Re: [PATCH 6.18.y] mm/damon/tests/core-kunit: catch test failure in test_merge_regions_of()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Typo in the early exit condition causes the unit test to silently skip validation on successful execution.
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commit 8cca227124d565ed51f4791e649f908f0754a67f
Author: SJ Park <sj@kernel.org>

mm/damon/tests/core-kunit: catch test failure in test_merge_regions_of()

This commit adds an early exit to the damon_test_merge_regions_of() unit test
to catch when the region merge expectation is not met. By skipping the
per-region test loop on failure, it prevents potential NULL pointer
dereferences.

Link: https://lore.kernel.org/20260715031002.108504-3-sj@kernel.org
Link: https://lore.kernel.org/20260710144937.26981-1-sj@kernel.org [1]

> diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
> index 6687778752728..c1f0be6746abd 100644
> --- a/mm/damon/tests/core-kunit.h
> +++ b/mm/damon/tests/core-kunit.h
> @@ -264,11 +264,14 @@ static void damon_test_merge_regions_of(struct kunit *test)
>  	damon_merge_regions_of(t, 9, 9999);
>  	/* 0-112, 114-130, 130-156, 156-170 */
>  	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 5u);
> +	if (damon_nr_regions(t) != 6)
> +		goto out;

[Severity: Medium]
Should this check compare against 5 instead of 6?

When damon_merge_regions_of() works correctly, it merges the target into
exactly 5 regions, matching the KUNIT_EXPECT_EQ check immediately above. 

Because 5 != 6 evaluates to true, a successful test execution will jump out 
and silently bypass the per-region validation loop. The validations will only 
execute if exactly 6 regions are produced, which would indicate a test failure.

>  	for (i = 0; i < 5; i++) {
>  		r = __nth_region_of(t, i);
>  		KUNIT_EXPECT_EQ(test, r->ar.start, saddrs[i]);
>  		KUNIT_EXPECT_EQ(test, r->ar.end, eaddrs[i]);
>  	}
> +out:
>  	damon_free_target(t);
>  }

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Sashiko AI review · https://sashiko.dev/#/patchset/20260909033832.132107-1-sj@kernel.org?part=1