On Tue, Oct 14, 2025 at 04:38:38PM +0200, David Hildenbrand wrote:

On 14.10.25 16:32, Matthew Wilcox wrote:

quoted

On Tue, Oct 14, 2025 at 02:59:30PM +0200, David Hildenbrand wrote:

quoted

quoted

As commit 349994cf61e6 mentioned, we don't support partially mapped PUD-sized
folio yet.

We do support partially mapped PUD-sized folios I think, but not anonymous
PUD-sized folios.

I don't think so?  The only mechanism I know of to allocate PUD-sized
chunks of memory is hugetlb, and that doesn't permit partial mappings.

Greetings from the latest DAX rework :)

After a re-think, do you think it's better to align the behavior between
CONFIG_NO_PAGE_MAPCOUNT and CONFIG_PAGE_MAPCOUNT?

It looks we treat a PUD-sized folio partially_mapped if CONFIG_NO_PAGE_MAPCOUNT,
but !partially_mapped if CONFIG_PAGE_MAPCOUNT, if my understanding is correct.

-- 
Cheers

David / dhildenb

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