lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 21 Aug 2018 08:11:44 +0300 From: Konstantin Khlebnikov <koct9i@...il.com> To: Matthew Wilcox <willy@...radead.org> Cc: Roman Gushchin <guro@...com>, linux-mm@...ck.org, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, kernel-team@...com, Andrew Morton <akpm@...ux-foundation.org>, Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>, Tejun Heo <tj@...nel.org>, Rik van Riel <riel@...riel.com> Subject: Re: [PATCH RFC] mm: don't miss the last page because of round-off error On Sat, Aug 18, 2018 at 4:22 AM, Matthew Wilcox <willy@...radead.org> 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. There is macro DIV_ROUND_UP in kernel.h
Powered by blists - more mailing lists