dockerd likely remains stuck in a socket churn loop. A diagnosis report and patch proposal were created locally.
Published session
Prompt
## Plan Pass
You are planning a fixer patch before any edits happen.
Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. The original pre-edit snapshot is available at `./source` if you need to inspect it. For interpreter processes, plan from the script/application entrypoint evidence first and include the runtime only as a second investigation target unless the evidence proves a runtime bug.
Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `docker.io` upstream patch, not just a Debian-local workaround. Inspect the relevant code, nearby callers, project contribution docs, and local helper/compat APIs, but do not edit files in this pass.
Return a short markdown plan with these exact sections:
## Problem
## Evidence Confidence
## Proposed Subject
## Patch Plan
## Risks
## Validation
Classify `## Evidence Confidence` as exactly one of `reproduced`, `observed`, or `inferred`. Use `inferred` only for a no-patch diagnosis/report plan unless you can name the extra evidence you will collect before editing; inferred source patches are blocked by Fixer because they are not pull-request-ready. For `observed` source-patch plans, plan to say in the final `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. The plan must explain how the proposed code change addresses the observed issue evidence, call out any prior Fixer patch that should be improved or replaced, reject awkward control flow such as avoidable `goto` if there is a cleaner bounded alternative, name any local helper APIs or maintainer conventions the patch should follow, and keep the intended maintainer-facing explanation clear enough that someone unfamiliar with the local complaint wording can still follow the fix. In `## Validation`, name the reproducible configure/build/test entrypoint you will try from the workspace root before any focused leaf compile or smoke check, and include one bounded independent reproduction attempt for the collected failure signal when it is safe and cheap. Do not plan to claim `reproduced` unless that reproduction command or test can actually show the failure.
## Patch Pass
You are working on a bounded fixer proposal.
Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Produce the smallest reasonable patch for the target repository, keep the change upstreamable, prefer the clearest control flow available, and do not keep avoidable `goto` when a simpler structure would read better. Before introducing new file, process, allocation, locking, networking, or platform APIs, inspect nearby code and project contribution docs for existing helpers or compatibility wrappers and use those local patterns unless you can explain why they do not fit. Validate from a reproducible workspace-root entrypoint before falling back to focused leaf commands; if a build or test cannot run, report the exact command, the exact blocker, and any narrower check you ran instead. During validation, also try one bounded independent reproduction of the collected failure signal when it is safe and cheap, such as a failing test, smoke command, perf/strace comparison, or before/after runtime check. Only use `reproduced` if that command or test actually reproduced the failure; otherwise keep `observed` and report the reproduction blocker. The final explanation must connect the observed issue evidence to the actual code change, not just paraphrase the diff. Write like a maintainer is going to read the patch mail cold: explain the bug in plain language, define subsystem-specific jargon the first time you need it, and make the causal story obvious. Explicitly classify evidence confidence as `reproduced`, `observed`, or `inferred`: `reproduced` means you reproduced the failure locally; `observed` means Fixer has direct crash/log/trace evidence but you did not independently reproduce it; `inferred` means the source patch is not pull-request-ready, so do not leave a source diff unless you first gather stronger observed/reproduced evidence; otherwise return a no-patch diagnosis/report. For any source-changing `observed` patch, say explicitly in `## Issue Connection` that the failure was observed by Fixer and not independently reproduced. If you introduce non-obvious state translation, index remapping, or backend split logic, add a short source comment that explains the invariant being preserved.
Start by explaining the likely root cause from the collected perf, strace, and /proc evidence. If you cannot land a safe patch, leave a diagnosis that is strong enough for an upstream bug report.
Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `docker.io` upstream patch, not just a Debian-local workaround.
Keep the change narrowly scoped and summarize validation clearly.
In every authoring pass, your final response must start with `Subject: <single-line git commit subject>` and then include these markdown sections exactly:
## Commit Message
A short upstream-friendly explanation of what changed and why. Write it in plain language that a maintainer can follow without local complaint context. If you use subsystem jargon, define it immediately.
## Evidence Confidence
Exactly one word: `reproduced`, `observed`, or `inferred`. Use `reproduced` only when you reproduced the failure locally with a command or test, and include that command/test in `## Validation`. Use `observed` when Fixer has direct crash/log/trace evidence but you did not independently reproduce it. If `## Git Add Paths` lists source files for an `observed` patch, `## Issue Connection` must explicitly say the failure was observed by Fixer and not independently reproduced. Use `inferred` for profiler/strace/indirect evidence; inferred responses may be no-patch diagnoses or reports, but inferred source patches are not pull-request-ready until stronger evidence is gathered.
