Re: [PATCH] mm: skip current when memcg reclaim

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 15 Oct 2021 14:15:29 +0800 Huangzhaoyang <huangzhaoyang@gmail.com> wrote:

> From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> 
> Sibling thread of the same process could refault the reclaimed pages
> in the same time, which would be typical in None global reclaim and
> introduce thrashing.

"None" -> "node", I assume?

> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2841,6 +2841,11 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
>  				sc->memcg_low_skipped = 1;
>  				continue;
>  			}
> +			/*
> +			 * Don't bother current when its memcg is below low
> +			 */

The comment explains what the code is doing, but the code itself
already does this.  Please can we have a comment that explains *why*
the code is doing this?


> +			if (get_mem_cgroup_from_mm(current->mm) == memcg)
> +				continue;
>  			memcg_memory_event(memcg, MEMCG_LOW);
>  		}