> +#define BAD_PTR_STRING(x) (!(x) ? "(null)" : IS_ERR(x) ? "(err)" :
This is getting ridiculous.
Instead of simply printing a pointer as %08lx or %016llx, not only glibc
(null) stupidity is propagated but expanded and "improved".
I assure you reading 0000000000000000 is just as obvious as (null) and
reading fffffffffffffffa is just as good as -ENOMEM.
In fact printing with hex is more information. Maybe it is important
that buggy pointer is small value but it's value is lost.
Sure don't dereference a pointer for very small or very erry values
but print it without all the bell and whistles.