Snapshot changed state to invalid and should be removed.

Issue

• LVM snapshot status became invalid.
• "Snapshot xxx changed state to: Invalid and should be removed" displayed in /var/log/messages.

messages:Dec 18 14:29:52 abc123 kernel: device-mapper: snapshots: Invalidating snapshot: Unable to allocate exception.
messages:Dec 18 14:29:52 abc123 kernel: device-mapper: snapshots: Invalidating snapshot: Unable to allocate exception.
messages:Dec 18 14:29:52 abc123 lvm[1894]: WARNING: Snapshot rootvg-snap changed state to: Invalid and should be removed.
messages:Dec 18 14:29:52 abc123 lvm[1894]: WARNING: Snapshot rootvg-ssnap changed state to: Invalid and should be removed.

• From lvs output, "I" flag shows in volume attributes.

 ssnap    rootvg        swi-I-s---  600.00m      optvol  100.00                                          /dev/sda2(12349
                            ^
 ssnap    rootvg        swi-I-s---  600.00m      optvol  100.00                                          /dev/sda2(13474 
                            ^