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kubernetes-csi / csi-driver-smb

This driver allows Kubernetes to access SMB Server on both Linux and Windows nodes.

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Unmount fails with target is busy error

MattPOlson opened this issue · comments

commented

What happened:

Pods with volume mounts that use this driver are getting stuck in a terminating phase because the mounts are failing to unmount with this error:

Unmounting arguments: /var/lib/kubelet/pods/dfe8b984-0e62-4111-bc65-4720358a42a1/volumes/kubernetes.io~csi/pvc-ad1d4cda-a2a8-453a-a0af-069c72a68e44/mount
Output: umount: /var/lib/kubelet/pods/dfe8b984-0e62-4111-bc65-4720358a42a1/volumes/kubernetes.io~csi/pvc-ad1d4cda-a2a8-453a-a0af-069c72a68e44/mount: target is busy.
I0424 19:31:00.963678       1 utils.go:76] GRPC call: /csi.v1.Node/NodeUnpublishVolume
I0424 19:31:00.963704       1 utils.go:77] GRPC request: {"target_path":"/var/lib/kubelet/pods/52b576ca-4a27-4e12-b1f7-42f5bb3b4dc1/volumes/kubernetes.io~csi/pvc-d8160b18-54a3-4acd-884c-07cd7a47363c/mount","volume_id":"bdreporting.local/dev#pvc-d8160b18-54a3-4acd-884c-07cd7a47363c#"}
I0424 19:31:00.963756       1 nodeserver.go:100] NodeUnpublishVolume: unmounting volume bdreporting.local/dev#pvc-d8160b18-54a3-4acd-884c-07cd7a47363c# on /var/lib/kubelet/pods/52b576ca-4a27-4e12-b1f7-42f5bb3b4dc1/volumes/kubernetes.io~csi/pvc-d8160b18-54a3-4acd-884c-07cd7a47363c/mount
I0424 19:31:00.963788       1 mount_helper_common.go:93] unmounting "/var/lib/kubelet/pods/52b576ca-4a27-4e12-b1f7-42f5bb3b4dc1/volumes/kubernetes.io~csi/pvc-d8160b18-54a3-4acd-884c-07cd7a47363c/mount" (corruptedMount: false, mounterCanSkipMountPointChecks: true)
I0424 19:31:00.963797       1 mount_linux.go:362] Unmounting /var/lib/kubelet/pods/52b576ca-4a27-4e12-b1f7-42f5bb3b4dc1/volumes/kubernetes.io~csi/pvc-d8160b18-54a3-4acd-884c-07cd7a47363c/mount
E0424 19:31:00.971541       1 utils.go:81] GRPC error: rpc error: code = Internal desc = failed to unmount target "/var/lib/kubelet/pods/52b576ca-4a27-4e12-b1f7-42f5bb3b4dc1/volumes/kubernetes.io~csi/pvc-d8160b18-54a3-4acd-884c-07cd7a47363c/mount": unmount failed: exit status 32
Unmounting arguments: /var/lib/kubelet/pods/52b576ca-4a27-4e12-b1f7-42f5bb3b4dc1/volumes/kubernetes.io~csi/pvc-d8160b18-54a3-4acd-884c-07cd7a47363c/mount
Output: umount: /var/lib/kubelet/pods/52b576ca-4a27-4e12-b1f7-42f5bb3b4dc1/volumes/kubernetes.io~csi/pvc-d8160b18-54a3-4acd-884c-07cd7a47363c/mount: target is busy.

Also while this is occurring we see pods running on the same node experience mount failures with a "Broken Pipe" error, not sure if this is related out not.

What you expected to happen:

I expected the mounts to unmount with the pod is terminating.

How to reproduce it:

We have not been able to produce it reliably, is seems to happen with the disk the mounts are on are under heavy pressure.

Anything else we need to know?:

Environment:

  • CSI Driver version: v1.10.0
  • Kubernetes version (use kubectl version): 1.23
  • OS (e.g. from /etc/os-release): Fedora CoreOS 35
  • Kernel (e.g. uname -a): 5.18.5-100.fc35.x86_64
  • Install tools:
  • Others:
commented

It's expected for CSI driver to return "target is busy" error when files in file share are still open, to mitigate the state issue, force delete pod should work. And this also indicates that user should set preStop hook to terminiate the application when it receives SIGTERM signal from kubernetes, use force unmount is not the graceful way.

commented

Have you seen the issue where the mounts fail with this error? "Broken Pipe" It seems to occur around the same time.