Qestion about page->_count and page reclaim

[Li Haifeng]

Hi, all in kernel.

The page->_count is the page frame's usage count. When page is
allocated, the page->_cout will be set 1.

After be allocated from buddy system, the page will be used by
process.  get_page and put_page/put_page_testzero will used in pairs.
is it right?

When the page is reclaimed to buddy system, the page->_count should be
0. However, Because the initialization of page->_count is 1,
get_page() and put_page() is called in pairs, I coufused how
page->_count will be 0?

Thanks.