mm/khugepaged: clean up refcount check using folio_expected_ref_count()

Use folio_expected_ref_count() instead of open-coded logic in
is_refcount_suitable().  This avoids code duplication and improves
clarity.

Drop is_refcount_suitable() as it is no longer needed.

Link: https://lkml.kernel.org/r/20250526182818.37978-2-shivankg@amd.com
Signed-off-by: Shivank Garg <shivankg@amd.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: Fengwei Yin <fengwei.yin@intel.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 7731a162a1a7a4bbc2343bc8c90315a360eac4e0..15203ea7d0073da659f5fd41a5bcb6ff077148cf 100644 (file)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -548,19 +548,6 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte,
        }
 }
 
-static bool is_refcount_suitable(struct folio *folio)
-{
-       int expected_refcount = folio_mapcount(folio);
-
-       if (!folio_test_anon(folio) || folio_test_swapcache(folio))
-               expected_refcount += folio_nr_pages(folio);
-
-       if (folio_test_private(folio))
-               expected_refcount++;
-
-       return folio_ref_count(folio) == expected_refcount;
-}
-
 static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
                                        unsigned long address,
                                        pte_t *pte,
@@ -652,7 +639,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
                 * but not from this process. The other process cannot write to
                 * the page, only trigger CoW.
                 */
-               if (!is_refcount_suitable(folio)) {
+               if (folio_expected_ref_count(folio) != folio_ref_count(folio)) {
                        folio_unlock(folio);
                        result = SCAN_PAGE_COUNT;
                        goto out;
@@ -1402,7 +1389,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
                 * has excessive GUP pins (i.e. 512).  Anyway the same check
                 * will be done again later the risk seems low.
                 */
-               if (!is_refcount_suitable(folio)) {
+               if (folio_expected_ref_count(folio) != folio_ref_count(folio)) {
                        result = SCAN_PAGE_COUNT;
                        goto out_unmap;
                }