Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <CABWYdi1ZKR=jmKnjoJTik08Q9uJBvyZ4W0C29iPiUJ5ef1obvw@mail.gmail.com>
 <20191205123302.GA25750@kernel.org> <CABWYdi1+E7MQD8mC2xQfSP0m9_WFdx9mbLkw-36tJ8EtLaw2Jg@mail.gmail.com>
In-Reply-To: <CABWYdi1+E7MQD8mC2xQfSP0m9_WFdx9mbLkw-36tJ8EtLaw2Jg@mail.gmail.com>
From:   Marek Majkowski <marek@cloudflare.com>
Date:   Tue, 4 Feb 2020 15:09:48 +0000
Message-ID: <CAJPywTKC8=O0zmNm-W4OUENpoZfrbr1Ts38gQw2ZA608_u5wpw@mail.gmail.com>
Subject: Re: perf not picking up symbols for namespaced processes
To:     Ivan Babrou <ivan@cloudflare.com>,
        kernel-team <kernel-team@cloudflare.com>
Cc:     Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Jiri Olsa <jolsa@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Namhyung Kim <namhyung@kernel.org>, sashal@kernel.org,
        Kenton Varda <kenton@cloudflare.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Dec 6, 2019 at 2:17 AM Ivan Babrou <ivan@cloudflare.com> wrote:
>
> I'm not very good at this, but the following works for me. If you this
> is in general vicinity of what you expected, I can email patch
> properly.
>

Thanks for the patch, I can confirm it works. I had this problem today
when playing
with gvisor. Gvisor is starting up in a fresh mount namespace and perf fails
to read the symbols. Stracing perf shows:

11913 openat(AT_FDCWD, "/proc/9512/ns/mnt", O_RDONLY) = 197
11913 setns(197, CLONE_NEWNS) = 0
11913 stat("/home/marek/bin/runsc-debug", 0x7fffffff8480) = -1 ENOENT
(No such file or directory)
11913 setns(196, CLONE_NEWNS) = 0

Which of course makes no sense - the runsc-debug binary does not exist in the
empty mount namespace of the restricted runsc process.

Marek