patch which crashes the kernel ;)

> ---
> I shared this upthread in [1] where it turned out to be useful for
> netconsole. Petr suggested it might be useful for others, so I've
> applied his feedback and cleaned everything up a bit more too.
> 
> It's a superset of what 'echo c > /proc/sysrq-trigger' does, but
> extending that interface doesn't seem practical.

Please fully expand on this?

> The write() implementation requries the entire string be written in a
> single syscall: this is pretty common for these debugfs interfaces, so
> it didn't seem worth the complexity to handle partial writes. But I'm
> happy to do so if somebody cares :)

Some of the above is useful background and deserves to be above the ---
separator.

I'm not really liking the "crash" name.  We already have one of those -
a kexec crashdumping thing.  Maybe "force_panic" or someting.


>  lib/Kconfig.debug |  18 +++++
>  lib/Makefile      |   1 +
>  lib/test_crash.c  | 176 ++++++++++++++++++++++++++++++++++++++++++++++

Some Documentation would be nice.

> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1385,6 +1385,24 @@ config TEST_LOCKUP
>  
>  	  If unsure, say N.
>  
> +config TEST_CRASH
> +	tristate "Test module to trigger crashes"

Some debugfs dependency needed?

> +	help
> +	  Expose a file in debugfs which triggers a panic() call in
> +	  various kernel execution contexts.
> +
> +	      $ cat /sys/kernel/debug/test_crash
> +	      irq
> +	      [...]
> +	      $ echo "irq" > /sys/kernel/debug/test_crash
> +	      Kernel panic - not syncing: User triggered crash in context irq
> +
> +	  This is useful for testing console drivers, and can help rule
> +	  out issues with the console itself when silent reboots or
> +	  hangs are observed on a particular system.
> +
> +	  If unsure, say N.
> +
>  endmenu # "Debug lockups and hangs"
>  
>  menu "Scheduler Debugging"
>
> ...
>