Merge pull request kubernetes#46016 from kokhang/rbd-modprobe

Automatic merge from submit-queue (batch tested with PRs 47084, 46016, 46372)

Warn, instead of failing, if 'modprobe rbd' fails

Modprobe is a kernel operation that should only be done once to load the
RBD module. The admin could've done this on the Kubernetes nodes. The
RBD plugin can still try to load the module but it shouldnt fail the
workflow if it doesnt succeed.

Partially addresses kubernetes#45190

pkg/volume/rbd/rbd_util.go

@@ -264,7 +264,7 @@ func (util *RBDUtil) AttachDisk(b rbdMounter) error {
 		// modprobe
 		_, err = b.plugin.execCommand("modprobe", []string{"rbd"})
 		if err != nil {
-			return fmt.Errorf("rbd: failed to modprobe rbd error:%v", err)
+			glog.Warningf("rbd: failed to load rbd kernel module:%v", err)
 		}
 
 		// fence off other mappers