On Fri, Jan 10, 2020 at 02:15:26PM +0100, David Hildenbrand wrote: > On 08.01.20 15:40, Michal Hocko wrote: > > On Mon 30-12-19 12:38:28, Kirill A. Shutemov wrote: > >> memmap_init_zone() can be called on the ranges with holes during the > >> boot. It will skip any non-valid PFNs one-by-one. It works fine as long > >> as holes are not too big. > >> > >> But huge holes in the memory map causes a problem. It takes over 20 > >> seconds to walk 32TiB hole. x86-64 with 5-level paging allows for much > >> larger holes in the memory map which would practically hang the system. > >> > >> Deferred struct page init doesn't help here. It only works on the > >> present ranges. > >> > >> Skipping non-present sections would fix the issue. > > > > Makes sense to me. > > > >> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > > > > That pfn inc back and forth is quite ugly TBH but whatever. > > Indeed, can we please rewrite the loop to fix that? Any suggestions? I don't see an obvious way to not break readablity in another place. -- Kirill A. Shutemov
