Re: [PATCH v4 5/7] mm/khugepaged: Refactor the PTE state checks into a helper

[David Hildenbrand (Arm)]

On 8/12/26 21:39, Andrew Morton wrote:
> On Wed, 12 Aug 2026 10:40:08 +0200 "David Hildenbrand (Arm)" <david@xxxxxxxxxx> wrote:
> 
>> On 8/11/26 14:48, Nico Pache (Red Hat) wrote:
>>> For anonymous collapse, the collapse_scan_pmd() and
>>> __collapse_huge_page_isolate() functions share a large portion of their
>>> logic. These functions both check the state of the PTEs and verify the
>>> following:
>>> 	- max_pte_* values are not exceeded
>>> 	- uffd is not active
>>> 	- lazyfree properties
>>> 	- non-anonymous
>>>
>>> Merge these checks into a helper collapse_check_pte() to reduce code
>>> duplication. We also add a helper struct for this function called
>>> pte_check_context which allows us to pass the required parameters in a
>>> clean and elegant manner.
>>>
>>> A helper function is also introduced pte_check_fail() to provide a clean
>>> interface to set the pte_check_context failure results and return
>>> PTE_CHECK_FAIL state. This helps reduce code duplications across the new
>>> collapse_check_pte function.
>>>
>>> Two slight modifications are done to the original functionality. We now
>>> warn (instead of crash) if the anon test fails, and we leverage the
>>> vm_normal_folio function instead of page->folio, this should be
>>> functionally equivalent.
>>>
>>> No other functional changes intended.
>>>
>>> This patch is heavily based off work done by Lance Yang, but modified to
>>> deal with conflicts and feedback received during the review cycle [1].
>>>
>>
>> TL;DR, I think this patch here needs some more work, and we should not fast
>> track it at this point.
> 
> This has been floating around since July 6, so it's never been
> fast-tracked!

That's not what I mean. Stuff must be reviewed. Review capacity is limited. Some
stuff gets de-prioritized and reviewed later.

I managed to review it now, but concluded that it needs more work.

Instead of reworking the patch now to squeeze it in just before the merge
window, better to resend this single patch for the next cycle.

-- 
Cheers,

David