udmabuf: revert 'Add support for mapping hugepages (v4)'

This effectively reverts commit 16c243e99d33 ("udmabuf: Add support for
mapping hugepages (v4)").  Recently, Junxiao Chang found a BUG with page
map counting as described here [1].  This issue pointed out that the
udmabuf driver was making direct use of subpages of hugetlb pages.  This
is not a good idea, and no other mm code attempts such use.  In addition
to the mapcount issue, this also causes issues with hugetlb vmemmap
optimization and page poisoning.

For now, remove hugetlb support.

If udmabuf wants to be used on hugetlb mappings, it should be changed to
only use complete hugetlb pages.  This will require different alignment
and size requirements on the UDMABUF_CREATE API.

[1] https://lore.kernel.org/linux-mm/[email protected]/

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 16c243e99d33 ("udmabuf: Add support for mapping hugepages (v4)")
Signed-off-by: Mike Kravetz <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Acked-by: Vivek Kasireddy <[email protected]>
Acked-by: Gerd Hoffmann <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Dongwon Kim <[email protected]>
Cc: James Houghton <[email protected]>
Cc: Jerome Marchand <[email protected]>
Cc: Junxiao Chang <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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