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podman-remote wait: fails with read /proc/N/cgroup: no such process #16383

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edsantiago opened this issue Nov 2, 2022 · 4 comments · Fixed by #16504
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podman-remote wait: fails with read /proc/N/cgroup: no such process #16383

edsantiago opened this issue Nov 2, 2022 · 4 comments · Fixed by #16504
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flakes Flakes from Continuous Integration locked - please file new issue/PR Assist humans wanting to comment on an old issue or PR with locked comments.

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@edsantiago
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Seen just now in remote f36-aarch64 root. Almost certainly a flake:

[+0098s] not ok 53 podman --noout run should print output
...
# podman-remote --noout run -d --name test quay.io/libpod/testimage:20221018 echo hi
# podman-remote wait test
Error: read /proc/14628/cgroup: no such process
[ rc=125 (** EXPECTED 0 **) ]

My flake logs find one other instance, September 14 in f36 rootless, but that one is preceded by other errors. This one, no prior indications of failure.
@edsantiago edsantiago added flakes Flakes from Continuous Integration remote Problem is in podman-remote labels Nov 2, 2022
@github-actions github-actions bot removed the remote Problem is in podman-remote label Nov 2, 2022
@edsantiago edsantiago mentioned this issue Nov 2, 2022
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@edsantiago
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Another one, also remote, but f37 this time instead of f36

@vrothberg
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@giuseppe, any idea what could cause it?

@giuseppe
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it is a race when reading the process cgroup using os.ReadFile().

What happens is that the process terminates between the open("/proc/$PID/cgroup") succeded and the following read.

It can be easily reproduced with:

$ sleep 1 & (sleep 2; cat -) < /proc/$!/cgroup 
[1] 1083377
cat: -: No such process

giuseppe added a commit to giuseppe/libpod that referenced this issue Nov 14, 2022
@giuseppe
libpod: treat ESRCH from /proc/PID/cgroup as ENOENT
36f8dfa 
when reading from the /proc/$PID/cgroup file, treat ESRCH in the same
way as ENOENT since the kernel returns ESRCH if the file was opened
correctly but the target process exited before the open could be
performed.

Closes: containers#16383

[NO NEW TESTS NEEDED] it is a race condition that is difficult to
reproduce.

Signed-off-by: Giuseppe Scrivano <[email protected]>
@giuseppe giuseppe mentioned this issue Nov 14, 2022
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@giuseppe
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PR here: #16504

@github-actions github-actions bot added the locked - please file new issue/PR Assist humans wanting to comment on an old issue or PR with locked comments. label Sep 10, 2023
@github-actions github-actions bot locked as resolved and limited conversation to collaborators Sep 10, 2023
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libpod: treat ESRCH from /proc/PID/cgroup as ENOENT giuseppe/libpod
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@giuseppe @edsantiago @vrothberg