On Tue, Jan 28, 2020 at 07:24:10PM -0800, John Hubbard wrote: > When debugging a problem that involves compound pages, it is extremely > helpful if dump_page() reports not only the page->_refcount, but also > the refcount of the head page of the compound page. That's because the > head page collects refcounts for the entire compound page. > > Therefore, enhance dump_page() so as to print out the refcount of the > head page of a compound page. > > This approach (printing information about a struct page that is not the > struct page that was passed into dump_page()) has a precedent: > compound_mapcount is already being printed. refcount on a tail must always be 0. I think we should only print it when it is non-zero, emphasizing this fact with a standalone message. -- Kirill A. Shutemov
