parca-agent not able to find binaries which chroot to a non-/ mount

[axinojolais]

Describe the bug
Logs flooded with :

parca-agent.parca-agent-svc[49385]: level=warn name=parca-agent ts=2024-06-03T09:22:20.712072211Z caller=cpu.go:719 component=cpu_profiler msg="failed to add unwind table" pid=50350 err="failed to prefetch process info: failed to get executable object file for /proc/50350/root/usr/bin/rsync: error opening /proc/50350/root/usr/bin/rsync: open /proc/50350/root/usr/bin/rsync: no such file or directory"

I suspect this is because rsync chroots to a mounted filesystem which is not /, and so /proc/pid/root does not point at /

To Reproduce
Try to profile any daemon that chroots. rsyncd tries to chroot by default to the path given in the config stanza, if any.

Expected behavior
parca-agent can find the binary

Software (please complete the following information):

• Parca Agent Version: parca-agent, version 0.30.0 (commit: da59a7c04e2e9ee29fe5871a0fd2d2964a7701cc, date: 2024-03-04T20:55:59Z), arch: amd64 (latest/edge snap)

Environment (please complete the following information):

• Linux Distribution: Ubuntu 22.04
• Linux Version: Ubuntu 6.5.0-15-generic
• Arch: x86_64

[jnsgruk]

Hey @axinojolais - sorry for the late reply on this one. I can see you're running the snap, but I don't think that's actually causing the problem.

To confirm, could you try downloading and running the upstream parca-binary and just see if you get the same issue?

[dyumin]

I have similar problem.
parca was unable to symbolize haproxy running with chroot /var/empty

parca-agent[1025061]: level=debug name=parca-agent ts=2024-10-24T14:53:29.807803765Z caller=cpu.go:414 component=cpu_profiler msg="failed to prefetch process info" pid=1031735 err="failed to get executable object file for /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: error opening /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: open /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: no such file or directory"

parca-agent[1025061]: level=debug name=parca-agent ts=2024-10-24T14:53:28.859538512Z caller=cpu.go:399 component=cpu_profiler msg="failed to add unwind table due to a procfs race" pid=1031735 err="setUnwindTableForMapping for executable /opt/hapee-2.6/sbin/hapee-lb starting at 0x560f38d58fdc failed: open /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: no such file or directory"

parca-agent[1025061]: level=debug name=parca-agent ts=2024-10-24T14:53:28.857271022Z caller=cpu.go:377 component=cpu_profiler msg="failed to fetch process info" pid=1031735 err="failed to get executable object file for /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: error opening /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: open /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: no such file or directory"

parca-agent[1025061]: level=debug name=parca-agent ts=2024-10-24T14:53:28.380460363Z caller=cpu.go:768 component=cpu_profiler msg="failed to get process info" pid=1031735 err="failed to get executable object file for /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: error opening /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: open /proc/1031735/root/opt/hapee-2.6/sbin/hapee-lb: no such file or directory"

after disabling chroot everything worked fine