Re: [RFC PATCH v2.1 3/7] mm/damon/core: support probe_hits_wsum damos core filter

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Low] Missing kunit test coverage for the newly added DAMOS_FILTER_TYPE_PROBE_HITS_WSUM filter.
- [Low] The kerneldoc for `enum damos_filter_type` was not updated to reflect that `DAMOS_FILTER_TYPE_PROBE_HITS_WSUM` is a core layer filter.
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commit 3af974fc20158a639272fd766ad727c8d30c0f3e
Author: SJ Park <sj@kernel.org>

mm/damon/core: support probe_hits_wsum damos core filter

Implement probe_hits_wsum DAMOS core filter support in the core layer.
Make three small changes for the support: update damos_filter_for_ops() to
treat probe_hits_wsum filter as core filter, update destination
damos_filter->range_{min,max} for probe_hits_wsum, and extend
damos_filter_match() to handle the new filter type.

> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index e9630f41e51fe..d9d56f4be1a97 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -658,6 +658,7 @@ bool damos_filter_for_ops(enum damos_filter_type type)
>  	switch (type) {
>  	case DAMOS_FILTER_TYPE_ADDR:
>  	case DAMOS_FILTER_TYPE_TARGET:
> +	case DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:

[Severity: Low]
Does the kerneldoc for enum damos_filter_type need to be updated to reflect
that DAMOS_FILTER_TYPE_PROBE_HITS_WSUM is a core layer filter?

include/linux/damon.h:enum damos_filter_type {
 * All types except &DAMOS_FILTER_TYPE_ADDR and &DAMOS_FILTER_TYPE_TARGET
 * are handled by the underlying &struct damon_operations as a part of scheme
 * action trying, and therefore accounted as 'tried'.

The documentation here explicitly lists only ADDR and TARGET as exceptions,
failing to update the list with the newly added PROBE_HITS_WSUM core filter.

>  		return false;
>  	default:
>  		break;

[ ... ]

> @@ -1332,6 +1333,10 @@ static void damos_commit_filter_arg(
>  	case DAMOS_FILTER_TYPE_HUGEPAGE_SIZE:
>  		dst->sz_range = src->sz_range;
>  		break;
> +	case DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:
> +		dst->range_min = src->range_min;
> +		dst->range_max = src->range_max;
> +		break;

[Severity: Low]
Is there missing KUnit test coverage for the newly added
DAMOS_FILTER_TYPE_PROBE_HITS_WSUM filter?

The copying logic for the new filter type's arguments (range_min, range_max)
is left untested, which could hide future regressions.

In mm/damon/tests/core-kunit.h:damos_test_commit_filter_for(), the switch
statement verifies filter argument copying but is missing the case for
DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:

	case DAMOS_FILTER_TYPE_HUGEPAGE_SIZE:
		KUNIT_EXPECT_EQ(test, dst->sz_range.min, src->sz_range.min);
		KUNIT_EXPECT_EQ(test, dst->sz_range.max, src->sz_range.max);
		break;
	default:
		break;
	}

Additionally, in mm/damon/tests/core-kunit.h:damos_test_commit_filter(),
the function enumerates all filter types for testing but fails to include
instances of DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:

	damos_test_commit_filter_for(test, &dst,
			&(struct damos_filter){
			.type = DAMOS_FILTER_TYPE_TARGET,
			.matching = true,
			.allow = true,
			.target_idx = 6,
			});

>  	default:
>  		break;
>  	}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260910040319.147037-1-sj@kernel.org?part=3