Re: [PATCH 05/17] mm/damon/core: introduce damon_prep struct

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Missing exported cleanup API for `struct damon_prep` leads to broken abstraction on error paths.
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commit 046989ba790c1b12be9fe4a07f46c502a62eeb7b
Author: SJ Park <sj@kernel.org>

mm/damon/core: introduce damon_prep struct

This commit introduces the damon_prep data structure to specify preparatory
actions for DAMON probes. It also adds DAMON_PREP_SET_PGIDLE as the initial
preparation action for access monitoring.

> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index 644daf5a16560..0b396c2456d05 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c

[ ... ]

> @@ -111,6 +111,28 @@ int damon_select_ops(struct damon_ctx *ctx, enum damon_ops_id id)
>  	return err;
>  }
>  
> +struct damon_prep *damon_new_prep(enum damon_prep_action action)
> +{
> +	struct damon_prep *prep;
> +
> +	prep = kmalloc_obj(*prep);
> +	if (!prep)
> +		return NULL;
> +	prep->action = action;
> +	INIT_LIST_HEAD(&prep->list);
> +	return prep;
> +}

[Severity: Low]
Is there a missing exported cleanup API for struct damon_prep?

Since damon_new_prep() is exposed for external modules to allocate a new
prep structure, do they need a corresponding exported destructor (like
damon_destroy_prep()) to clean it up if an error occurs before it is
attached to a probe via damon_add_prep()?

Currently, damon_free_prep() is static, which forces any external caller to
manually call kfree() on error paths, potentially breaking the subsystem's
abstraction.

> +
> +void damon_add_prep(struct damon_probe *p, struct damon_prep *prep)
> +{
> +	list_add_tail(&prep->list, &p->preps);
> +}
> +
> +static void damon_free_prep(struct damon_prep *p)
> +{
> +	kfree(p);
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260901043417.2165-1-sj@kernel.org?part=5