Re: [PATCH v3 7/7] kunit: Add tests for fault

[Guenter Roeck]

On 4/22/24 06:08, Mickaël Salaün wrote:
> On Fri, Apr 19, 2024 at 04:38:01PM -0700, Guenter Roeck wrote:
> > On Fri, Apr 19, 2024 at 03:33:49PM -0700, Guenter Roeck wrote:
> > > Hi,
> > >
> > > On Tue, Mar 19, 2024 at 11:48:57AM +0100, Mickaël Salaün wrote:
> > > > Add a test case to check NULL pointer dereference and make sure it would
> > > > result as a failed test.
> > > >
> > > > The full kunit_fault test suite is marked as skipped when run on UML
> > > > because it would result to a kernel panic.
> > > >
> > > > Tested with:
> > > > ./tools/testing/kunit/kunit.py run --arch x86_64 kunit_fault
> > > > ./tools/testing/kunit/kunit.py run --arch arm64 \
> > > >    --cross_compile=aarch64-linux-gnu- kunit_fault
> > >
> > > What is the rationale for adding those tests unconditionally whenever
> > > CONFIG_KUNIT_TEST is enabled ? This completely messes up my test system
> > > because it concludes that it is pointless to continue testing
> > > after the "Unable to handle kernel NULL pointer dereference" backtrace.
> > > At the same time, it is all or nothing, meaning I can not disable
> > > it but still run other kunit tests.
>
> CONFIG_KUNIT_TEST is to test KUnit itself.  Why does this messes up your
> test system, and what is your test system?  Is it related to the kernel
> warning and then the message you previously sent?

It is not a warning, it is a BUG which terminates the affected kernel thread.
NULL pointer dereferences are normally fatal, which is why I abort tests
if one is encountered. I am not going to start introducing code into my
scripts to ignore such warnings (or BUG messages) on a case by case basis;
this would be unmaintainable.

> https://lore.kernel.org/r/fd604ae0-5630-4745-acf2-1e51c69cf0c0@xxxxxxxxxxxx
> It seems David has a solution to suppress such warning.

I don't think so. My series tried to suppress warning backtraces, not BUG
messages. BUG messages can not easily be suppressed since the reaction is
architecture specific and typically fatal.

As I said below, never mind, I just disabled CONFIG_KUNIT_TEST in my testing.

Guenter

> > Oh, never mind. I just disabled CONFIG_KUNIT_TEST in my test bed
> > to "solve" the problem. I'll take that as one of those "unintended
> > consequences" items: Instead of more tests, there are fewer.
> >
> > Guenter