[INFO] cloning repository https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/freifunk-luebeck/fastd-exporter-rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffreifunk-luebeck%2Ffastd-exporter-rust", kill_on_drop: false }` [INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffreifunk-luebeck%2Ffastd-exporter-rust'... [INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }` [INFO] [stdout] cb5c43042e1dac97b990e5b4960b47cebae04635 [INFO] checking freifunk-luebeck/fastd-exporter-rust against master#8387315ab3c26a57a1f53a90f188f0bc88514bca for pr-124605 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffreifunk-luebeck%2Ffastd-exporter-rust" "/workspace/builds/worker-4-tc1/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc1/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/freifunk-luebeck/fastd-exporter-rust on toolchain 8387315ab3c26a57a1f53a90f188f0bc88514bca [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+8387315ab3c26a57a1f53a90f188f0bc88514bca" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] finished tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] tweaked toml for git repo https://github.com/freifunk-luebeck/fastd-exporter-rust written to /workspace/builds/worker-4-tc1/source/Cargo.toml [INFO] crate git repo https://github.com/freifunk-luebeck/fastd-exporter-rust already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+8387315ab3c26a57a1f53a90f188f0bc88514bca" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] [stderr] Downloading crates ... [INFO] [stderr] Downloaded protobuf v2.8.0 [INFO] [stderr] Downloaded tiny_http v0.8.2 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+8387315ab3c26a57a1f53a90f188f0bc88514bca" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] e5799a3a0e12cb89b96440df4f1d3dd8da771b9889a69d5b1d0ec9e0f00dd2ab [INFO] running `Command { std: "docker" "start" "-a" "e5799a3a0e12cb89b96440df4f1d3dd8da771b9889a69d5b1d0ec9e0f00dd2ab", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "e5799a3a0e12cb89b96440df4f1d3dd8da771b9889a69d5b1d0ec9e0f00dd2ab", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "e5799a3a0e12cb89b96440df4f1d3dd8da771b9889a69d5b1d0ec9e0f00dd2ab", kill_on_drop: false }` [INFO] [stdout] e5799a3a0e12cb89b96440df4f1d3dd8da771b9889a69d5b1d0ec9e0f00dd2ab [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+8387315ab3c26a57a1f53a90f188f0bc88514bca" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] 71946fbe94012e74f76ba154e2fa4ca4e9e350bac6f3e85906652a20333c8d36 [INFO] running `Command { std: "docker" "start" "-a" "71946fbe94012e74f76ba154e2fa4ca4e9e350bac6f3e85906652a20333c8d36", kill_on_drop: false }` [INFO] [stderr] time="2024-05-18T21:37:02Z" level=error msg="error waiting for container: " [INFO] [stderr] Error response from daemon: mkdir /var/lib/docker/containers/71946fbe94012e74f76ba154e2fa4ca4e9e350bac6f3e85906652a20333c8d36/mounts: no space left on device [INFO] running `Command { std: "docker" "inspect" "71946fbe94012e74f76ba154e2fa4ca4e9e350bac6f3e85906652a20333c8d36", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "71946fbe94012e74f76ba154e2fa4ca4e9e350bac6f3e85906652a20333c8d36", kill_on_drop: false }` [INFO] [stdout] 71946fbe94012e74f76ba154e2fa4ca4e9e350bac6f3e85906652a20333c8d36 [INFO] checking freifunk-luebeck/fastd-exporter-rust against try#fcc50f77e1a14e407d895972348a0ff09eafc210 for pr-124605 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffreifunk-luebeck%2Ffastd-exporter-rust" "/workspace/builds/worker-4-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/freifunk-luebeck/fastd-exporter-rust on toolchain fcc50f77e1a14e407d895972348a0ff09eafc210 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] finished tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] tweaked toml for git repo https://github.com/freifunk-luebeck/fastd-exporter-rust written to /workspace/builds/worker-4-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/freifunk-luebeck/fastd-exporter-rust already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: mkdir /var/lib/docker/overlay2/94c4e40ff8b1bff6e33f4d7ce3547343f7095adfa6d1de6efdf06e25f8cceb1d/merged/opt/rustwide: no space left on device [INFO] checking freifunk-luebeck/fastd-exporter-rust against try#fcc50f77e1a14e407d895972348a0ff09eafc210 for pr-124605 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffreifunk-luebeck%2Ffastd-exporter-rust" "/workspace/builds/worker-4-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/freifunk-luebeck/fastd-exporter-rust on toolchain fcc50f77e1a14e407d895972348a0ff09eafc210 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] finished tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] tweaked toml for git repo https://github.com/freifunk-luebeck/fastd-exporter-rust written to /workspace/builds/worker-4-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/freifunk-luebeck/fastd-exporter-rust already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: mkdir /var/lib/docker/overlay2/4fbfae3ff082ae7e25df2fa486c438d3ee3dced65a2c38263576790c412122e6/merged/opt/rustwide: no space left on device [INFO] checking freifunk-luebeck/fastd-exporter-rust against try#fcc50f77e1a14e407d895972348a0ff09eafc210 for pr-124605 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffreifunk-luebeck%2Ffastd-exporter-rust" "/workspace/builds/worker-4-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/freifunk-luebeck/fastd-exporter-rust on toolchain fcc50f77e1a14e407d895972348a0ff09eafc210 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] finished tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] tweaked toml for git repo https://github.com/freifunk-luebeck/fastd-exporter-rust written to /workspace/builds/worker-4-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/freifunk-luebeck/fastd-exporter-rust already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: chown /var/lib/docker/overlay2/cfbaa4403f7f859214ee88ff47d5e16ea323e18de358331520e354ce703d27cd/work/work: no such file or directory [INFO] checking freifunk-luebeck/fastd-exporter-rust against try#fcc50f77e1a14e407d895972348a0ff09eafc210 for pr-124605 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffreifunk-luebeck%2Ffastd-exporter-rust" "/workspace/builds/worker-4-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/freifunk-luebeck/fastd-exporter-rust on toolchain fcc50f77e1a14e407d895972348a0ff09eafc210 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] finished tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] tweaked toml for git repo https://github.com/freifunk-luebeck/fastd-exporter-rust written to /workspace/builds/worker-4-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/freifunk-luebeck/fastd-exporter-rust already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: mkdir /var/lib/docker/overlay2/8b14d822cac3ff8f3a9fc6aca81f0012b9a11ceb7e2e15819da0bc70b6996229/merged: no space left on device [INFO] checking freifunk-luebeck/fastd-exporter-rust against try#fcc50f77e1a14e407d895972348a0ff09eafc210 for pr-124605 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffreifunk-luebeck%2Ffastd-exporter-rust" "/workspace/builds/worker-4-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc2/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/freifunk-luebeck/fastd-exporter-rust on toolchain fcc50f77e1a14e407d895972348a0ff09eafc210 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] finished tweaking git repo https://github.com/freifunk-luebeck/fastd-exporter-rust [INFO] tweaked toml for git repo https://github.com/freifunk-luebeck/fastd-exporter-rust written to /workspace/builds/worker-4-tc2/source/Cargo.toml [INFO] crate git repo https://github.com/freifunk-luebeck/fastd-exporter-rust already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+fcc50f77e1a14e407d895972348a0ff09eafc210" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stderr] Error response from daemon: mkdir /var/lib/docker/containers/0fcd65acaeba28a4ab9c2372d6a1f1a7580f79cdf44381b016b799be7d8d23ef/checkpoints: no space left on device [ERROR] this task or one of its parent failed! [ERROR] command failed: exit status: 1 [ERROR] note: run with `RUST_BACKTRACE=1` to display a backtrace.