Merge r285939-285941,285943,286004 from stable/10:

• Protect against ioctl() vs ioctl() races.
• Always lock hash row of a source node when updating its 'states' counter. [1]
• Don't dereference NULL is pf_get_mtag() fails. [2]
• During module unload drop locks before destroying UMA zone.

PR: 182401 [1]
PR: 200222 [2]
Approved by: re (gjb)