Should page->count ever be -1?

From: Timur Tabi (ttabi@interactivesi.com)
Date: Wed Jan 03 2001 - 16:07:03 EST

I'm experiencing some kind of memory leaks playing with ioremap and iounmap,
and I've narrowed down the problem to iounmap refusing to unmap the memory that
I just mapped. The line of code in question is

        if (!PageReserved(page) && atomic_dec_and_test(&page->count)) {

from page_alloc.c (this is 2.2.18pre15). It appears that page->count is
already zero when this code is executed, and after it's executed, page->count
becomes -1 (or more accurately, 0xFFFFFFFF). Is this acceptable, or is it an
error condition? 

-- 
Timur Tabi - ttabi@interactivesi.com
Interactive Silicon - http://www.interactivesi.com

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