On Wed, 30 Apr 2014 16:42:55 -0400 Rik van Riel <riel@xxxxxxxxxx> wrote: > On Wed, 30 Apr 2014 13:13:53 -0700 > Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > This was a consequence of 64->32 truncation and it can't happen any > > more, can it? > > Andrew, this is cleaner indeed :) > > Masayoshi-san, does the bug still happen with this version, or does > this fix the problem? I assumed we wanted a reported-by in there. > Subject: mm,writeback: fix divide by zero in pos_ratio_polynom > > It is possible for "limit - setpoint + 1" to equal zero, after > getting truncated to a 32 bit variable, and resulting in a divide > by zero error. > > Using the fully 64 bit divide functions avoids this problem. This isn't the whole story, is it? I added stuff: : Using the fully 64 bit divide functions avoids this problem. It also will : cause pos_ratio_polynom() to return the correct value when (setpoint - : limit) exceeds 2^32. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>