I have a ten year business M type but the M type was put near the back of my passport.

I'm on the last page of my visa's with stamps but I still have a few empty pages in my passport books but they pages before the M type. An example would like my chinese business M type is on page 24 I have stamps on pages 25, 26, and 27 ( 27 is the last page). But pages 20 to 23 are empty but they are before the M type. When page 27 is filled up would the customs official put stamps on pages preceding the visa like on page 22? Or would I have to get a whole new passport book because I'm an American and the US Department of State no longer allow additional pages to be added to your passport book. I'm mostly just curious.