linux-kernel - Re: [PATCH] memcg: account security cred as well to kmemcg

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Message-ID: <CALvZod6deN4tGhcWygDGOrUaozAY7ikjdrECS=EyNLqGz7VPYQ@mail.gmail.com>
Date:   Fri, 6 Dec 2019 21:06:58 -0800
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Roman Gushchin <guro@...com>, Linux MM <linux-mm@...ck.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...e.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] memcg: account security cred as well to kmemcg

On Fri, Dec 6, 2019 at 4:13 PM Andrew Morton <akpm@...ux-foundation.org> wrote:
>
> On Thu,  5 Dec 2019 14:37:21 -0800 Shakeel Butt <shakeelb@...gle.com> wrote:
>
> > The cred_jar kmem_cache is already memcg accounted in the current
> > kernel but cred->security is not. Account cred->security to kmemcg.
> >
> > Recently we saw high root slab usage on our production and on further
> > inspection, we found a buggy application leaking processes. Though that
> > buggy application was contained within its memcg but we observe much
> > more system memory overhead, couple of GiBs, during that period. This
> > overhead can adversely impact the isolation on the system. One of source
> > of high overhead, we found was cred->secuity objects.
>
> A bit of an oversight and the fix is simple.  Is it worth a cc:stable?

Yes, I think it is simple and safe enough for stable.