Re: [PATCH net-next 1/2] net: page_pool: Expose internal limit

[Ilias Apalodimas]

On Mon, 22 Sept 2025 at 12:19, Tariq Toukan <tariqt@xxxxxxxxxx> wrote:
>
> From: Dragos Tatulea <dtatulea@xxxxxxxxxx>
>
> page_pool_init() has a check for pool_size < 32K. But page_pool users
> have no access to this limit so there is no way to trim the pool_size in
> advance. The E2BIG error doesn't help much for retry as the driver has
> to guess the next size and retry.
>
> This patch exposes this limit to in the page_pool header.
>
> Signed-off-by: Dragos Tatulea <dtatulea@xxxxxxxxxx>
> Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxx>

Reviewed-by: Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx>

> ---
>  include/net/page_pool/types.h | 2 ++
>  net/core/page_pool.c          | 2 +-
>  2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
> index 1509a536cb85..22aee9a65a26 100644
> --- a/include/net/page_pool/types.h
> +++ b/include/net/page_pool/types.h
> @@ -163,6 +163,8 @@ struct pp_memory_provider_params {
>         const struct memory_provider_ops *mp_ops;
>  };
>
> +#define PAGE_POOL_SIZE_LIMIT 32768
> +
>  struct page_pool {
>         struct page_pool_params_fast p;
>
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 36a98f2bcac3..1f0fdfb02f08 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -214,7 +214,7 @@ static int page_pool_init(struct page_pool *pool,
>                 ring_qsize = pool->p.pool_size;
>
>         /* Sanity limit mem that can be pinned down */
> -       if (ring_qsize > 32768)
> +       if (ring_qsize > PAGE_POOL_SIZE_LIMIT)
>                 return -E2BIG;
>
>         /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
> --
> 2.31.1
>