Re: [PATCH v3 3/4] mm: move dup_mmap() to mm

[Kees Cook <kees@kernel.org>]

On Mon, Apr 28, 2025 at 04:28:16PM +0100, Lorenzo Stoakes wrote:
> This is a key step in our being able to abstract and isolate VMA allocation
> and destruction logic.
> 
> This function is the last one where vm_area_free() and vm_area_dup() are
> directly referenced outside of mmap, so having this in mm allows us to
> isolate these.
> 
> We do the same for the nommu version which is substantially simpler.
> 
> We place the declaration for dup_mmap() in mm/internal.h and have
> kernel/fork.c import this in order to prevent improper use of this
> functionality elsewhere in the kernel.
> 
> While we're here, we remove the useless #ifdef CONFIG_MMU check around
> mmap_read_lock_maybe_expand() in mmap.c, mmap.c is compiled only if
> CONFIG_MMU is set.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

Reviewed-by: Kees Cook <kees@kernel.org>

-- 
Kees Cook