Re: [RFC PATCH v2 1/4] mm/damon: Generic context creation for modules

[SeongJae Park <sj@kernel.org>]

On Tue, 10 Mar 2026 16:24:17 +0000 <gutierrez.asier@huawei-partners.com> wrote:

> From: Asier Gutierrez <gutierrez.asier@huawei-partners.com>
> 
> It is more elegant to have a generic version of new context creation
> which receives the mode as a parameter.
> 
> Signed-off-by: Asier Gutierrez <gutierrez.asier@huawei-partners.com>
> Co-developed-by: Anatoly Stepanov <stepanov.anatoly@huawei.com>
> ---
>  mm/damon/lru_sort.c       | 5 +++--
>  mm/damon/modules-common.c | 6 +++---
>  mm/damon/modules-common.h | 4 ++--
>  mm/damon/reclaim.c        | 5 +++--
>  4 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
> index 7bc5c0b2aea3..143ee0b21da6 100644
> --- a/mm/damon/lru_sort.c
> +++ b/mm/damon/lru_sort.c
> @@ -287,7 +287,8 @@ static int damon_lru_sort_apply_parameters(void)
>  	unsigned int hot_thres, cold_thres;
>  	int err;
>  
> -	err = damon_modules_new_paddr_ctx_target(&param_ctx, &param_target);
> +	err = damon_modules_new_ctx_target(&param_ctx, &param_target,
> +				DAMON_OPS_PADDR);

I like the name of the function is becoming shorter.  But I'm not happy with
the fact the resulting calling code becomes longer.

I understand you are doing this extension because you want a version of the
function for vaddr.  What about introducing another dedicated function, say,
damon_modules_new_vaddr_ctx_target() ?

And you can avoid duplicates between damon_modules_new_{p,v}addr_ctx_target()
by implementing internal function, say, damon_modules_new_ctx_target() that
receives the damon_ops_id.  And damon_modules_new_{P,v}addr_ctx_target() will
just wrappers of damon_modules_new_ctx_target().

>  	if (err)
>  		return err;
>  
> @@ -479,7 +480,7 @@ static int __init damon_lru_sort_init(void)
>  		err = -ENOMEM;
>  		goto out;
>  	}
> -	err = damon_modules_new_paddr_ctx_target(&ctx, &target);
> +	err = damon_modules_new_ctx_target(&ctx, &target, DAMON_OPS_PADDR);

Ditto.

>  	if (err)
>  		goto out;
>  
> diff --git a/mm/damon/modules-common.c b/mm/damon/modules-common.c
> index 86d58f8c4f63..ae50b2fa3a86 100644
> --- a/mm/damon/modules-common.c
> +++ b/mm/damon/modules-common.c
> @@ -14,8 +14,8 @@
>   * @ctxp:	Pointer to save the point to the newly created context
>   * @targetp:	Pointer to save the point to the newly created target
>   */
> -int damon_modules_new_paddr_ctx_target(struct damon_ctx **ctxp,
> -		struct damon_target **targetp)
> +int damon_modules_new_ctx_target(struct damon_ctx **ctxp,
> +		struct damon_target **targetp, enum damon_ops_id mode)

Nit.  I'd suggest 'ops_id' as the parameter name, instead of 'mode'.

>  {
>  	struct damon_ctx *ctx;
>  	struct damon_target *target;
> @@ -24,7 +24,7 @@ int damon_modules_new_paddr_ctx_target(struct damon_ctx **ctxp,
>  	if (!ctx)
>  		return -ENOMEM;
>  
> -	if (damon_select_ops(ctx, DAMON_OPS_PADDR)) {
> +	if (damon_select_ops(ctx, mode)) {
>  		damon_destroy_ctx(ctx);
>  		return -EINVAL;
>  	}
> diff --git a/mm/damon/modules-common.h b/mm/damon/modules-common.h
> index f103ad556368..379b49c6a617 100644
> --- a/mm/damon/modules-common.h
> +++ b/mm/damon/modules-common.h
> @@ -45,5 +45,5 @@
>  	module_param_named(nr_##qt_exceed_name, stat.qt_exceeds, ulong,	\
>  			0400);
>  
> -int damon_modules_new_paddr_ctx_target(struct damon_ctx **ctxp,
> -		struct damon_target **targetp);
> +int damon_modules_new_ctx_target(struct damon_ctx **ctxp,
> +		struct damon_target **targetp, enum damon_ops_id mode);
> diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
> index 43d76f5bed44..24786a58683a 100644
> --- a/mm/damon/reclaim.c
> +++ b/mm/damon/reclaim.c
> @@ -197,7 +197,8 @@ static int damon_reclaim_apply_parameters(void)
>  	struct damos_filter *filter;
>  	int err;
>  
> -	err = damon_modules_new_paddr_ctx_target(&param_ctx, &param_target);
> +	err = damon_modules_new_ctx_target(&param_ctx, &param_target,
> +				DAMON_OPS_PADDR);
>  	if (err)
>  		return err;
>  
> @@ -381,7 +382,7 @@ static int __init damon_reclaim_init(void)
>  		err = -ENOMEM;
>  		goto out;
>  	}
> -	err = damon_modules_new_paddr_ctx_target(&ctx, &target);
> +	err = damon_modules_new_ctx_target(&ctx, &target, DAMON_OPS_PADDR);
>  	if (err)
>  		goto out;
>  
> -- 
> 2.43.0


Thanks,
SJ