Re: [PATCH v1 07/11] mm/huge_memory: convert split_huge_pages_pid() from follow_page() to folio_walk

[Ryan Roberts]

>>>> It's trying to split some pmd-mapped THPs then checking and finding that
>>>> they are not split. The split is requested via
>>>> /sys/kernel/debug/split_huge_pages, which I believe ends up in this function
>>>> you are modifying here. Although I'll admit that looking at the change,
>>>> there is nothing obviously wrong! Any ideas?
>>>
>>> Nothing jumps at me as well. Let me fire up the debugger :)
>>
>> Ah, very likely the can_split_folio() check expects a raised refcount
>> already.
> 
> Indeed, the following does the trick! Thanks Ryan, I could have sworn
> I ran that selftest as well.

Ahha! Thanks for sorting so quickly!