Re: [PATCH] mm: don't ioremap COWed anon pages in generic_access_phys()

[David Hildenbrand (Arm)]

On 10/2/26 12:09, Lorenzo Stoakes (ARM) wrote:
> On Fri, Oct 02, 2026 at 12:04:27PM +0200, David Hildenbrand (Arm) wrote:
>> On 10/2/26 12:02, David Hildenbrand (Arm) wrote:
>>>
>>> Yes, I'll take care of it.
>>>
>>> [...]
>>>
>>> After sending this yesterday, I concluded that we can do this cleaner: just have
>>>
>>> bool normal_page;
>>>
>>> (naming suggestions?)
>>>
>>> that express that this is something refcounted with a struct page, like
>>> documented for vm_normal_page().
>>
>> Hmm, have to think about that once more, regarding VM_IO and if there are some
>> cases that would actually have to work in generic_access_phys().
> 
> Well, my series at least makes it easier to reason about VMA_IO_BIT!
> 
> Though not sure if it really touches PFN map cases specifically.

I'm more concerned about someone using this function on VM_MIXEDMAP | VM_IO with
a memory page that has a struct page but is actually not memory. So we could get
something that vm_normal_page() would flag but generic_access_phys() could
actually read ... I'll have to explore the generic_access_phys() users once more.

All way to complicated (and you series improves things).

-- 
Cheers,

David