Stop and delete could fail with device-mapper busy errors when the persisted Firecracker PID was stale or the kernel needed longer to release the root snapshot.
Rediscover a live Firecracker process by API socket during cleanup, kill and wait on that PID instead of trusting only the stored runtime PID, and extend dm snapshot removal retries for transient busy handles.
Add daemon regressions for stale-runtime reconcile, rediscovered process cleanup, and repeated busy dm removal. Validate with go test ./..., make build, and a live ./banger vm stop debug-ssh run that now exits cleanly.
Thales Maciel
7b7f7e676c