On 19.01.21 19:03, Jason Gunthorpe wrote:

On Tue, Jan 19, 2021 at 06:24:49PM +0100, Bodo Stroesser wrote:

quoted

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.

It looks like it would not be so bad to implement some
check_round_up_overflow() if people prefer

Jason