Re: [patch 7/7] stacktrace filtering for fault-injection capabilities

Andrew Morton
2006-10-12T21:20:19Z

On Thu, 12 Oct 2006 16:43:12 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:

> From: Akinobu Mita <akinobu.mita@gmail.com>
>
> This patch provides stacktrace filtering feature.
> The stacktrace filter allows failing only for the caller you are
> interested in.
>
> stacktrace filter is enabled by setting the value of
> /debugfs/*/stacktrace-depth more than 0.
> and specify the range of the virtual address
> by the /debugfs/*/address-start and /debugfs/*/address-end
>
> Please see the example that demostrates how to inject slab allocation
> failures only for a specific module
> in Documentation/fault-injection/fault-injection.txt

I read the documentation but I still don't understand this feature. What
does the stacktrace actually do? It gets stored somewhere and displayed
later? What's it all for?

> --- work-fault-inject.orig/lib/Kconfig.debug
> +++ work-fault-inject/lib/Kconfig.debug
> @@ -472,6 +472,8 @@ config LKDTM
>
> config FAULT_INJECTION
> bool
> + select STACKTRACE
> + select FRAME_POINTER
>
> config FAILSLAB
> bool "fault-injection capabilitiy for kmalloc"
>

Is the selection of FRAME_POINTER really needed? The fancy new unwinder
is supposed to be able to handle frame-pointerless unwinding?