## Issue Connection
Write this as maintainer-facing patch mail, not as local Fixer notes. Cover four things explicitly in readable sentences: the user-visible symptom or the exact collected signal, the code-level cause or the cautious inference from evidence, the specific change you made, and the expected effect. Do not invent a reproducer, command line, crash, or user-visible failure that is not present in the evidence bundle. If the evidence is direct-but-not-reproduced, say it was observed by Fixer and not independently reproduced. If the evidence is indirect and you did not gather stronger evidence, do not leave a source diff; write a no-patch diagnosis/report instead. Include an explicit effect sentence such as `The expected effect is ...`, `This should reduce ...`, or `This prevents ...` for source patches. If the logic is non-obvious in code, mention that you added a short explanatory comment.
## Git Add Paths
List the repo-relative paths that belong in the final patch, one per line. Use `None` only when you intentionally made no source changes. Include intentionally new files, and do not list generated build artifacts.
## Validation
List the checks you ran, or say clearly that you could not run them. Include the independent reproduction command/test and result when `## Evidence Confidence` is `reproduced`; if reproduction was attempted but blocked, name the exact blocker and keep confidence at `observed` or `inferred`.
Before editing, read the plan at `./plan-output.txt` and follow it unless the code proves part of it wrong. If you change course, say so explicitly in the final write-up instead of silently drifting from the plan.
## Review Pass 1
You are reviewing a freshly generated fixer patch.
Read the evidence bundle at `./evidence.json`. The prepared workspace is `./workspace` and it was acquired via `debian-source`. Review the first patch pass. The original pre-edit snapshot is available at `./source` for diffing.
Upstream-style expectation: before planning or editing, check for contribution/style docs (`CONTRIBUTING`, `HACKING`, `README-hacking`, `README.md`, `docs/`, `dev-docs/`) and scan the touched subsystem for local helpers. If the project has wrappers for file IO, path-relative IO, process spawning, memory allocation, logging, locking, or platform compatibility, prefer those wrappers over generic libc/std APIs. Do not invent a reproducer or user-visible failure that is not in the evidence bundle; if the evidence is profiler-only or indirect, describe it as a targeted mitigation or stop with a diagnosis instead of presenting a speculative patch as a confirmed bug fix. In the plan and final validation, name any such helper, convention, or evidence limit you found, or say that no relevant local helper was found. Treat this as a `docker.io` upstream patch, not just a Debian-local workaround. The latest author response is at `./patch-output.txt`. Inspect the current code and changed paths like a strict code reviewer. Focus on correctness, regressions, maintainability, awkward control flow such as avoidable `goto`, missing validation, weak or non-gittable commit message text, and explanations that fail to connect the observed issue evidence to the code change. Also review the maintainer experience: the patch mail should be easy to accept upstream, the user-visible bug should be explained in plain language, subsystem-specific jargon should be defined when first used, and any non-obvious state translation or index remapping in code should have a short explanatory comment. Reject patches that omit `## Evidence Confidence`, use anything other than `reproduced`, `observed`, or `inferred`, or sound more certain than that evidence level allows. Reject patches that claim `reproduced` unless `## Validation` names the concrete reproduction command or test and its result. Reject patches that invent a reproducer, command line, crash, or user-visible failure not present in the evidence bundle; indirect profiler or strace evidence may justify a cautious mitigation, but the author must say it is indirect instead of presenting it as a confirmed upstream bug. Reject patches that introduce generic libc/std APIs when nearby code or project docs provide a local compat/helper API for the same job, unless the author explicitly justifies the exception. Reject validation that only reports a leaf object/syntax build when a project-level configure/build/test entrypoint exists and was not attempted; if a full build cannot run, the author must show the exact failed command and blocker.
Do not apply code changes in this pass.
Return a short markdown review report. The first non-empty line must be exactly one of:
RESULT: ok
RESULT: fix-needed
If you choose `RESULT: fix-needed`, add a `## Findings` section with concrete, actionable items.
Response
## Plan Pass
## Problem
Fixer observed `/usr/sbin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock` with many sleeping threads in futex waits, low CPU, and an indirect `socket-churn` classification. The hottest sampled symbol was kernel-side `bpf_lsm_file_permission`, and the implicated package was the kernel, not a symbolized Moby frame. The raw strace path named in the evidence bundle is not present in this workspace, so there is not enough source-level evidence to justify an upstream Moby patch yet.
## Evidence Confidence
inferred
## Proposed Subject
No source patch yet: collect symbolized dockerd/containerd evidence before proposing a Moby change.
## Patch Plan
Do not edit files in this pass. I inspected the dockerd entrypoint first (`engine/cmd/dockerd`) and then the containerd-facing runtime path (`engine/daemon/daemon.go`, `engine/libcontainerd/remote/client.go`). A plausible area is the libcontainerd event stream reconnect path, but the current evidence does not prove it is responsible for the observed futex/socket profile.
