On Thu 20-12-18 00:39:18, Oscar Salvador wrote: > On Wed, Dec 19, 2018 at 02:25:28PM +0000, Wei Yang wrote: > > >- iter = round_up(iter + 1, 1<<compound_order(page)) - 1; > > >+ skip_pages = (1 << compound_order(head)) - (page - head); > > >+ iter = round_up(iter + 1, skip_pages) - 1; > > > > The comment of round_up says round up to next specified power of 2. And > > second parameter must be a power of 2. > > > > Look skip_pages not satisfy this. Yes this is true but the resulting numbers should be correct even for skips that are not power of 2 AFAIC. Or do you have any counter example? > > At least alloc_gigantic_page() looks for 1GB range, aligned to that. > But I see that in alloc_contig_range(), the boundaries can differ. > > Anyway, unless I am missing something, I think that we could just > get rid of the round_up() and do something like: > > <-- > skip_pages = (1 << compound_order(head)) - (page - head); > iter = skip_pages - 1; > -- > > which looks more simple IMHO. Agreed! -- Michal Hocko SUSE Labs
