On Tue, Jan 19, 2021 at 07:08:32PM +0100, Bodo Stroesser wrote: > On 19.01.21 19:03, Jason Gunthorpe wrote: > > On Tue, Jan 19, 2021 at 06:24:49PM +0100, Bodo Stroesser wrote: > > > > > > I had a second look into math.h, but I don't find any reason why round_up > > > could overflow. Can you give a hint please? > > > > #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1) > > ^^^^^ > > > > That +1 can overflow > > But that would be a unsigned long long overflow. I considered this to > not be relevant. Why not? It still makes nents 0 and still causes a bad bug Jason