fs/proc/task_mmu: convert pagemap_hugetlb_range() to work on folios

Patch series "fs/proc/task_mmu: convert hugetlb functions to work on folis".

Let's convert two more functions, getting rid of two more page_mapcount()
calls.


This patch (of 2):

Let's get rid of another page_mapcount() check and simply use
folio_likely_mapped_shared(), which is precise for hugetlb folios.

While at it, also check for PMD table sharing, like we do in
smaps_hugetlb_range().

No functional change intended, except that we would now detect hugetlb
folios shared via PMD table sharing correctly.

Link: https://lkml.kernel.org/r/20240417092313.753919-1-david@redhat.com
Link: https://lkml.kernel.org/r/20240417092313.753919-2-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/proc/task_mmu.c

@@ -1578,12 +1578,13 @@ static int pagemap_hugetlb_range(pte_t *ptep, unsigned long hmask,
 
 	pte = huge_ptep_get(ptep);
 	if (pte_present(pte)) {
-		struct page *page = pte_page(pte);
+		struct folio *folio = page_folio(pte_page(pte));
 
-		if (!PageAnon(page))
+		if (!folio_test_anon(folio))
 			flags |= PM_FILE;
 
-		if (page_mapcount(page) == 1)
+		if (!folio_likely_mapped_shared(folio) &&
+		    !hugetlb_pmd_shared(ptep))
 			flags |= PM_MMAP_EXCLUSIVE;
 
 		if (huge_pte_uffd_wp(pte))