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

[Zi Yan]

On 19 Mar 2026, at 12:06, Chunyu Hu wrote:

> 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@xxxxxxxxxx>
> Signed-off-by: Chunyu Hu <chuhu@xxxxxxxxxx>
> ---
> 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(+)
>

Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>

Best Regards,
Yan, Zi