Re: Linux source code: malloc.c

["Steven Smith" <sos22@cam.ac.uk>]

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> > > Where can I see the implementation of free() and malloc() in Linux
> > > source code? I am not able to locate the file malloc.c.
> > That's because malloc() isn't in Linux-the-kernel: it's in glibc.
> > The file you're looking for is malloc/malloc.c in the glibc tarball.
> Except the kernel implements its own "kmalloc", which if I'm not wrong is called
> upon by libc's malloc
Um, sort of... the kernel does implement a function kmalloc, but it's
not the same as the user-exposed one.  For a start, memory allocated by
kmalloc is only accessible from kernel space, rather than user programs.

The kernel does provide two main primitives for userspace programs to
allocated memory: mmap and brk.  These are both fairly limited,
though.  mmap can only cope with multiples of the page size (4096
bytes on x86), while brk enforces a stack-like discipline.

sys_mmap and sys_brk do call upon kmalloc themselves, though.

Steven.


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