On Tue, Aug 21, 2018 at 08:11:44AM +0300, Konstantin Khlebnikov wrote: > On Sat, Aug 18, 2018 at 4:22 AM, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > On Fri, Aug 17, 2018 at 04:18:34PM -0700, Roman Gushchin wrote: > >> - scan = div64_u64(scan * fraction[file], > >> - denominator); > >> + if (scan > 1) > >> + scan = div64_u64(scan * fraction[file], > >> + denominator); > > > > Wouldn't we be better off doing a div_round_up? ie: > > > > scan = div64_u64(scan * fraction[file] + denominator - 1, denominator); > > > > although i'd rather hide that in a new macro in math64.h than opencode it > > here. > > All numbers here should be up to nr_pages * 200 and fit into unsigned long. > I see no reason for u64. If they overflow then u64 wouldn't help either. It is nr_pages * 200 * recent_scanned, where recent_scanned can be up to four times of what's on the LRUs. That can overflow a u32 with even small amounts of memory.
