windbg !gcroot <address> returns no roots

Question

What does it mean if !gcroot returns an empty thread list?

0:000> !gcroot 0000000010817c50 
Note: Roots found on stacks may be false positives. Run "!help gcroot" for
more info.
Scan Thread 2 OSTHread 15a4
Scan Thread 10 OSTHread 1db4
Scan Thread 11 OSTHread 147c
Scan Thread 12 OSTHread 15d4
Scan Thread 14 OSTHread 9dc
Scan Thread 15 OSTHread 12a4
Scan Thread 21 OSTHread 18c4
Scan Thread 23 OSTHread 1260
Scan Thread 24 OSTHread 16c8
Scan Thread 25 OSTHread bd4
Scan Thread 26 OSTHread de8

I have a LOT of entries when doing !dumpheap -type System.String, but most of them return nothing as the example above.

Answer 1

The are no roots for these objects and when the GC runs it will collect the objects.