NULLB_PAGE_LOCK
__clear_bit(NULLB_PAGE_LOCK, c_page->bitmap);
if (test_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap))
__set_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap);
if (test_bit(NULLB_PAGE_LOCK, t_page->bitmap))