Re: [PATCH for v5.8 3/3] mm/memory: fix IO cost for anonymous page

[Vlastimil Babka]

On 6/16/20 8:16 AM, js1304@xxxxxxxxx wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> 
> With synchronous IO swap device, swap-in is directly handled in fault
> code. Since IO cost notation isn't added there, with synchronous IO swap
> device, LRU balancing could be wrongly biased. Fix it to count it
> in fault code.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
>  mm/memory.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index bc6a471..3359057 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3143,6 +3143,14 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
>  				if (err)
>  					goto out_page;
>  
> +				/*
> +				 * XXX: Move to lru_cache_add() when it
> +				 * supports new vs putback
> +				 */
> +				spin_lock_irq(&page_pgdat(page)->lru_lock);
> +				lru_note_cost_page(page);
> +				spin_unlock_irq(&page_pgdat(page)->lru_lock);
> +
>  				lru_cache_add(page);
>  				swap_readpage(page, true);
>  			}
>