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

Jason Gunthorpe
2026-03-09T14:30:03Z

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

Are we sure about this?

This whole function seems like a hack to support drivers that are not
using an address_space.

I say that as one of the five driver authors who have made this
mistake.

The locking to safely use this function is really hard to do properly,
IDK if binder can shift to use address_space ??

Jason