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From:   Song Liu <song@kernel.org>
Date:   Mon, 27 Jul 2020 15:44:47 -0700
Message-ID: <CAPhsuW4D0TYtvdexBnn5icg3EdTaBRu7ON8Q0REJ_hPRKx4aeA@mail.gmail.com>
Subject: Re: [PATCH bpf-next v2 29/35] bpf: libbpf: cleanup RLIMIT_MEMLOCK usage
To:     Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc:     Roman Gushchin <guro@fb.com>, bpf <bpf@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Kernel Team <kernel-team@fb.com>,
        open list <linux-kernel@vger.kernel.org>
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On Mon, Jul 27, 2020 at 3:07 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Mon, Jul 27, 2020 at 12:21 PM Roman Gushchin <guro@fb.com> wrote:
> >
> > As bpf is not using memlock rlimit for memory accounting anymore,
> > let's remove the related code from libbpf.
> >
> > Bpf operations can't fail because of exceeding the limit anymore.
> >
>
> They can't in the newest kernel, but libbpf will keep working and
> supporting old kernels for a very long time now. So please don't
> remove any of this.
>
> But it would be nice to add a detection of whether kernel needs a
> RLIMIT_MEMLOCK bump or not. Is there some simple and reliable way to
> detect this from user-space?
>

Agreed. We will need compatibility or similar detection for perf as well.

Thanks,
Song