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Subject: Re: [PATCH] fs: nfs: return per memcg count for xattr shrinkers
Date:   Wed, 30 Sep 2020 20:46:48 +0000
From:   Frank van der Linden <fllinden@amazon.com>
To:     Yang Shi <shy828301@gmail.com>
CC:     <trond.myklebust@hammerspace.com>, <anna.schumaker@netapp.com>,
        <linux-nfs@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Message-ID: <20200930204648.GA9098@dev-dsk-fllinden-2c-c1893d73.us-west-2.amazon.com>
References: <20200927114220.141530-1-shy828301@gmail.com>
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On Sun, Sep 27, 2020 at 04:42:20AM -0700, Yang Shi wrote:
> 
> The list_lru_count() returns the pre node count, but the new xattr
> shrinkers are memcg aware, so the shrinkers should return per memcg
> count by calling list_lru_shrink_count() instead.  Otherwise over-shrink
> might be experienced.  The problem was spotted by visual code
> inspection.
> 
> Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
> Cc: Anna Schumaker <anna.schumaker@netapp.com>
> Cc: Frank van der Linden <fllinden@amazon.com>
> Signed-off-by: Yang Shi <shy828301@gmail.com>
> ---
>  fs/nfs/nfs42xattr.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/nfs/nfs42xattr.c b/fs/nfs/nfs42xattr.c
> index 86777996cfec..6e5f34916937 100644
> --- a/fs/nfs/nfs42xattr.c
> +++ b/fs/nfs/nfs42xattr.c
> @@ -882,7 +882,7 @@ nfs4_xattr_cache_count(struct shrinker *shrink, struct shrink_control *sc)
>  {
>         unsigned long count;
> 
> -       count = list_lru_count(&nfs4_xattr_cache_lru);
> +       count = list_lru_shrink_count(&nfs4_xattr_cache_lru, sc);
>         return vfs_pressure_ratio(count);
>  }
> 
> @@ -976,7 +976,7 @@ nfs4_xattr_entry_count(struct shrinker *shrink, struct shrink_control *sc)
>         lru = (shrink == &nfs4_xattr_large_entry_shrinker) ?
>             &nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
> 
> -       count = list_lru_count(lru);
> +       count = list_lru_shrink_count(lru, sc);
>         return vfs_pressure_ratio(count);
>  }
> 
> --
> 2.26.2
> 

Yep, thanks.

Reviewed-by: Frank van der Linden <fllinden@amazon.com>