Re: hmm_test issues with latest mainline

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Oct 14, 2022 at 11:03:39AM -0400, Felix Kuehling wrote:
> Am 2022-10-14 um 08:01 schrieb Jason Gunthorpe:
> > On Thu, Oct 13, 2022 at 06:54:24PM +0200, Vlastimil Babka wrote:
> > > Hi,
> > > 
> > > I've been trying the hmm_tests as of today's commit:
> > > 
> > > a185a0995518 ("Merge tag 'linux-kselftest-kunit-6.1-rc1-2' ...)
> > > 
> > > and run into several issues that seemed worth reporting.
> > > 
> > > First, it seems the FIXTURE_TEARDOWN(hmm) in
> > > tools/testing/selftests/vm/hmm-tests.c
> > > using ASSERT_EQ(ret, 0); can run into an infinite loop of reporting the
> > > assertion failure. Dunno if it's a kselftests issue or it's a bug to
> > > use asserts in teardown. I hacked it up like this locally to proceed:
> > I've seen this too in other tests, it is a kselftests bug/limitation,
> > AFAIK. You can't use assert macros in those functions.
> 
> I vaguely remember looking at this when I reviewed Alex's patches that added
> device-coherent support. We wanted to have these checks in the fixture setup
> so that we wouldn't have to duplicate them in all the tests.
> 
> I'm not sure if I missed it in review, and Alex missed it in testing, or if
> this is a regression that happened more recently. Sorry for the trouble. It
> looks like Alistair already figured out a fix.

I think the design is fine, it is just surprising you can't call
ASSERT/etc in the fixture codes. Hopefully something like Alistair's
fix gets merged.

Jason