Forrest McDaniel leaves us with a head injury:
Now, I may not be an expert, but sqlmin!Spinlock sounds like…a spinlock. This thread has been spinning for over a minute, never returning to a waiting state, because something else is holding the spinlock resource.
Thankfully, helpful friends alerted me to a blog that revealed the value of an acquired spinlock “is the Windows thread ID of the owner.” Meaning I might be able to find the cause.
Read the whole thing.