Re: [PATCH] mm: workingset: fix premature shadow node shrinking with cgroups

[Vladimir Davydov]

On Tue, Mar 21, 2017 at 08:53:20PM -0400, Johannes Weiner wrote:
> 0a6b76dd23fa ("mm: workingset: make shadow node shrinker memcg aware")
> enabled cgroup-awareness in the shadow node shrinker, but forgot to
> also enable cgroup-awareness in the list_lru the shadow nodes sit on.
> 
> Consequently, all shadow nodes are sitting on a global (per-NUMA node)
> list, while the shrinker applies the limits according to the amount of
> cache in the cgroup its shrinking. The result is excessive pressure on
> the shadow nodes from cgroups that have very little cache.
> 
> Enable memcg-mode on the shadow node LRUs, such that per-cgroup limits
> are applied to per-cgroup lists.
> 
> Fixes: 0a6b76dd23fa ("mm: workingset: make shadow node shrinker memcg aware")
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.6+

Acked-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>

> ---
>  mm/workingset.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/workingset.c b/mm/workingset.c
> index ac839fca0e76..eda05c71fa49 100644
> --- a/mm/workingset.c
> +++ b/mm/workingset.c
> @@ -532,7 +532,7 @@ static int __init workingset_init(void)
>  	pr_info("workingset: timestamp_bits=%d max_order=%d bucket_order=%u\n",
>  	       timestamp_bits, max_order, bucket_order);
>  
> -	ret = list_lru_init_key(&shadow_nodes, &shadow_nodes_key);
> +	ret = __list_lru_init(&shadow_nodes, true, &shadow_nodes_key);
>  	if (ret)
>  		goto err;
>  	ret = register_shrinker(&workingset_shadow_shrinker);
> -- 
> 2.12.0
>