Re: [PATCH mm-unstable v1 1/5] mm: consolidate anonymous folio PTE mapping into helpers

David Hildenbrand (Arm)
2026-02-12T20:13:43Z

On 2/12/26 21:06, Zi Yan wrote:
> <snip>
>
>>>
>>>
>>> OK, this becomes maybe_mkwrite(pte_mkdirty(entry), vma).
>>
>> Yes, upon further investigation this does seem to slightly change the behavior.
>
> I did not notice it when I was reviewing it. ;)
>
>>
>> pte_mkdirty() is now being called unconditionally from the VM_WRITE
>> flag. I noticed other callers in the kernel doing this too.
>>
>> Is it ok to leave the pte_mkdirty() or should I go back to using
>> pte_mkwrite with the conditional guarding both mkwrite and mkdirty?
>
>
> IMHO, it is better to use the conditional guarding way.
> We reach here when userspace reads an address (VM_WRITE is not set)
> and no zero page is used. Using maybe_mkwrite(pte_mkdirty(entry), vma)
> means we will get a dirty PTE pointing to the allocated page but user
> only reads from it.

In general, it's best to not perform any such changes as part of a
bigger patch. :)

--
Cheers,

David