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

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Message-ID: <20250703060656.54345-8-aboorvad@linux.ibm.com>
Date: Thu,  3 Jul 2025 11:36:56 +0530
From: Aboorva Devarajan <aboorvad@...ux.ibm.com>
To: akpm@...ux-foundation.org, Liam.Howlett@...cle.com,
        lorenzo.stoakes@...cle.com, shuah@...nel.org, pfalcato@...e.de,
        david@...hat.com, ziy@...dia.com, baolin.wang@...ux.alibaba.com,
        npache@...hat.com, ryan.roberts@....com, dev.jain@....com,
        baohua@...nel.org
Cc: linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org, donettom@...ux.ibm.com,
        ritesh.list@...il.com, aboorvad@...ux.ibm.com
Subject: [PATCH v2 7/7] selftests/mm: Skip hugepage-mremap test if userfaultfd unavailable

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@...ux.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