Re: [PATCH net-next v9 2/4] page_pool: halve BIAS_MAX for multiple user references of a fragment

[Mina Almasry <almasrymina@google.com>]

On Mon, Dec 11, 2023 at 8:47 PM Liang Chen <liangchen.linux@gmail.com> wrote:
>
> Referring to patch [1], in order to support multiple users referencing the
> same fragment and prevent overflow from pp_ref_count growing, the initial
> value of pp_ref_count is halved, leaving room for pp_ref_count to increment
> before the page is drained.
>
> [1]
> https://lore.kernel.org/all/20211009093724.10539-3-linyunsheng@huawei.com/
>
> Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>

Reviewed-by: Mina Almasry <almarsymina@google.com>

> ---
>  net/core/page_pool.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 106220b1f89c..436f7ffea7b4 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -26,7 +26,7 @@
>  #define DEFER_TIME (msecs_to_jiffies(1000))
>  #define DEFER_WARN_INTERVAL (60 * HZ)
>
> -#define BIAS_MAX       LONG_MAX
> +#define BIAS_MAX       (LONG_MAX >> 1)
>
>  #ifdef CONFIG_PAGE_POOL_STATS
>  /* alloc_stat_inc is intended to be used in softirq context */
> --
> 2.31.1
>
>


-- 
Thanks,
Mina