On Tue, 29 Apr 2014 18:48:11 -0400 Rik van Riel <[email protected]> wrote:
> On 04/29/2014 06:39 PM, Andrew Morton wrote: > > On Tue, 29 Apr 2014 15:19:10 -0400 Rik van Riel <[email protected]> wrote: > > > >> It is possible for "limit - setpoint + 1" to equal zero, leading to a > >> divide by zero error. Blindly adding 1 to "limit - setpoint" is not > >> working, so we need to actually test the divisor before calling div64. > >> > >> ... > >> > >> --- a/mm/page-writeback.c > >> +++ b/mm/page-writeback.c > >> @@ -597,11 +597,16 @@ static inline long long pos_ratio_polynom(unsigned > >> long setpoint, > >> unsigned long dirty, > >> unsigned long limit) > >> { > >> + unsigned int divisor; > > > > I'm thinking this would be better as a ulong so I don't have to worry > > my pretty head over truncation things? > > I looked at div_*64, and the second argument is a 32 bit > variable. I guess a long would be ok, since if we are > dividing by more than 4 billion we don't really care :) > > static inline s64 div_s64(s64 dividend, s32 divisor) ah, good point. Switching to ulong is perhaps a bit misleading then. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
