* Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> [230814 15:15]:
> On Mon, 14 Aug 2023 16:54:01 +0200 Jann Horn <jannh@xxxxxxxxxx> wrote:
>
> > > @@ -403,6 +403,8 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
> > >
> > > vma_iter_store(&vmi, vma);
> > >
> > > + vma_start_write(vma);
> > > +
> > > if (vma->vm_file) {
> > > mapping = vma->vm_file->f_mapping;
> > > i_mmap_lock_write(mapping);
> >
> > The "vma_start_write()" has to be ordered before the
> > "vma_iter_store(&vmi, vma)".
>
> Thanks. This?
Yes, this looks good.
>
>
> --- a/mm/mmap.c~mm-always-lock-new-vma-before-inserting-into-vma-tree-fix
> +++ a/mm/mmap.c
> @@ -401,10 +401,10 @@ static int vma_link(struct mm_struct *mm
> if (vma_iter_prealloc(&vmi, vma))
> return -ENOMEM;
>
> - vma_iter_store(&vmi, vma);
> -
> vma_start_write(vma);
>
> + vma_iter_store(&vmi, vma);
> +
> if (vma->vm_file) {
> mapping = vma->vm_file->f_mapping;
> i_mmap_lock_write(mapping);
> _
>
