[PATCH v2 03/14] mm: Convert vmf_insert_mixed() from using pte_devmap to pte_special

David Hildenbrand david at redhat.com
Wed Jun 18 19:31:02 AEST 2025


On 17.06.25 11:49, David Hildenbrand wrote:
> On 16.06.25 13:58, Alistair Popple wrote:
>> DAX no longer requires device PTEs as it always has a ZONE_DEVICE page
>> associated with the PTE that can be reference counted normally. Other users
>> of pte_devmap are drivers that set PFN_DEV when calling vmf_insert_mixed()
>> which ensures vm_normal_page() returns NULL for these entries.
>>
>> There is no reason to distinguish these pte_devmap users so in order to
>> free up a PTE bit use pte_special instead for entries created with
>> vmf_insert_mixed(). This will ensure vm_normal_page() will continue to
>> return NULL for these pages.
>>
>> Architectures that don't support pte_special also don't support pte_devmap
>> so those will continue to rely on pfn_valid() to determine if the page can
>> be mapped.
>>
>> Signed-off-by: Alistair Popple <apopple at nvidia.com>
>> Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>
>> Reviewed-by: Dan Williams <dan.j.williams at intel.com>
>> ---

As Andrew notes offlined, there is no content here. I sent this by mistake
after replying to patch#6 instead.

-- 
Cheers,

David / dhildenb



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