Date:   Sat, 18 Mar 2023 15:16:45 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Jiri Olsa <olsajiri@gmail.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Hao Luo <haoluo@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        bpf@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-perf-users@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        Stanislav Fomichev <sdf@google.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Namhyung Kim <namhyung@gmail.com>,
        Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCHv3 bpf-next 0/9] mm/bpf/perf: Store build id in file object
Message-ID: <ZBXV3crf/wX5D9lo@casper.infradead.org>
References: <20230316170149.4106586-1-jolsa@kernel.org>
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 <ZBV3beyxYhKv/kMp@krava>
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On Sat, Mar 18, 2023 at 09:33:49AM +0100, Jiri Olsa wrote:
> On Thu, Mar 16, 2023 at 05:34:41PM +0000, Matthew Wilcox wrote:
> > On Thu, Mar 16, 2023 at 06:01:40PM +0100, Jiri Olsa wrote:
> > > hi,
> > > this patchset adds build id object pointer to struct file object.
> > > 
> > > We have several use cases for build id to be used in BPF programs
> > > [2][3].
> > 
> > Yes, you have use cases, but you never answered the question I asked:
> > 
> > Is this going to be enabled by every distro kernel, or is it for special
> > use-cases where only people doing a very specialised thing who are
> > willing to build their own kernels will use it?
> 
> I hope so, but I guess only time tell.. given the response by Ian and Andrii
> there are 3 big users already

So the whole "There's a config option to turn it off" shtick is just a
fig-leaf.  I won't ever see it turned off.  You're imposing the cost of
this on EVERYONE who runs a distro kernel.  And almost nobody will see
any benefits from it.  Thanks for admitting that.