A constrained cgroup encloses eligible processes, while an unrelated host process remains outside. Host-wide free memory cannot determine a cgroup OOM diagnosis.

OOM investigation starts with the allocation scope

Linux can invoke an out-of-memory killer when an allocation cannot be satisfied within its relevant constraints after appropriate reclaim attempts. It is a last-resort recovery mechanism, not an application priority scheduler. Some allocations fail without a kill, and configuration can instead lead to panic behavior. Start an investigation by identifying the allocation scope and recorded event, rather than declaring that the machine must have exhausted every byte of RAM. ...

October 26, 2026 · 5 min · XB Field Notes