On Wed, 27 Sep 2023, Paolo Bonzini wrote: > On 3/15/23 12:31, Kirill A. Shutemov wrote: > > MAX_ORDER currently defined as number of orders page allocator supports: > > user can ask buddy allocator for page order between 0 and MAX_ORDER-1. > > > > This definition is counter-intuitive and lead to number of bugs all over > > the kernel. > > > > Fix the bugs and then change the definition of MAX_ORDER to be > > inclusive: the range of orders user can ask from buddy allocator is > > 0..MAX_ORDER now. I think that exclusive MAX_ORDER is more intuitive in the C language - i.e. if you write "for (i = 0; i < MAX_ORDER; i++)", you are supposed to loop over all allowed values. If you declare an array "void *array[MAX_ORDER];" you are supposed to hold a value for each allowed order. Pascal has for loops and array dimensions with inclusive ranges - and it is more prone to off-by-one errors. Mikulas