Before any patch, collect the missing full raw artifacts or equivalent fresh data: symbolized goroutine dump/backtrace, full `strace -f` with socket/connect/futex/waitid counts, fd targets, and containerd availability/logs. If that evidence points to `processEventStream` or `waitServe`, design a small upstream-style change using existing conventions: `context` cancellation, `containerd/log` via `log.G(ctx)`, existing gRPC/containerd dial options, and a bounded retry/backoff loop. Avoid awkward control flow such as an avoidable `goto`; prefer a clear loop with explicit exit on context cancellation.
No prior Fixer patch for `90267`, futex/socket churn, or `bpf_lsm_file_permission` was found in the workspace or Debian patch stack.
## Risks
A source patch from the current bundle would be speculative: the process was sleeping, CPU was only 0.1%, the hot path is kernel-side, and the evidence lacks symbolized Go frames or a concrete user-visible failure.
Changing dockerd/containerd reconnect behavior without confirmed causality could regress daemon recovery after containerd restarts.
## Validation
Start with the reproducible project entrypoints from the workspace root: `dpkg-buildpackage -us -uc -b` for the Debian package path, or at minimum `cd engine && make test-unit` per upstream Moby testing docs before any focused package test.
For a bounded independent reproduction attempt, build/run a local dockerd under `timeout` with a controlled temporary data root and containerd socket condition, capturing `strace -f -e trace=futex,connect,accept,waitid`. Only claim reproduction if it shows the same repeated futex/socket signal; otherwise report it as not independently reproduced.
## Patch Pass
Subject: diagnose dockerd futex profile without source change
## Commit Message
No source change. The collected profile points to a sleeping dockerd process with many Go runtime futex waits, but it does not identify a Moby code path that is safe to change upstream.
## Evidence Confidence
inferred
## Issue Connection
The collected signal is a 3-second perf profile and 5-second strace summary for `/usr/sbin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock`: dockerd had 185 threads, process state `S (sleeping)`, about 0.1% CPU, repeated `FUTEX_WAIT_PRIVATE` entries, a few `waitid(P_PIDFD, ...)` entries, and a kernel hot symbol `bpf_lsm_file_permission`. The likely root cause from the `/proc`, perf, and strace evidence is not a confirmed busy loop in Moby; it is a mostly parked Go daemon whose threads are blocked in futex waits, with the profiler attributing sampled kernel time to an LSM/BPF permission hook.
I followed the saved plan and did not land a source patch. I inspected the dockerd entrypoint first, then the containerd-facing daemon code. The closest plausible area is `engine/libcontainerd/remote/client.go`, where the libcontainerd event stream subscribes to containerd task events and waits for containerd readiness before resubscribing. That code already uses the local conventions I would use for a real patch: `context` cancellation, `containerd/log` via `log.G(ctx)`, and containerd/gRPC dial helpers such as `dialer.ContextDialer`. The evidence does not connect the observed futex waits or kernel `bpf_lsm_file_permission` samples to that path, so changing it would be speculative.
The expected effect of this no-patch result is to avoid an upstream-unready change and preserve a useful upstream bug-report diagnosis: the next evidence needed is a symbolized goroutine dump or backtrace, complete strace/fd targets, and containerd logs around the same sample window.
## Git Add Paths
None
## Validation
`timeout 120s dpkg-buildpackage -us -uc -b` from the workspace root failed before build because `dpkg-checkbuilddeps` reported unmet build dependencies, starting with `dh-golang`, `golang-any`, `go-md2man`, and many Go library `-dev` packages.
`cd engine && go test ./libcontainerd/remote` also failed: Go could not resolve required modules with import lookup disabled by `-mod=readonly`, and the environment also lacked `GOCACHE`/`HOME`.
Bounded independent reproduction attempt: `timeout 10s strace -f -e trace=futex,connect,accept,accept4,waitid /usr/sbin/dockerd --validate` did not run because ptrace is blocked in this sandbox: `PTRACE_TRACEME: Operation not permitted` and `ptrace(PTRACE_SEIZE, 7): Operation not permitted`.
`git diff --stat` is empty; no source files were changed.
## Review Pass 1
RESULT: ok
No source diff is present against the workspace or original snapshot, which is appropriate for the `inferred` evidence level. The author response includes the required sections, does not overclaim reproduction, attempts the workspace-root build entrypoint, reports exact blockers, and gives a bounded reproduction attempt that was blocked by ptrace permissions.
The diagnosis is consistent with the evidence: low-CPU sleeping dockerd, futex waits, and kernel-side `bpf_lsm_file_permission` samples do not justify an upstream Moby source patch without stronger symbolized evidence.