-> got 1000 pages
-> unpin 0..100 OK ret 0
-> unpin 200..300 OK ret 0
-> unpin 400..500 OK ret 0
-> unpin 600..700 OK ret 0
-> unpin 800..900 OK ret 0
-> pin 0..100 OK ret 1
-> pin 100..200 OK ret 0
-> pin 200..300 OK ret 1
-> pin 300..400 OK ret 0
-> pin 400..500 OK ret 1
-> pin 500..600 OK ret 0
-> pin 600..700 OK ret 1
-> pin 700..800 OK ret 0
-> pin 800..900 OK ret 1
-> pin 900..1000 OK ret 0