The Linux kernel internally uses the common C convention in which negative numbers are errors (-ENOMEM and so on) while positive numbers (and zero) are successf

The Linux kernel internally uses the common C convention in which negative numbers are errors (-ENOMEM and so on) while positive numbers (and zero) are successful values. (Some parts of the kernel use a related convention in which values within the "last page" of the address space, that is, -4096 to -1 inclusive, are errors, while other values are valid memory addresses; there are macros to convert between both conventions.)