[Intel-gfx] [PATCH] drm/i915/selftests: fixup igt_shrink_thp

[Matthew Auld]

On 06/09/2021 13:19, Tvrtko Ursulin wrote:
> 
> On 06/09/2021 10:17, Matthew Auld wrote:
>> Since the object might still be active here, the shrink_all will simply
>> ignore it, which blows up in the test, since the pages will still be
>> there. Currently THP is disabled which should result in the test being
>> skipped, but if we ever re-enable THP we might start seeing the failure.
>> Fix this by forcing I915_SHRINK_ACTIVE.
>>
>> v2: Some machine in the shard runs doesn't seem to have any available
>> swap when running this test. Try to handle this.
>>
>> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
>> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com> #v1
>> ---
>>   .../gpu/drm/i915/gem/selftests/huge_pages.c   | 31 ++++++++++++++-----
>>   1 file changed, 24 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c 
>> b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> index a094f3ce1a90..46ea1997c114 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> @@ -1519,6 +1519,7 @@ static int igt_shrink_thp(void *arg)
>>       struct i915_vma *vma;
>>       unsigned int flags = PIN_USER;
>>       unsigned int n;
>> +    bool should_swap;
>>       int err = 0;
>>       /*
>> @@ -1567,23 +1568,39 @@ static int igt_shrink_thp(void *arg)
>>               break;
>>       }
>>       i915_gem_context_unlock_engines(ctx);
>> +    /*
>> +     * Nuke everything *before* we unpin the pages so we can be 
>> reasonably
>> +     * sure that when later checking get_nr_swap_pages() that some 
>> random
>> +     * leftover object doesn't steal the remaining swap space.
>> +     */
>> +    i915_gem_shrink(NULL, i915, -1UL, NULL,
>> +            I915_SHRINK_BOUND |
>> +            I915_SHRINK_UNBOUND |
>> +            I915_SHRINK_ACTIVE);
>>       i915_vma_unpin(vma);
>>       if (err)
>>           goto out_put;
>> +
>>       /*
>> -     * Now that the pages are *unpinned* shrink-all should invoke
>> -     * shmem to truncate our pages.
>> +     * Now that the pages are *unpinned* shrinking should invoke
>> +     * shmem to truncate our pages, if we have available swap.
>>        */
>> -    i915_gem_shrink_all(i915);
>> -    if (i915_gem_object_has_pages(obj)) {
>> -        pr_err("shrink-all didn't truncate the pages\n");
>> +    should_swap = get_nr_swap_pages() > 0;
>> +    i915_gem_shrink(NULL, i915, -1UL, NULL,
>> +            I915_SHRINK_BOUND |
>> +            I915_SHRINK_UNBOUND |
>> +            I915_SHRINK_ACTIVE);
>> +    if (should_swap == i915_gem_object_has_pages(obj)) {
> 
> Hmm is there any value running the test if no swap (given objects used 
> by the test are "willneed"), or you could simplify and just do early skip?

Maybe. My thinking was that this adds some coverage if say the device is 
not configured with swap. i.e assert that the pages don't magically 
disappear, and that their contents still persist etc.

Happy to make it skip instead though?

> 
> Regards,
> 
> Tvrtko
> 
>> +        pr_err("unexpected pages mismatch, should_swap=%s\n",
>> +               yesno(should_swap));
>>           err = -EINVAL;
>>           goto out_put;
>>       }
>> -    if (obj->mm.page_sizes.sg || obj->mm.page_sizes.phys) {
>> -        pr_err("residual page-size bits left\n");
>> +    if (should_swap == (obj->mm.page_sizes.sg || 
>> obj->mm.page_sizes.phys)) {
>> +        pr_err("unexpected residual page-size bits, should_swap=%s\n",
>> +               yesno(should_swap));
>>           err = -EINVAL;
>>           goto out_put;
>>       }
>>