Re: Where could I find the definition of __vm_deallocate() called by __munmap()?

[ur bridge <urbridge@outlook.com>]

Thank you, Florian,

I tried to locate __vm_deallocate()’s definition in glibc by grep, and found only a hidden_proto in sysdeps/mach/include/mach-shortcuts-hidden, with no actual implementation.

Is its code included in glibc? If not, how could glibc be built from the source?

Given that __mmap() will call the syscall mmap(), I can understand only if __munmap() is a thin wrapper for syscall munmap(), but it calls __vm_deallocate(). How does this mismatch work? How could Hurd’s code touch the necessary structures (e.g. vma, managed by Linux kernel) to handle the unmapping?


Re: Where could I find the definition of __vm_deallocate() called by __munmap()?

* ur bridge via Libc-help:

> I’m reading the malloc.c code, and find that when __munmap() is called
> to free a mmapped chunk, the control flow will fall into
> sysdeps/mach/munmap.c, where __vm_deallocate() will be
> called. However, I cannot find its definition. Where could it be?

This is Hurd code.  For Linux, __munmap is indeed a thin system call
wrapper.

Thanks,
Florian