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From:   Shakeel Butt <shakeelb@google.com>
Date:   Tue, 19 Oct 2021 13:03:32 -0700
Message-ID: <CALvZod7QPR1Zz3XcN1CJvm_DuWomoR7MrS7uEyCBHNMX5c8AiQ@mail.gmail.com>
Subject: Re: [PATCH v3] memcg, kmem: further deprecate kmem.limit_in_bytes
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Vasily Averin <vvs@virtuozzo.com>,
        Roman Gushchin <guro@fb.com>,
        Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Michal Hocko <mhocko@suse.com>,
        Muchun Song <songmuchun@bytedance.com>
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On Tue, Oct 19, 2021 at 12:51 PM Andrew Morton
<akpm@linux-foundation.org> wrote:
>
> 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"?

I should have run checkpatch and Andrew, please replace ENOTSUPP with
EOPNOTSUPP. Thanks for catching this.