[PATCH v4 1/5] selftests/mm/guard-regions: skip collapse test when thp not enabled

[Chunyu Hu <chuhu@redhat.com>]

When thp is not available, just skip the collape tests to avoid the false
negative.

Without the change, run with a thp disabled kernel:
  ./run_vmtests.sh -t madv_guard -n 1
  <snip/>
  #  RUN           guard_regions.anon.collapse ...
  # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
  # collapse: Test terminated by assertion
  #          FAIL  guard_regions.anon.collapse
  not ok 2 guard_regions.anon.collapse
  <snip/>
  #  RUN           guard_regions.shmem.collapse ...
  # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
  # collapse: Test terminated by assertion
  #          FAIL  guard_regions.shmem.collapse
  not ok 32 guard_regions.shmem.collapse
  <snip/>
  #  RUN           guard_regions.file.collapse ...
  # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
  # collapse: Test terminated by assertion
  #          FAIL  guard_regions.file.collapse
  not ok 62 guard_regions.file.collapse
  <snip/>
  # FAILED: 87 / 90 tests passed.
  # 17 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
  # Totals: pass:70 fail:3 xfail:0 xpass:0 skip:17 error:0

With this change, run with thp disabled kernel:
  ./run_vmtests.sh -t madv_guard -n 1
  <snip/>
  #  RUN           guard_regions.anon.collapse ...
  #      SKIP      Transparent Hugepages not available
  #            OK  guard_regions.anon.collapse
  ok 2 guard_regions.anon.collapse # SKIP Transparent Hugepages not available
  <snip/>
  #  RUN           guard_regions.file.collapse ...
  #      SKIP      Transparent Hugepages not available
  #            OK  guard_regions.file.collapse
  ok 62 guard_regions.file.collapse # SKIP Transparent Hugepages not available
  <snip/>
  #  RUN           guard_regions.shmem.collapse ...
  #      SKIP      Transparent Hugepages not available
  #            OK  guard_regions.shmem.collapse
  ok 32 guard_regions.shmem.collapse # SKIP Transparent Hugepages not available
  <snip/>
  # PASSED: 90 / 90 tests passed.
  # 20 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
  # Totals: pass:70 fail:0 xfail:0 xpass:0 skip:20 error:0

CC: Li Wang <liwang@redhat.com>
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
---
Changes in v4:
  - use thp_available instead of thp_is_enabled() as when thp is set to
    never, madvise(MADV_COLLAPSE) will still succeed by design. So a
    failure in madvise(MADV_COLLAPSE) on guard region will verify guard
    region denies it. This is suggested from AI.
  - removed the 'Reviewed-by' and 'Acked-by' as the code changes. Sorry for
    that but it seems the changes is a little huge? (1 out of 2 lines)..
Changes in v3:
  - commit message: update the log snippet with where the fail happens and
    add the '-n1' to the command.
  - fix the 'false positive' to 'false negative'
  - add reviwed by from Mike
Changes in v2:
  - add reviewed by from Zi and Lorenzo
  - add acked-by from David
---
 tools/testing/selftests/mm/guard-regions.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
index dbd21d66d383..48e8b1539be3 100644
--- a/tools/testing/selftests/mm/guard-regions.c
+++ b/tools/testing/selftests/mm/guard-regions.c
@@ -21,6 +21,7 @@
 #include <sys/uio.h>
 #include <unistd.h>
 #include "vm_util.h"
+#include "thp_settings.h"
 
 #include "../pidfd/pidfd.h"
 
@@ -2195,6 +2196,9 @@ TEST_F(guard_regions, collapse)
 	char *ptr;
 	int i;
 
+	if (!thp_available())
+		SKIP(return, "Transparent Hugepages not available\n");
+
 	/* Need file to be correct size for tests for non-anon. */
 	if (variant->backing != ANON_BACKED)
 		ASSERT_EQ(ftruncate(self->fd, size), 0);

base-commit: 8a30aeb0d1b4e4aaf7f7bae72f20f2ae75385ccb
-- 
2.53.0