Re: [RFC v1] mm: add page preemption

[Matthew Wilcox]

On Sun, Oct 20, 2019 at 09:43:04PM +0800, Hillf Danton wrote:
> First on the page side, page->prio that is used to mirror the prio
> of page owner tasks is added, and a couple of helpers for setting,
> copying and comparing page->prio to help to add pages to lru.

Um, no.  struct page is 64 bytes and shall remain so without a very very
good reason.

> @@ -197,6 +198,10 @@ struct page {
>  	/* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */
>  	atomic_t _refcount;
>  
> +#ifdef CONFIG_PAGE_PREEMPTION
> +	int prio; /* mirror page owner task->prio */
> +#endif
> +
>  #ifdef CONFIG_MEMCG
>  	struct mem_cgroup *mem_cgroup;
>  #endif