* Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx> [240705 15:40]:
> On Thu, Jul 04, 2024 at 02:27:10PM GMT, Liam R. Howlett wrote:
> > From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
> >
> > mmap_region is already passed sanitized addr and len, so change the
> > call to do_vmi_munmap() to do_vmi_align_munmap() and inline the other
> > checks.
> >
> > Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> > ---
> > mm/mmap.c | 20 ++++++++++++++------
> > 1 file changed, 14 insertions(+), 6 deletions(-)
> >
> > diff --git a/mm/mmap.c b/mm/mmap.c
> > index 8d9be791997a..e9858ca8bbd4 100644
> > --- a/mm/mmap.c
> > +++ b/mm/mmap.c
> > @@ -2937,12 +2937,20 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
> > return -ENOMEM;
> > }
> >
> > - /* Unmap any existing mapping in the area */
>
> This feels like an important comment, I know 'find the first overlapping
> VMA' below alludes to it but whenever I've read through this function this
> comment has actually been quite useful to know what the intent is.
>
> Could we reinstate it?
Ah, sure. I am going to have to move it around and it sort of loses its
meaning a bit once we gather and complete it (and not actually zero the
tree).. I'll try to keep it with the correct code block.
>
> > - error = do_vmi_munmap(&vmi, mm, addr, len, uf, false);
> > - if (error == -EPERM)
> > - return error;
> > - else if (error)
> > - return -ENOMEM;
> > +
> > + if (unlikely(!can_modify_mm(mm, addr, end)))
> > + return -EPERM;
> > +
> > + /* arch_unmap() might do unmaps itself. */
> > + arch_unmap(mm, addr, end);
> > +
> > + /* Find the first overlapping VMA */
> > + vma = vma_find(&vmi, end);
> > + if (vma) {
> > + if (do_vmi_align_munmap(&vmi, vma, mm, addr, end, uf, false))
> > + return -ENOMEM;
> > + vma = NULL;
> > + }
> >
> > /*
> > * Private writable mapping: check memory availability
> > --
> > 2.43.0
> >
> >
>
> Other than trivial point above, LGTM.
>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Thanks!
