On 19.08.24 10:14, Baolin Wang wrote:
Expand the is_refcount_suitable() to support reference checks for file folios,
as preparation for supporting shmem mTHP collapse.
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index cdd1d8655a76..f11b4f172e61 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -549,8 +549,14 @@ static bool is_refcount_suitable(struct folio *folio)
int expected_refcount;
expected_refcount = folio_mapcount(folio);
- if (folio_test_swapcache(folio))
+ if (folio_test_anon(folio)) {
+ expected_refcount += folio_test_swapcache(folio) ?
+ folio_nr_pages(folio) : 0;
+ } else {
expected_refcount += folio_nr_pages(folio);
+ if (folio_test_private(folio))
+ expected_refcount++;
+ }
Alternatively, a bit neater
if (!folio_test_anon(folio) || folio_test_swapcache(folio))
expected_refcount += folio_nr_pages(folio);
if (folio_test_private(folio))
expected_refcount++;
The latter check should be fine even for anon folios (although always false)
return folio_ref_count(folio) == expected_refcount;
}
@@ -2285,8 +2291,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
break;
}
- if (folio_ref_count(folio) !=
- 1 + folio_mapcount(folio) + folio_test_private(folio)) {
The "1" is due to the pagecache, right? IIUC, we don't hold a raised
folio refcount as we do the xas_for_each().
--
Cheers,
David / dhildenb
