Re: [PATCH 1/1] mm/huge_memory: disallow raw PMD mappings of the huge zero page

[Kiryl Shutsemau]

On Thu, Sep 17, 2026 at 05:29:48PM +0200, David Hildenbrand (Arm) wrote:
> On 9/17/26 16:32, Kiryl Shutsemau wrote:
> > On Thu, Sep 17, 2026 at 08:10:10PM +0800, Lance Yang wrote:
> >> vm_mixed_zeropage_allowed() validates zeropage insertion into
> >> VM_MIXEDMAP VMAs. No in-tree user needs to insert the huge zero page
> >> through vmf_insert_pfn_pmd().
> >>
> >> Return VM_FAULT_SIGBUS if vmf_insert_pfn_pmd() is asked to map it.
> >>
> >> Link: https://lore.kernel.org/linux-mm/f76beaf8-351a-4b22-b362-a945a5e1af6a@xxxxxxxxxx/
> >> Suggested-by: Kiryl Shutsemau <kas@xxxxxxxxxx>
> >> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> >> Signed-off-by: Lance Yang <lance.yang@xxxxxxxxx>
> > 
> > The patch looks fine, but don't we want to cover the same for non-huge
> > zero page in vmf_insert_pfn_prot()?
> 
> Why would the zeropage be a problem in PFNMAP mapping?

Nothing enforces that it is read-only.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov