I tested a similar storage configuration on an external disk connected to the same computer; doing an LVM snapshot inside LUKS behaves correctly on an external disk.
Thus, this LVM glitch is probably limited to taking a snapshot of a root filesystem that is in LUKS.
Also note that nothing is being logged into the syslog or dmesg. The hang instantly stops all IO to the root filesystem.
I tested a similar storage configuration on an external disk connected to the same computer; doing an LVM snapshot inside LUKS behaves correctly on an external disk.
Thus, this LVM glitch is probably limited to taking a snapshot of a root filesystem that is in LUKS.
Also note that nothing is being logged into the syslog or dmesg. The hang instantly stops all IO to the root filesystem.