Re: [RFC PATCH v2 02/17] mm/damon/paddr: support PGIDLE_UNSET probe filter type

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The newly introduced DAMON_FILTER_TYPE_PGIDLE_UNSET probe filter type is completely inaccessible from userspace because it was omitted from the sysfs string mappings.
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--- Patch [2]: [RFC PATCH v2 02/17] mm/damon/paddr: support PGIDLE_UNSET probe filter type ---
commit 28cc087ac53ca1eb5ea0ff45e8fd4a6108a12c9f
Author: SJ Park <sj@kernel.org>

mm/damon/paddr: support PGIDLE_UNSET probe filter type

Implement support of DAMON_FILTER_TYPE_PGIDLE_UNSET in the physical
address space DAMON operations set. It reuses damon_folio_young(),
which was being used for access monitoring.

> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> index 5a6a78054784a..199de1463fa06 100644
> --- a/mm/damon/paddr.c
> +++ b/mm/damon/paddr.c
> @@ -132,6 +132,12 @@ static bool damon_pa_filter_match(struct damon_filter *filter,
>  			matched = filter->memcg_id == mem_cgroup_id(memcg);
>  		rcu_read_unlock();
>  		break;
> +	case DAMON_FILTER_TYPE_PGIDLE_UNSET:

[Severity: Medium]
Will this new filter type be inaccessible from userspace?

The DAMON_FILTER_TYPE_PGIDLE_UNSET filter type appears to be missing from the
damon_sysfs_filter_type_names array in mm/damon/sysfs.c:

static const struct damon_sysfs_filter_type_name
damon_sysfs_filter_type_names[] = {
	{
		.type = DAMON_FILTER_TYPE_ANON,
		.name = "anon",
	},
	{
		.type = DAMON_FILTER_TYPE_MEMCG,
		.name = "memcg",
	},
};

Without adding it here (for example, as "pgidle_unset"), won't userspace
attempts to configure this filter via sysfs be rejected with -EINVAL,
effectively making it unusable?

> +		if (!folio)
> +			matched = false;
> +		else
> +			matched = damon_folio_young(folio);
> +		break;
>  	default:
>  		break;
>  	}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260726173935.94046-1-sj@kernel.org?part=2