[PATCH RESEND v1 2/5] selftests/mm: skip guard hole-punch test if MADV_REMOVE is unsupported

[Muhammad Usama Anjum <usama.anjum@arm.com>]

The hole_punch case verifies that guard regions survive MADV_REMOVE and
that the backing range is punched out.  MADV_REMOVE delegates the hole
punch to the backing filesystem, which may reject the operation with
EOPNOTSUPP.

That result means the test cannot establish the state whose guard
semantics it intends to validate.  Treating the missing filesystem
capability as a guard-region failure creates a false regression.

Unmap the range and skip only when MADV_REMOVE fails with EOPNOTSUPP.
Preserve the assertion for all other errors so failures on supported
configurations remain visible.

Signed-off-by: Muhammad Usama Anjum <usama.anjum@arm.com>
---
 tools/testing/selftests/mm/guard-regions.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
index b21df3040b1c7..5c8ec3ca75d7d 100644
--- a/tools/testing/selftests/mm/guard-regions.c
+++ b/tools/testing/selftests/mm/guard-regions.c
@@ -1912,7 +1912,7 @@ TEST_F(guard_regions, hole_punch)
 {
 	const unsigned long page_size = self->page_size;
 	char *ptr;
-	int i;
+	int i, ret;
 
 	if (variant->backing == ANON_BACKED)
 		SKIP(return, "Truncation test specific to file-backed");
@@ -1944,8 +1944,12 @@ TEST_F(guard_regions, hole_punch)
 	}
 
 	/* Now hole punch the guarded region. */
-	ASSERT_EQ(madvise(&ptr[3 * page_size], 4 * page_size,
-			  MADV_REMOVE), 0);
+	ret = madvise(&ptr[3 * page_size], 4 * page_size, MADV_REMOVE);
+	if (ret == -1 && errno == EOPNOTSUPP) {
+		ASSERT_EQ(munmap(ptr, 10 * page_size), 0);
+		SKIP(return, "MADV_REMOVE not supported by filesystem");
+	}
+	ASSERT_EQ(ret, 0);
 
 	/* Ensure guard regions remain. */
 	for (i = 0; i < 10; i++) {
-- 
2.47.3