Re: [PATCH v6 1/4] sgl_alloc_order: remove 4 GiB limit, sgl_free() warning

From: Jason Gunthorpe
Date: Tue Jan 19 2021 - 13:26:54 EST

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

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