netdev - Re: [PATCH bpf-next v3 00/13] bpf: Introduce selectable memcg for bpf map

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Date:   Wed, 7 Sep 2022 05:45:15 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Yafang Shao <laoar.shao@...il.com>
Cc:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        kafai@...com, songliubraving@...com, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
        haoluo@...gle.com, jolsa@...nel.org, hannes@...xchg.org,
        mhocko@...nel.org, roman.gushchin@...ux.dev, shakeelb@...gle.com,
        songmuchun@...edance.com, akpm@...ux-foundation.org,
        lizefan.x@...edance.com, cgroups@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH bpf-next v3 00/13] bpf: Introduce selectable memcg for
 bpf map

On Wed, Sep 07, 2022 at 05:43:31AM -1000, Tejun Heo wrote:
> Hello,
> 
> On Fri, Sep 02, 2022 at 02:29:50AM +0000, Yafang Shao wrote:
> ...
> > This patchset tries to resolve the above two issues by introducing a
> > selectable memcg to limit the bpf memory. Currently we only allow to
> > select its ancestor to avoid breaking the memcg hierarchy further. 
> > Possible use cases of the selectable memcg as follows,
> 
> As discussed in the following thread, there are clear downsides to an
> interface which requires the users to specify the cgroups directly.
> 
>  https://lkml.kernel.org/r/YwNold0GMOappUxc@slm.duckdns.org
> 
> So, I don't really think this is an interface we wanna go for. I was hoping
> to hear more from memcg folks in the above thread. Maybe ping them in that
> thread and continue there?

Ah, another thing. If the memcg accounting is breaking things right now, we
can easily introduce a memcg disable flag for bpf memory. That should help
alleviating the immediate breakage while we figure this out.

Thanks.

-- 
tejun