Nouveau - Mar 2023 - [PATCH] mm: Take a page reference when removing device exclusive entries

On 3/28/23 20:16, Matthew Wilcox wrote:
...
>> +	if (!get_page_unless_zero(vmf->page))
>> +		return 0;
> 
>  From a folio point of view: what the hell are you doing here?  Tail
> pages don't have individual refcounts; all the refcounts are actually
ohh, and I really should have caught that too. I plead spending too much
time recently in a somewhat more driver-centric mindset, and failing to
mentally shift gears properly for this case.

Sorry for missing that!

thanks,
-- 
John Hubbard
NVIDIA

John Hubbard <jhubbard at nvidia.com> writes:
> On 3/28/23 20:16, Matthew Wilcox wrote:
> ...
>>> +	if (!get_page_unless_zero(vmf->page))
>>> +		return 0;
>>  From a folio point of view: what the hell are you doing here?  Tail
>> pages don't have individual refcounts; all the refcounts are
actually
I had stuck with using the page because none of this stuff (yet)
supports compound pages anyway so we shouldn't see a tail page
anyway. But point taken, I admit I need to find some time to get a
deeper internalised understanding of folios than just s/page/folio.
> ohh, and I really should have caught that too. I plead spending too much
> time recently in a somewhat more driver-centric mindset, and failing to
> mentally shift gears properly for this case.
>
> Sorry for missing that!
>
> thanks,