Re: [PATCH 04/12] mm/damon/core: validate number of probes in valid_probe_params()

[Kunwu Chan <kunwu.chan@gmail.com>]

On Tue,  1 Sep 2026 22:47:37 -0700 SJ Park <sj@kernel.org> wrote:

> Each DAMON context is allowed to have only up to DAMON_MAX_PROBES
> probes.  The central place for validating DAMON probe parameters,
> damon_valid_probe_params(), is not validating the upper limit, though.
> Do the validation.
> 
> Signed-off-by: SJ Park <sj@kernel.org>
> ---
>  mm/damon/core.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index 4d28eb033fc4a..c010f686d033e 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -1420,6 +1420,13 @@ static bool damon_valid_probe_params(struct damon_ctx *ctx)
>  	unsigned char max_probe_hits;
>  	struct damon_probe *probe;
>  	unsigned int wsum, wsum_to_add;
> +	int nr_probes;
> +
> +	nr_probes = 0;
> +	damon_for_each_probe(probe, ctx)
> +		nr_probes++;
> +	if (nr_probes > DAMON_MAX_PROBES)
> +		return false;

Hi SJ,

Thanks for the explanation.

I agree that `DAMON_MAX_PROBES` is better enforced in the core layer,
so that all callers share the same validation path without duplicating
the limit in the sysfs layer.

Reviewed-by: Kunwu Chan <kunwu.chan@gmail.com>

Thanks,
Kunwu

>  
>  	if (!damon_has_probe_weights(ctx))
>  		return true;
> -- 
> 2.47.3
> 

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