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Some systems (e.g. minimal or real-time kernels) may not enable Transparent Hugepages (THP), causing MADV_HUGEPAGE to return EINVAL. This patch introduces a runtime check using the existing THP sysfs interface and skips the hugepage merging test (`-H`) when THP is not available. To avoid those failures: # ----------------------------- # running ./ksm_tests -H -s 100 # ----------------------------- # ksm_tests: MADV_HUGEPAGE: Invalid argument # [FAIL] not ok 1 ksm_tests -H -s 100 # exit=2 # -------------------- # running ./khugepaged # -------------------- # Reading PMD pagesize failed# [FAIL] not ok 1 khugepaged # exit=1 # -------------------- # running ./soft-dirty # -------------------- # TAP version 13 # 1..15 # ok 1 Test test_simple # ok 2 Test test_vma_reuse dirty bit of allocated page # ok 3 Test test_vma_reuse dirty bit of reused address page # Bail out! Reading PMD pagesize failed# Planned tests != run tests (15 != 3) # # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0 # [FAIL] not ok 1 soft-dirty # exit=1 # SUMMARY: PASS=0 SKIP=0 FAIL=1 # ------------------- # running ./migration # ------------------- # TAP version 13 # 1..3 # # Starting 3 tests from 1 test cases. # # RUN migration.private_anon ... # # OK migration.private_anon # ok 1 migration.private_anon # # RUN migration.shared_anon ... # # OK migration.shared_anon # ok 2 migration.shared_anon # # RUN migration.private_anon_thp ... # # migration.c:196:private_anon_thp:Expected madvise(ptr, TWOMEG, MADV_HUGEPAGE) (-1) == 0 (0) # # private_anon_thp: Test terminated by assertion # # FAIL migration.private_anon_thp # not ok 3 migration.private_anon_thp # # FAILED: 2 / 3 tests passed. # # Totals: pass:2 fail:1 xfail:0 xpass:0 skip:0 error:0 # [FAIL] not ok 1 migration # exit=1 It's true that CONFIG_TRANSPARENT_HUGEPAGE=y is explicitly enabled in tools/testing/selftests/mm/config, so ideally the runtime environment should also support THP. However, in practice, we've found that on some systems: - THP is disabled at boot time (transparent_hugepage=never) - Or manually disabled via sysfs - Or unavailable in RT kernels, containers, or minimal CI environments In these cases, the test will fail with EINVAL on madvise(MADV_HUGEPAGE), even though the kernel config is correct. To make the test suite more robust and avoid false negatives, this patch adds a runtime check for /sys/kernel/mm/transparent_hugepage/enabled. If THP is not available, the hugepage test (-H) is skipped with a clear message. Link: https://lkml.kernel.org/r/20250624032748.393836-1-liwang@redhat.com Signed-off-by: Li Wang <liwang@redhat.com> Cc: Aruna Ramakrishna <aruna.ramakrishna@oracle.com> Cc: Bagas Sanjaya <bagasdotme@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Joey Gouly <joey.gouly@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Keith Lucas <keith.lucas@oracle.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>