Re: [PATCH v3 25/40] mm/vma: enforce that only kernel-owned mappings may set VMA_IO_BIT

[Zi Yan]

On Thu Sep 17, 2026 at 12:22 PM EDT, Lorenzo Stoakes (ARM) wrote:
> It makes no sense for a mapping whose contents the kernel does not own to
> specify that the range is MMIO.
>
> Prior to this patch, all in-tree drivers which did so have been updated
> such that they are marked as kernel-owned. The check WARNs and fails the
> mmap for any out-of-tree driver that still sets VMA_IO_BIT without a kernel
> mapping.
>
> No functional change intended for in-tree code.
>
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>
> ---
>  mm/vma.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/mm/vma.c b/mm/vma.c
> index 1db8b218fe64..56a0cd154419 100644
> --- a/mm/vma.c
> +++ b/mm/vma.c
> @@ -2787,6 +2787,12 @@ static int mmap_validate_vma_flags(const vma_flags_t *flags)
>  		return -EINVAL;
>  #endif
>  
> +	if (!vma_flags_test_any(flags, VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT)) {

I thought why not just using vma_flags_is_kernel_owned(), then realize
that function is still checking VMA_IO_BIT. And you convert it in the
next patch.

LGTM.

Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>



-- 
Best Regards,
Yan, Zi