[PATCH v2 03/17] mm/rmap: convert make_device_exclusive_range() to make_device_exclusive()

[David Hildenbrand]

On 17.02.25 01:01, Alistair Popple wrote:
> On Tue, Feb 11, 2025 at 09:33:54AM +0100, David Hildenbrand wrote:
>> On 11.02.25 06:00, Andrew Morton wrote:
>>> On Mon, 10 Feb 2025 20:37:45 +0100 David Hildenbrand <david at redhat.com> wrote:
>>>
>>>> The single "real" user in the tree of make_device_exclusive_range() always
>>>> requests making only a single address exclusive. The current implementation
>>>> is hard to fix for properly supporting anonymous THP / large folios and
>>>> for avoiding messing with rmap walks in weird ways.
>>>>
>>>> So let's always process a single address/page and return folio + page to
>>>> minimize page -> folio lookups. This is a preparation for further
>>>> changes.
>>>>
>>>> Reject any non-anonymous or hugetlb folios early, directly after GUP.
>>>>
>>>> While at it, extend the documentation of make_device_exclusive() to
>>>> clarify some things.
>>>
>>> x86_64 allmodconfig:
>>>
>>> drivers/gpu/drm/nouveau/nouveau_svm.c: In function 'nouveau_atomic_range_fault':
>>> drivers/gpu/drm/nouveau/nouveau_svm.c:612:68: error: 'folio' undeclared (first use in this function)
>>>     612 |                 page = make_device_exclusive(mm, start, drm->dev, &folio);
>>>         |                                                                    ^~~~~
>>> drivers/gpu/drm/nouveau/nouveau_svm.c:612:68: note: each undeclared identifier is reported only once for each function it appears in
>>
>> Ah! Because I was carrying on the same branch SVM fixes [1] that are
>> getting surprisingly little attention so far.
> 
> I believe this has been picked up in drm-misc-fixes now:
> 
> https://lore.kernel.org/dri-devel/Z69eloo_7LM6NneO@cassiopeiae/

Yes. Both trees should merge without conflicts. However, we can later 
get rid of the now-superfluous page_folio() that was required in the drm 
fix.

-- 
Cheers,

David / dhildenb