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[PATCH v2 7/7] selftests/mm: Skip hugepage-mremap test if userfaultfd unavailable

Aboorva Devarajan posted 7 patches 3 months ago
There is a newer version of this series
[PATCH v2 7/7] selftests/mm: Skip hugepage-mremap test if userfaultfd unavailable
Posted by Aboorva Devarajan 3 months ago 
Gracefully skip test if userfaultfd is not supported (ENOSYS) or not
permitted (EPERM), instead of failing. This avoids misleading failures
with clear skip messages.
--------------
Before Patch
--------------
~ running ./hugepage-mremap
...
~ Bail out! userfaultfd: Function not implemented
~ Planned tests != run tests (1 != 0)
~ Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
~ [FAIL]
not ok 4 hugepage-mremap # exit=1

--------------
After Patch
--------------
~ running ./hugepage-mremap
...
~ ok 2 # SKIP userfaultfd is not supported/not enabled.
~ 1 skipped test(s) detected.
~ Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0
~ [SKIP]
ok 4 hugepage-mremap # SKIP

Signed-off-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
---
 tools/testing/selftests/mm/hugepage-mremap.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
index c463d1c09c9b..1a0e6dd87578 100644
--- a/tools/testing/selftests/mm/hugepage-mremap.c
+++ b/tools/testing/selftests/mm/hugepage-mremap.c
@@ -65,10 +65,20 @@ static void register_region_with_uffd(char *addr, size_t len)
 	struct uffdio_api uffdio_api;
 
 	/* Create and enable userfaultfd object. */
-
 	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
-	if (uffd == -1)
-		ksft_exit_fail_msg("userfaultfd: %s\n", strerror(errno));
+	if (uffd == -1) {
+		switch (errno) {
+		case EPERM:
+			ksft_exit_skip("No userfaultfd permissions, try running as root.\n");
+			break;
+		case ENOSYS:
+			ksft_exit_skip("userfaultfd is not supported/not enabled.\n");
+			break;
+		default:
+			ksft_exit_fail_msg("userfaultfd failed with %s\n", strerror(errno));
+			break;
+		}
+	}
 
 	uffdio_api.api = UFFD_API;
 	uffdio_api.features = 0;
-- 
2.43.5
Re: [PATCH v2 7/7] selftests/mm: Skip hugepage-mremap test if userfaultfd unavailable
Posted by David Hildenbrand 3 months ago 
On 03.07.25 08:06, Aboorva Devarajan wrote:
> Gracefully skip test if userfaultfd is not supported (ENOSYS) or not
> permitted (EPERM), instead of failing. This avoids misleading failures
> with clear skip messages.
> --------------
> Before Patch
> --------------
> ~ running ./hugepage-mremap
> ...
> ~ Bail out! userfaultfd: Function not implemented
> ~ Planned tests != run tests (1 != 0)
> ~ Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
> ~ [FAIL]
> not ok 4 hugepage-mremap # exit=1
> 
> --------------
> After Patch
> --------------
> ~ running ./hugepage-mremap
> ...
> ~ ok 2 # SKIP userfaultfd is not supported/not enabled.
> ~ 1 skipped test(s) detected.
> ~ Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0
> ~ [SKIP]
> ok 4 hugepage-mremap # SKIP
> 
> Signed-off-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
> ---
>   tools/testing/selftests/mm/hugepage-mremap.c | 16 +++++++++++++---
>   1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
> index c463d1c09c9b..1a0e6dd87578 100644
> --- a/tools/testing/selftests/mm/hugepage-mremap.c
> +++ b/tools/testing/selftests/mm/hugepage-mremap.c
> @@ -65,10 +65,20 @@ static void register_region_with_uffd(char *addr, size_t len)
>   	struct uffdio_api uffdio_api;
>   
>   	/* Create and enable userfaultfd object. */
> -
>   	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
> -	if (uffd == -1)
> -		ksft_exit_fail_msg("userfaultfd: %s\n", strerror(errno));
> +	if (uffd == -1) {
> +		switch (errno) {
> +		case EPERM:
> +			ksft_exit_skip("No userfaultfd permissions, try running as root.\n");

"Insufficient permissions, try ..." ?

> +			break;
> +		case ENOSYS:
> +			ksft_exit_skip("userfaultfd is not supported/not enabled.\n");
> +			break;

Note that we have in tools/testing/selftests/mm/config

	CONFIG_USERFAULTFD=y

But I don't have anything about making the test more versatile.

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb
Re: [PATCH v2 7/7] selftests/mm: Skip hugepage-mremap test if userfaultfd unavailable
Posted by Zi Yan 3 months ago 
On 3 Jul 2025, at 4:38, David Hildenbrand wrote:

> On 03.07.25 08:06, Aboorva Devarajan wrote:
>> Gracefully skip test if userfaultfd is not supported (ENOSYS) or not
>> permitted (EPERM), instead of failing. This avoids misleading failures
>> with clear skip messages.
>> --------------
>> Before Patch
>> --------------
>> ~ running ./hugepage-mremap
>> ...
>> ~ Bail out! userfaultfd: Function not implemented
>> ~ Planned tests != run tests (1 != 0)
>> ~ Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
>> ~ [FAIL]
>> not ok 4 hugepage-mremap # exit=1
>>
>> --------------
>> After Patch
>> --------------
>> ~ running ./hugepage-mremap
>> ...
>> ~ ok 2 # SKIP userfaultfd is not supported/not enabled.
>> ~ 1 skipped test(s) detected.
>> ~ Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0
>> ~ [SKIP]
>> ok 4 hugepage-mremap # SKIP
>>
>> Signed-off-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
>> ---
>>   tools/testing/selftests/mm/hugepage-mremap.c | 16 +++++++++++++---
>>   1 file changed, 13 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
>> index c463d1c09c9b..1a0e6dd87578 100644
>> --- a/tools/testing/selftests/mm/hugepage-mremap.c
>> +++ b/tools/testing/selftests/mm/hugepage-mremap.c
>> @@ -65,10 +65,20 @@ static void register_region_with_uffd(char *addr, size_t len)
>>   	struct uffdio_api uffdio_api;
>>    	/* Create and enable userfaultfd object. */
>> -
>>   	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
>> -	if (uffd == -1)
>> -		ksft_exit_fail_msg("userfaultfd: %s\n", strerror(errno));
>> +	if (uffd == -1) {
>> +		switch (errno) {
>> +		case EPERM:
>> +			ksft_exit_skip("No userfaultfd permissions, try running as root.\n");
>
> "Insufficient permissions, try ..." ?
>
>> +			break;
>> +		case ENOSYS:
>> +			ksft_exit_skip("userfaultfd is not supported/not enabled.\n");
>> +			break;
>
> Note that we have in tools/testing/selftests/mm/config
>
> 	CONFIG_USERFAULTFD=y

I added the same fix to guard-regions.c since I did not know the config
file existed.

And from git history, I learnt that I could use the command below to merge
these config to my local config:
“./scripts/kconfig/merge_config.sh .config tools/testing/selftests/xxx/config”

Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

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