Re: [PATCH v1 16/16] mm/memory: support VM_MIXEDMAP in zap_special_vma_range()

Lorenzo Stoakes (Oracle)
2026-03-06T21:18:53Z

On Fri, Feb 27, 2026 at 09:08:47PM +0100, David Hildenbrand (Arm) wrote:
> There is demand for also zapping page table entries by drivers in
> VM_MIXEDMAP VMAs[1].
>
> Nothing really speaks against supporting VM_MIXEDMAP for driver use. We
> just don't want arbitrary drivers to zap in ordinary (non-special) VMAs.
>
> [1] https://lore.kernel.org/r/aYSKyr7StGpGKNqW@google.com

Dude, you have to start your indices with 0 what kind of programmer are
you? ;)

>
> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

Agreed that there's no reason not to allow this, so LGTM and:

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

Thanks for this series overall, very nice cleanup and I was frustra^Whappy
to see that there was nothing major or really of note to comment on here, a
rare occurrence in review :)

> ---
> mm/memory.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index f3b7b7e16138..3fe30dc2f179 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2239,13 +2239,13 @@ void zap_vma_range(struct vm_area_struct *vma, unsigned long address,
> * @size: number of bytes to zap
> *
> * This function does nothing when the provided address range is not fully
> - * contained in @vma, or when the @vma is not VM_PFNMAP.
> + * contained in @vma, or when the @vma is not VM_PFNMAP or VM_MIXEDMAP.
> */
> void zap_special_vma_range(struct vm_area_struct *vma, unsigned long address,
> unsigned long size)
> {
> if (!range_in_vma(vma, address, address + size) ||
> - !(vma->vm_flags & VM_PFNMAP))
> + !(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)))
> return;
>
> zap_vma_range(vma, address, size);
> --
> 2.43.0
>

Cheers, Lorenzo