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Date:   Tue, 19 Oct 2021 12:51:47 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Shakeel Butt <shakeelb@google.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Vasily Averin <vvs@virtuozzo.com>,
        Roman Gushchin <guro@fb.com>, cgroups@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Michal Hocko <mhocko@suse.com>,
        Muchun Song <songmuchun@bytedance.com>
Subject: Re: [PATCH v3] memcg, kmem: further deprecate kmem.limit_in_bytes
Message-Id: <20211019125147.0ad010f318bbd8233cadcdae@linux-foundation.org>
In-Reply-To: <20211019153408.2916808-1-shakeelb@google.com>
References: <20211019153408.2916808-1-shakeelb@google.com>
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On Tue, 19 Oct 2021 08:34:08 -0700 Shakeel Butt <shakeelb@google.com> wrote:

> The deprecation process of kmem.limit_in_bytes started with the commit
> 0158115f702 ("memcg, kmem: deprecate kmem.limit_in_bytes") which also
> explains in detail the motivation behind the deprecation. To summarize,
> it is the unexpected behavior on hitting the kmem limit. This patch
> moves the deprecation process to the next stage by disallowing to set
> the kmem limit. In future we might just remove the kmem.limit_in_bytes
> file completely.
> 
> ...
>
> @@ -3791,10 +3766,8 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
>  			ret = mem_cgroup_resize_max(memcg, nr_pages, true);
>  			break;
>  		case _KMEM:
> -			pr_warn_once("kmem.limit_in_bytes is deprecated and will be removed. "
> -				     "Please report your usecase to linux-mm@kvack.org if you "
> -				     "depend on this functionality.\n");
> -			ret = memcg_update_kmem_max(memcg, nr_pages);
> +			/* kmem.limit_in_bytes is deprecated. */
> +			ret = -ENOTSUPP;
>  			break;
>  		case _TCP:
>  			ret = memcg_update_tcp_max(memcg, nr_pages);

checkpatch said "ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP"?