Re: [RFC PATCH 1/1] mm: only use old generation and stable tier for madv_pageout

[Matthew Wilcox]

On Fri, Oct 13, 2023 at 07:30:28PM +0800, zhaoyang.huang wrote:
> From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
> 
> Dropping pages of young generation or unstable tier via madvise could
> make the system experience heavy page thrashing and IO pressure.

... then userspace should not do that?

> @@ -5091,6 +5091,7 @@ static int get_tier_idx(struct lruvec *lruvec, int type)
>  
>  	return tier - 1;
>  }
> +EXPORT_SYMBOL_GPL(get_tier_idx);

Why would this need to be exported to modules in order to be used by
madvise?  Is this patch just a trojan horse so you can use get_tier_idx
in your own module?  NAK.