On Mon, Apr 30, 2018 at 12:47:04PM +0300, Kirill A. Shutemov wrote: > On Wed, Apr 18, 2018 at 11:49:09AM -0700, Matthew Wilcox wrote: > > From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> > > > > This gives us five words of space in a single union in struct page. > > The compound_mapcount moves position (from offset 24 to offset 20) > > on 64-bit systems, but that does not seem likely to cause any trouble. > > Yeah, it should be fine. > > Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> I was wondering if it might make sense to make compound_mapcount an atomic_long_t. It'd guarantee no overflow, and prevent the location from moving.
