On Fri, Dec 14, 2018 at 11:53:31AM -0800, Dave Hansen wrote: > On 12/14/18 11:48 AM, Matthew Wilcox wrote: > > I think we can do better than a proxy object with bit 0 set. I'd go > > for allocating something like this: > > > > struct dynamic_page { > > struct page; > > unsigned long vaddr; > > unsigned long pfn; > > ... > > }; > > > > and use a bit in struct page to indicate that this is a dynamic page. > > That might be fun. We'd just need a fast/static and slow/dynamic path > in page_to_pfn()/pfn_to_page(). We'd also need some kind of auxiliary > pfn-to-page structure since we could not fit that^ structure in vmemmap[]. Yes; working on the pfn-to-page structure right now as it happens ... in the meantime, an XArray for it probably wouldn't be _too_ bad.