Re: [PATCH 1/2] selftests/mm: skip uffd tests in madv_guard if uffd is not present.

[Zi Yan <ziy@nvidia.com>]

On 15 May 2025, at 14:41, Lorenzo Stoakes wrote:

> Ah you got to this first :) thanks!
>
> Could you do this with a cover letter though? It's really weird to have 2/2
> reply to 1/2, I know sometimes people do that, but it's just odd, and it'd be
> good to have an overview, thanks!
>
> On Thu, May 15, 2025 at 02:23:32PM -0400, Zi Yan wrote:
>> When userfaultfd is not compiled into kernel, userfaultfd() returns -1,
>> causing uffd tests in madv_guard fail. Skip the tests instead.
>
> 'madv_guard'? I'd just say the guard_regions.uffd test to fail.

Sure. Will change it.
>
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>>  tools/testing/selftests/mm/guard-regions.c | 17 +++++++++++++++--
>>  1 file changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
>> index 0cd9d236649d..93af3d3760f9 100644
>> --- a/tools/testing/selftests/mm/guard-regions.c
>> +++ b/tools/testing/selftests/mm/guard-regions.c
>> @@ -1453,8 +1453,21 @@ TEST_F(guard_regions, uffd)
>>
>>  	/* Set up uffd. */
>>  	uffd = userfaultfd(0);
>> -	if (uffd == -1 && errno == EPERM)
>> -		ksft_exit_skip("No userfaultfd permissions, try running as root.\n");
>
> Let's just make this all part of the same switch please!

What do you mean? EPERM is handled in the switch-case below.

>
> And while I originally used ksft_exit_skip(), I think we can just use the
> SKIP(return, ...) form here just fine to keep it consistent.

Right. I am using SKIP below, since when I ran it, ksft_exit_skip()
makes the whole test message inconsistent.

>
>> +	if (uffd == -1) {
>> +		switch (errno) {
>> +		case EPERM:
>> +			SKIP(return, "No userfaultfd permissions, try running as root.");
>> +			break;
>> +		case ENOSYS:
>> +			SKIP(return, "userfaultfd is not supported/not enabled.");
>> +			break;
>> +		default:
>> +			ksft_exit_fail_msg("userfaultfd failed with %s\n",
>> +					   strerror(errno));
>> +			break;
>> +		}
>> +	}
>> +
>>  	ASSERT_NE(uffd, -1);
>>
>>  	ASSERT_EQ(ioctl(uffd, UFFDIO_API, &api), 0);
>> --
>> 2.47.2
>>
>
> Thanks!


--
Best Regards,
Yan, Zi