linux-kernel - Re: [PATCH] memcg, kmem: further deprecate kmem.limit_in

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Message-ID: <CALvZod5WBeZB_kCGqO9EXGxqpkdPsZq7Q-MwVFv014ukECiTxw@mail.gmail.com>
Date:   Wed, 18 Nov 2020 11:54:13 -0800
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Roman Gushchin <guro@...com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] memcg, kmem: further deprecate kmem.limit_in_bytes

On Wed, Nov 18, 2020 at 11:46 AM Roman Gushchin <guro@...com> wrote:
>
> On Wed, Nov 18, 2020 at 09:57:26AM -0800, Shakeel Butt 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.
> >
> > Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
>
> The first stage was done over a year ago, so if there were no complains
> it feels like it's a good time to move forward.
>
> Acked-by: Roman Gushchin <guro@...com>

Thanks.

>
> The only question I have is if it's better to return -EINVAL or -ENOTSUPP.
> The latter option could be more convenient for userspace, because it will
> be clear that the kernel is not supporting the functionality, rather than
> the passed value is incorrect (e.g. if the value is read from a config, provided
> by a user). I'm not sure though, just an idea.
>

Let's see what others say. I am ok with -ENOTSUPP as well.