On Wed, 22 Jul 2015, Mike Kravetz wrote:

On 07/22/2015 03:30 PM, Andrew Morton wrote:

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On Wed, 22 Jul 2015 15:19:54 -0700 Davidlohr Bueso [off-list ref] wrote:

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I didn't know that libhugetlbfs has tests.  I wonder if that makes
tools/testing/selftests/vm's hugetlbfstest harmful?

Why harmful? Redundant, maybe(?).

The presence of the in-kernel tests will cause people to add stuff to
them when it would be better if they were to apply that effort to
making libhugetlbfs better.  Or vice versa.

Mike's work is an example.  Someone later makes a change to hugetlbfs, runs
the kernel selftest and says "yay, everything works", unaware that they
just broke fallocate support.

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Does anyone even use selftests for
hugetlbfs regression testing? Lets see, we also have these:

- hugepage-{mmap,shm}.c
- map_hugetlb.c

There's probably a lot of room for improvement here.

selftests is a pretty scrappy place.  It's partly a dumping ground for
things so useful test code doesn't just get lost and bitrotted.  Partly
a framework so people who add features can easily test them. Partly to
provide tools to architecture maintainers when they wire up new
syscalls and the like.

Unless there's some good reason to retain the hugetlb part of
selftests, I'm thinking we should just remove it to avoid
distracting/misleading people.  Or possibly move the libhugetlbfs test
code into the kernel tree and maintain it there.

Adding Eric as he is the libhugetlbfs maintainer.

I think removing the hugetlb selftests in the kernel and pointing
people to libhugetlbfs is the way to go.  From a very quick scan
of the selftests, I would guess libhugetlbfs covers everything
in those tests.

I'm willing to verify the testing provided by selftests is included
in libhugetlbfs, and remove selftests if that is the direction we
want to take.

I would rather see the test suite stay in the library, there are a
number of tests that rely on infrastructure in the library that is not
available in selftests.

I am happy to help with any tests that need to be added/modified in the
library to cover.