{"record":{"id":"b453c6c5a8931cf3","repo":"xai-org/grok-build","slug":"could-not-find-cgroupv2-entry-in-proc-self-cgroup","errorCode":null,"errorMessage":"Could not find cgroupv2 entry in /proc/self/cgroup","messagePattern":"Could not find cgroupv2 entry in /proc/self/cgroup","errorType":"exception","errorClass":"std::io::Error","httpStatus":null,"severity":"error","filePath":"crates/codegen/xai-grok-tools/src/computer/local/cgroup.rs","lineNumber":173,"sourceCode":"                break;\n            }\n            guard.clear_ready();\n            Ok(())\n        }\n    }\n\n    // ── Cgroup helpers ───────────────────────────────────────────────────\n\n    /// Read `/proc/self/cgroup` to find our own cgroup path (cgroup v2 unified).\n    fn read_self_cgroup() -> std::io::Result<String> {\n        let contents = std::fs::read_to_string(\"/proc/self/cgroup\")?;\n        // In cgroupv2 unified hierarchy, the line is \"0::<path>\"\n        for line in contents.lines() {\n            if let Some(rest) = line.strip_prefix(\"0::\") {\n                return Ok(rest.to_owned());\n            }\n        }\n        Err(std::io::Error::new(\n            std::io::ErrorKind::NotFound,\n            \"Could not find cgroupv2 entry in /proc/self/cgroup\",\n        ))\n    }\n\n    /// Parse the `high <N>` counter from `memory.events` contents.\n    fn parse_memory_events_high(contents: &str) -> Option<u64> {\n        for line in contents.lines() {\n            if let Some(value) = line.strip_prefix(\"high \") {\n                return value.trim().parse::<u64>().ok();\n            }\n        }\n        None\n    }\n\n    // ── CgroupHandle ─────────────────────────────────────────────────────\n\n    /// Owns the lifecycle of a child cgroup directory.","sourceCodeStart":155,"sourceCodeEnd":191,"githubUrl":"https://github.com/xai-org/grok-build/blob/bc7f02eddd3d84085849dc19ed216f11c23b0571/crates/codegen/xai-grok-tools/src/computer/local/cgroup.rs#L155-L191","documentation":"read_self_cgroup parses /proc/self/cgroup looking for a cgroupv2 unified-hierarchy line with the \"0::\" prefix. If no such line is found (the file exists but contains only cgroup v1 hierarchy entries, or none), the function returns io::ErrorKind::NotFound. It is used by create to locate the process's cgroup path for resource control.","triggerScenarios":"Calling create() on a host running cgroup v1 (hybrid/legacy hierarchy) where /proc/self/cgroup has lines like \"12:pids:/...\" but no \"0::<path>\" line; running inside containers/namespaces where the cgroup file is masked or empty.","commonSituations":"Older Linux distributions (pre-systemd v2 adoption, e.g. CentOS 7) using cgroup v1; Docker/Kubernetes setups with cgroup v1 driver; WSL1 or environments without cgroupv2 unified hierarchy; /proc not mounted properly in a chroot.","solutions":["Migrate the host to cgroup v2 unified hierarchy (boot with systemd.unified_cgroup_hierarchy=1 or upgrade the distro).","Verify /proc/self/cgroup contains a \"0::\" line: cat /proc/self/cgroup.","Guard the create() call and fall back to running without cgroup-based limits when NotFound is returned.","Check container runtime cgroup driver configuration (switch to systemd/cgroup v2 driver)."],"exampleFix":"// before\nlet cgroup = Cgroup::create(...)?;\n// after\nlet cgroup = match Cgroup::create(...) {\n    Ok(c) => Some(c),\n    Err(e) if e.kind() == std::io::ErrorKind::NotFound => {\n        tracing::warn!(\"cgroupv2 unavailable, running without cgroup limits\");\n        None\n    }\n    Err(e) => return Err(e),\n};","handlingStrategy":"fallback","validationCode":"let has_v2 = std::fs::read_to_string(\"/proc/self/cgroup\")\n    .map(|c| c.lines().any(|l| l.starts_with(\"0::\")))\n    .unwrap_or(false);\nif !has_v2 { /* skip cgroup setup or abort with clear config error */ }","typeGuard":null,"tryCatchPattern":"match Cgroup::create(...) {\n    Ok(c) => Some(c),\n    Err(e) if e.kind() == std::io::ErrorKind::NotFound => {\n        tracing::warn!(\"no cgroupv2 entry; limits disabled\");\n        None\n    }\n    Err(e) => return Err(e.into()),\n}","preventionTips":["Verify cgroup v2 unified hierarchy at service startup (stat /sys/fs/cgroup/cgroup.controllers).","Configure container runtimes to use the cgroup v2 driver.","Document the cgroup v2 requirement and fail fast with a clear message when missing.","Test on hosts with both cgroup v1 and v2."],"tags":["linux","cgroup","environment","not-found"],"backgroundTag":"cgroupv2-unavailable","analyzedSha":"bc7f02eddd3d84085849dc19ed216f11c23b0571","analyzedAt":"2026-08-31T04:59:42.031Z","schemaVersion":2},"datasetVersion":"2026-08-31T09:17:48.483Z"}