Re: hmm_test issues with latest mainline

[Shuah Khan <skhan@linuxfoundation.org>]

On 10/13/22 11:12, Vlastimil Babka wrote:
> On 10/13/22 19:10, Shuah Khan wrote:
>> On 10/13/22 11:01, David Hildenbrand wrote:
>>> On 13.10.22 18:54, 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:
>>>>
>>>> --- a/tools/testing/selftests/vm/hmm-tests.c
>>>> +++ b/tools/testing/selftests/vm/hmm-tests.c
>>>> @@ -154,6 +154,11 @@ FIXTURE_TEARDOWN(hmm)
>>>>    {
>>>>        int ret = close(self->fd);
>>>> +    if (ret != 0) {
>>>> +        fprintf(stderr, "close returned (%d) fd is (%d)\n", ret,self->fd);
>>>> +        exit(1);
>>>> +    }
>>>> +
>>>>        ASSERT_EQ(ret, 0);
>>>>        self->fd = -1;
>>>>    }
>>>>
>>>> Next, there are some tests that fail (and thus also trigger the issue above)
>>>>
>>>> #  RUN           hmm.hmm_device_private.exclusive ...
>>>> # hmm-tests.c:1702:exclusive:Expected ret (-16) == 0 (0)
>>>> close returned (-1) fd is (3)
>>>> # exclusive: Test failed at step #1
>>>> #          FAIL  hmm.hmm_device_private.exclusive
>>>> not ok 20 hmm.hmm_device_private.exclusive
>>>> #  RUN           hmm.hmm_device_private.exclusive_mprotect ...
>>>> # hmm-tests.c:1756:exclusive_mprotect:Expected ret (-16) == 0 (0)
>>>> close returned (-1) fd is (3)
>>>> # exclusive_mprotect: Test failed at step #1
>>>> #          FAIL  hmm.hmm_device_private.exclusive_mprotect
>>>> not ok 21 hmm.hmm_device_private.exclusive_mprotect
>>>> #  RUN           hmm.hmm_device_private.exclusive_cow ...
>>>> # hmm-tests.c:1809:exclusive_cow:Expected ret (-16) == 0 (0)
>>>> close returned (-1) fd is (3)
>>>> # exclusive_cow: Test failed at step #1
>>>> #          FAIL  hmm.hmm_device_private.exclusive_cow
>>>> not ok 22 hmm.hmm_device_private.exclusive_cow
>>>>
>>>>
>>>
>>> When did that test start failing? Was it still ok for 6.0?
> 
> Didn't test yet, will try, in case it's my system/config specific thing.
> 
>>>
>>
>> commit 4fe89d07dcc2804c8b562f6c7896a45643d34b2f (tag: v6.0, linux/master)
>>
>> # FAILED: 25 / 50 tests passed.
>> # Totals: pass:25 fail:25 xfail:0 xpass:0 skip:0 error:0
>>
>> Looks good to me.
> 
> Hmm but there's 25 that failed? Or are those also misreported SKIPs?
> 

Likely the case. Here is an observation. All of these FAILs are coming
from line 141 which is FIXTURE_SETUP. See the result:

# hmm-tests.c:141:open_close:Expected self->fd (-1) >= 0 (0)
# open_close: Test terminated by assertion
#          FAIL  hmm.hmm_device_private.open_close
not ok 1 hmm.hmm_device_private.open_close

However the code is:

FIXTURE_SETUP(hmm)
{
         self->page_size = sysconf(_SC_PAGE_SIZE);
         self->page_shift = ffs(self->page_size) - 1;

         self->fd = hmm_open(variant->device_number);
         if (self->fd < 0 && hmm_is_coherent_type(variant->device_number))
                 SKIP(exit(0), "DEVICE_COHERENT not available");

Note: It is SKIP(). It appears it will be reported as fail unless both of
the above conditions are true. Perhaps this check should be either of these
conditions is true, it is skip.

         ASSERT_GE(self->fd, 0);
}


Looks like this test could a review to see if all these conditions should
be a FAIL or SKIP. This problem exists in 6.0.

thanks,
-- Shuah