
Automatic merge from submit-queue (batch tested with PRs 63830, 63579, 64173). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>. Fix iSCSI and RBD UnmountDevice with mount containers. Google's [configure-helper.sh](https://github.com/kubernetes/kubernetes/blob/master/cluster/gce/gci/configure-helper.sh) script bind-mounts `/var/lib/kubelet` somewhere into `/home/kubernetes` and thus every mount that Kubernetes does is visible **twice** in `/proc/mounts`. iSCSI and RBD volume plugins should not rely on counting entries in `/proc/mounts` and unmount device when Kubernetes thinks it's unusued. Kubernetes tracks the mounts by itself and most of other volume plugins already rely on it safely. /sig storage Fixes #56704 (well, it does not fix it, but it makes Kubernetes working with double mounts) **Release note**: ```release-note NONE ``` @rootfs, PTAL