Re: [PATCH v3 40/40] mm/vma: introduce and use vma[_flags]_can_gup()

[Zi Yan]

On Thu Sep 17, 2026 at 12:22 PM EDT, Lorenzo Stoakes (ARM) wrote:
> GUP cannot be used for VMAs which set VMA_IO_BIT - because memory-mapped
> I/O must not be accessed on the user's behalf - or VMA_PFNMAP_BIT - because
> PFN maps have no folios which the kernel is permitted to access.
>
> Rather than keeping these checks open-coded, abstract them to
> vma_flags_can_gup() and its VMA wrapper vma_can_gup().
>
> A number of other places make the same check to decide whether a mapping
> can be populated or accessed as GUP would, so update those too.
>
> While here, drop a reference to 'special' and replace a use of the
> deprecated VMA flags API in vma_dump_size().
>
> No functional change intended.
>
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>
> ---
>  fs/coredump.c      |  4 ++--
>  include/linux/mm.h | 29 +++++++++++++++++++++++++++++
>  mm/gup.c           |  7 +++----
>  mm/hmm.c           |  3 +--
>  mm/memory.c        | 14 ++++++++------
>  mm/mempolicy.c     |  3 ++-
>  6 files changed, 45 insertions(+), 15 deletions(-)
>
Makes sense.

Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>

-- 
Best Regards,
Yan, Zi