Francois reported that VMware balloon gets stuck after a balloon reset,
when the VMCI doorbell is removed. A similar error can occur when the
balloon driver is removed with the following splat:

[ 1088.622000] INFO: task modprobe:3565 blocked for more than 120 seconds.
[ 1088.622035]       Tainted: G        W         5.2.0 #4
[ 1088.622087] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1088.622205] modprobe        D    0  3565   1450 0x00000000
[ 1088.622210] Call Trace:
[ 1088.622246]  __schedule+0x2a8/0x690
[ 1088.622248]  schedule+0x2d/0x90
[ 1088.622250]  schedule_timeout+0x1d3/0x2f0
[ 1088.622252]  wait_for_completion+0xba/0x140
[ 1088.622320]  ? wake_up_q+0x80/0x80
[ 1088.622370]  vmci_resource_remove+0xb9/0xc0 [vmw_vmci]
[ 1088.622373]  vmci_doorbell_destroy+0x9e/0xd0 [vmw_vmci]
[ 1088.622379]  vmballoon_vmci_cleanup+0x6e/0xf0 [vmw_balloon]
[ 1088.622381]  vmballoon_exit+0x18/0xcc8 [vmw_balloon]
[ 1088.622394]  __x64...