8000 fix(minvmd): replace raw-PID gvproxy signalling with pidfd by gominimal-aw-bot[bot] · Pull Request #555 · gominimal/minimal · GitHub
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fix(minvmd): replace raw-PID gvproxy signalling with pidfd - #555

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norrietaylor merged 2 commits into
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sdd/550-gvproxy-pidfd-3343ddf2bf060369
Jun 24, 2026
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fix(minvmd): replace raw-PID gvproxy signalling with pidfd#555
norrietaylor merged 2 commits into
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sdd/550-gvproxy-pidfd-3343ddf2bf060369

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@gominimal-aw-bot
@gominimal-aw-bot gominimal-aw-bot Bot commented Jun 24, 2026 •
edited by coderabbitai Bot
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[sdd-fastpath: tracking=550 tier=sonnet]

Fixes the independent-crash recycled-PID window in GvproxySwitch (#550).

What changed

Replaces raw-PID kill(2) on all three teardown paths with pidfd_send_signal(2) via libc::syscall(SYS_pidfd_send_signal, ...):

  • GvproxySwitch::stop()
  • GvproxySwitch::Drop
  • PtaskAttachment::Drop

pidfd_open(2) is called immediately after the child PID is extracted in supervise(), before the supervision task is spawned. The Arc<OwnedFd> is shared with every PtaskAttachment so all teardown paths use the same pidfd. A pidfd is bound to the exact process instance — pidfd_send_signal returns ESRCH after the process exits, never resolving to a recycled PID.

signal_child (raw kill(2)) is retained under #[cfg(not(target_os = "linux"))] for macOS development builds.

Proof artifacts

Test — cargo test -p minvmd net::tests::pidfd_signal_to_reaped_child_returns_esrch:

test net::tests::pidfd_signal_to_reaped_child_returns_esrch ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 71 filtered out; finished in 0.00s

File — grep -q 'pidfd' crates/minvmd/src/net.rs:
Returns exit code 0 (pidfd is present in net.rs).

All 19 net tests (including existing teardown tests):

test net::tests::drop_sigkills_supervised_child_without_blocking ... ok
test net::tests::last_ptask_detach_terminates_switch ... ok
test net::tests::pidfd_signal_to_reaped_child_returns_esrch ... ok
test net::tests::stop_terminates_supervised_child ... ok
test net::tests::unexpected_exit_fires_notify ... ok
test result: ok. 19 passed; 0 failed; 0 ignored; 0 measured; 53 filtered out; finished in 0.02s

Merging this pull request advances the tracking issue from sdd:in-progress to sdd:done; a human does the final close.

Generated by sdd-execute (sonnet tier) · ◷

Summary by CodeRabbit

Release Notes

  • Bug Fixes

    • Improved Linux process supervision and teardown reliability by using safer, recycle-resistant signaling to ensure supervised services terminate and clean up correctly.

  • Tests

    • Added Linux-only coverage to confirm correct pidfd signaling behavior, including expected failure after a process has been reaped.

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@coderabbitai coderabbitai[bot] coderabbitai[bot] left review comments
@norrietaylor norrietaylor norrietaylor approved these changes

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