Unfortunately for kernel developers, allocating memory in the kernel is not as simple as allocating memory in user space. A number of factors contribute to the complication, among them: The kernel is ...

If your production Linux system is logging memory allocation failures, it might still be able to keep running. But developers want to keep an eye on which code can survive a shortage of memory.

Hm. The init process for CMA goes through normal memory allocation from the kernel regions, rejecting things not in the right zone, until it gets what it needs. The "magic" bit for the CMA ...