Free vs Unused pages?

Bill Hawes (whawes@star.net)
Mon, 25 Aug 1997 10:11:07 -0400

While checking out some memory problems I noticed a discrepancy between
the number of free pages (on the free lists) and the number of unused
pages (page->count == 0), as reported by shift-scroll-lock. The number
of unused pages is always higher, typically by 80, sometimes by several
hundred.

As I'm not aware of any mechanism by which a page's count can go to 0
without freeing it, I suspect that this may indicate memory leaks caused
by doing an atomic_dec(&page->count) instead of __free_page(page). So
my question is: are there legitimate mechanisms for dropping the page
count to 0, or can I assume that there's a memory leak to be tracked
down?

Regards,
Bill