Re: [RFC PATCH v1.1 04/14] mm/damon/tests/vaddr-kunit: replace damon_add_region() with damon_set_regions()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Memory leak of the `damon_target` structure and attached regions when `damon_set_regions()` fails.
--

commit e0458a31c6f6c7f46d6a9ef3e90d4098d89686fd
Author: SeongJae Park <sj@kernel.org>

mm/damon/tests/vaddr-kunit: replace damon_add_region() with damon_set_regions()

This commit updates the DAMON virtual address operation set unit tests to
use damon_set_regions() instead of damon_add_region() for region setup. This
aligns the tests with how other DAMON API callers set up regions.

> diff --git a/mm/damon/tests/vaddr-kunit.h b/mm/damon/tests/vaddr-kunit.h
> index 98e734d77d517..de30db9b753e5 100644
> --- a/mm/damon/tests/vaddr-kunit.h
> +++ b/mm/damon/tests/vaddr-kunit.h
> @@ -132,22 +132,32 @@ static void damon_do_test_apply_three_regions(struct kunit *test,
>  				unsigned long *expected, int nr_expected)
>  {
>  	struct damon_target *t;

[ ... ]

>  	t = damon_new_target();
>  	if (!t)
>  		kunit_skip(test, "target alloc fail");
> +
> +	ranges = kmalloc_array(nr_regions / 2, sizeof(*ranges), GFP_KERNEL);
> +	if (!ranges) {
> +		damon_destroy_target(t, NULL);
> +		kunit_skip(test, "ranges alloc fail");
> +	}

[ ... ]

> +	if (damon_set_regions(t, ranges, nr_regions / 2,
> +				DAMON_MIN_REGION_SZ)) {
> +		kfree(ranges);
> +		kunit_skip(test, "damon_set_regions() fail");

[Severity: Medium]
Does this error path leak the damon_target structure and its attached regions?

Unlike the earlier kmalloc_array() error path which calls
damon_destroy_target(t, NULL) before skipping, this failure path seems
to omit the cleanup. Because kunit_skip() aborts test execution via a
long jump, the target allocated via damon_new_target() wouldn't get freed.

>  	}
> +	kfree(ranges);
>  
> -	damon_set_regions(t, three_regions, 3, DAMON_MIN_REGION_SZ);
> +	if (damon_set_regions(t, three_regions, 3, DAMON_MIN_REGION_SZ))
> +		kunit_skip(test, "second damon_set_regions() fail");

[Severity: Medium]
Could the same memory leak occur here? 

If the second damon_set_regions() fails, kunit_skip() is called without
first freeing the target structure.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260521035349.87565-1-sj@kernel.org?part=4