Re: [RFC PATCH 02/10] mm/damon/core: add damon_new_region() debug_sanity check

[SeongJae Park <sj@kernel.org>]

On Sat, 21 Feb 2026 11:36:19 -0800 SeongJae Park <sj@kernel.org> wrote:

> damon_new_region() is supposed to be called with only valid address
> range arguments.  Do the check under DAMON_DEBUG_SANITY.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
>  mm/damon/core.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/mm/damon/core.c b/mm/damon/core.c
> index 602b85ef23597..a7f5748c1fe17 100644
> --- a/mm/damon/core.c
> +++ b/mm/damon/core.c
> @@ -109,6 +109,22 @@ int damon_select_ops(struct damon_ctx *ctx, enum damon_ops_id id)
>  	return err;
>  }
>  
> +#ifdef CONFIG_DAMON_DEBUG_SANITY
> +static void damon_verify_new_region(unsigned long start, unsigned long end)
> +{
> +

I'll remove the above unnecessary new line in the next spin.

> +	if (start < end)
> +		return;
> +	pr_err("damon_new_region() s called with start %lu >= end %lu!\n",
> +			start, end);
> +	WARN_ONCE();
> +}
> +#else
> +static void damon_verify_new_region(unsigned long start, unsigned long end)
> +{
> +}
> +#endif
> +
>  /*
>   * Construct a damon_region struct
>   *
> @@ -122,6 +138,8 @@ struct damon_region *damon_new_region(unsigned long start, unsigned long end)
>  	if (!region)
>  		return NULL;
>  
> +	damon_verify_new_region(start, end);
> +

The verification may better to be made before the above region allocation.
I'll move it to the beginning of this function in the next spin.

>  	region->ar.start = start;
>  	region->ar.end = end;
>  	region->nr_accesses = 0;
> -- 
> 2.47.3


Thanks,
SJ