Re: [PATCH v2 5/7] selftests/mm: Fix child process exit codes in ksm_functional_tests

[David Hildenbrand]

On 03.07.25 08:06, Aboorva Devarajan wrote:
> In ksm_functional_tests, test_child_ksm() returned negative values
> to indicate errors. However, when passed to exit(), these were
> interpreted as large unsigned values (e.g, -2 became 254), leading to
> incorrect handling in the parent process. As a result, some tests
> appeared to be skipped or silently failed.
>
> This patch changes test_child_ksm() to return positive error codes
> (1, 2, 3) and updates test_child_ksm_err() to interpret them correctly.
> This ensures the parent accurately detects and reports child process
> failures.
>
> --------------
> Before patch:
> --------------
> - [RUN] test_unmerge
> ok 1 Pages were unmerged
> ...
> - [RUN] test_prctl_fork
> - No pages got merged
> - [RUN] test_prctl_fork_exec
> ok 7 PR_SET_MEMORY_MERGE value is inherited
> ...
> Bail out! 1 out of 8 tests failed
> - Planned tests != run tests (9 != 8)
> - Totals: pass:7 fail:1 xfail:0 xpass:0 skip:0 error:0
>
> --------------
> After patch:
> --------------
> - [RUN] test_unmerge
> ok 1 Pages were unmerged
> ...
> - [RUN] test_prctl_fork
> - No pages got merged
> not ok 7 Merge in child failed
> - [RUN] test_prctl_fork_exec
> ok 8 PR_SET_MEMORY_MERGE value is inherited
> ...
> Bail out! 2 out of 9 tests failed
> - Totals: pass:7 fail:2 xfail:0 xpass:0 skip:0 error:0
>
> Fixes: 6c47de3be3a0 ("selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec")
> Signed-off-by: Aboorva Devarajan <aboorvad@xxxxxxxxxxxxx>

Surprising, but seems to be the right thing to do.

Acked-by: David Hildenbrand <david@xxxxxxxxxx>

--
Cheers,

David / dhildenb