Re: [PATCH v5] mm,writeback: fix divide by zero in pos_ratio_polynom

Andrew Morton
2014-04-30T21:01:00Z

On Wed, 30 Apr 2014 16:42:55 -0400 Rik van Riel <riel@redhat.com> wrote:

> On Wed, 30 Apr 2014 13:13:53 -0700
> Andrew Morton <akpm@linux-foundation.org> wrote:
>
> > This was a consequence of 64->32 truncation and it can't happen any
> > more, can it?
>
> Andrew, this is cleaner indeed :)

I'm starting to get worried about 32-bit wraparound in the patch
version number ;)

> Masayoshi-san, does the bug still happen with this version, or does
> this fix the problem?
>

We could put something like

if (WARN_ON_ONCE(setpoint == limit))
setpoint--;

in there if we're not sure. But it's better to be sure!