On Wed, Jul 17, 2024 at 04:06:58PM GMT, Liam R. Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
>
> Adding support for a NULL vma means the init_vma_munmap() can be
> initialized for a less error-prone process when calling
> vms_complete_munmap_vmas() later on.
>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> ---
> mm/mmap.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index a1544a68558e..722bcced0499 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -517,9 +517,14 @@ static inline void init_vma_munmap(struct vma_munmap_struct *vms,
> {
> vms->vmi = vmi;
> vms->vma = vma;
> - vms->mm = vma->vm_mm;
> - vms->start = start;
> - vms->end = end;
> + if (vma) {
> + vms->mm = vma->vm_mm;
> + vms->start = start;
> + vms->end = end;
> + } else {
> + vms->mm = NULL;
> + vms->start = vms->end = 0;
> + }
> vms->unlock = unlock;
> vms->uf = uf;
> vms->vma_count = 0;
> @@ -2950,11 +2955,11 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>
> /* Find the first overlapping VMA */
> vma = vma_find(&vmi, end);
> + init_vma_munmap(&vms, &vmi, vma, addr, end, uf, /* unlock = */ false);
> if (vma) {
> mt_init_flags(&mt_detach, vmi.mas.tree->ma_flags & MT_FLAGS_LOCK_MASK);
> mt_on_stack(mt_detach);
> mas_init(&mas_detach, &mt_detach, /* addr = */ 0);
> - init_vma_munmap(&vms, &vmi, vma, addr, end, uf, /* unlock = */ false);
> /* Prepare to unmap any existing mapping in the area */
> if (vms_gather_munmap_vmas(&vms, &mas_detach))
> return -ENOMEM;
> --
> 2.43.0
>
LGTM,
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
