But the question mark was coz I was wondering if there's some process global lock that would prevent it. I think I was thinking of the mmap lock. But this was

But the question mark was coz I was wondering if there's some process global lock that would prevent it. I think I was thinking of the mmap lock. But this was a dumb question mark, this lock isn't just randomly taken when threads enter syscalls. So yeah this is indeed another reason why copy_from_user etc is needed.