Re: [PATCH] fault-inject: use a shared initialization helper for the random state

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 12 Nov 2026 23:46:34 +0900 Sang-Heon Jeon <ekffu200098@gmail.com> wrote:

> fault_rnd_state can be seeded from setup_fault_attr(),
> fault_create_debugfs_attr() and fault_config_init(), and each of them
> uses its own guard. Configuring fault injection in more than one way
> leads to useless reseeding.
> 
> To prevent this, use a shared initialization helper fault_random_init()
> in all three places. So fault_rnd_state is seeded only once per boot.

Thanks, that looks nice.


Generally, fault-injection doesn't see to get used very much, and the
huge number of AI-generated you-messed-up-error-handling reports we're
receiving show the cost of that.

syskaller can use it and those people have shown some
interesting/useful results from its use.

I have a side-project going where I get the LLM to drive patch testing
on a local test machine.  The AI looks at the patches, figures out test
plans then controls their execution.  One of the many things I'm
telling it do is to fault-inject every error path which the patchset(s)
add.  It seems to do this quite well.  So I'm a big user of
fault-injection now.

I'm hoping that I can also make it use kcov: use coverage
instrumentation to verify that all code which the patchset added or
altered has been runtime testing.

But oh my, it's soooooooooo slooooooooooooow.  It does really
impressive testing, but I need to make it run 10x faster :(