linux-kernel - Re: [PATCH] mm: Move check for SHRINKER_NUMA_AWARE to do_shrink

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Date:   Thu, 2 Aug 2018 09:47:06 -0700
From:   Yang Shi <shy828301@...il.com>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>, mhocko@...e.com,
        aryabinin@...tuozzo.com, ying.huang@...el.com,
        penguin-kernel@...ove.sakura.ne.jp, willy@...radead.org,
        Shakeel Butt <shakeelb@...gle.com>, jbacik@...com,
        linux-mm@...ck.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: Move check for SHRINKER_NUMA_AWARE to do_shrink_slab()

On Thu, Aug 2, 2018 at 4:00 AM, Kirill Tkhai <ktkhai@...tuozzo.com> wrote:
> In case of shrink_slab_memcg() we do not zero nid, when shrinker
> is not numa-aware. This is not a real problem, since currently
> all memcg-aware shrinkers are numa-aware too (we have two:

Actually, this is not true. huge_zero_page_shrinker is NOT numa-aware.
deferred_split_shrinker is numa-aware.

Thanks,
Yang


> super_block shrinker and workingset shrinker), but something may
> change in the future.
>
> (Andrew, this may be merged to mm-iterate-only-over-charged-shrinkers-during-memcg-shrink_slab)
>
> Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com>
> ---
>  mm/vmscan.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index ea0a46166e8e..0d980e801b8a 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -455,6 +455,9 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
>                                           : SHRINK_BATCH;
>         long scanned = 0, next_deferred;
>
> +       if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
> +               nid = 0;
> +
>         freeable = shrinker->count_objects(shrinker, shrinkctl);
>         if (freeable == 0 || freeable == SHRINK_EMPTY)
>                 return freeable;
> @@ -680,9 +683,6 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
>                         .memcg = memcg,
>                 };
>
> -               if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
> -                       sc.nid = 0;
> -
>                 ret = do_shrink_slab(&sc, shrinker, priority);
>                 if (ret == SHRINK_EMPTY)
>                         ret = 0;
>