VSIE_PAGE_IN_USE
if (test_bit(VSIE_PAGE_IN_USE, &vsie_page->flags))
return !test_and_set_bit(VSIE_PAGE_IN_USE, &vsie_page->flags);
clear_bit(VSIE_PAGE_IN_USE, &vsie_page->flags);
__set_bit(VSIE_PAGE_IN_USE, &vsie_page->flags);