On 2024/8/19 17:40, David Hildenbrand wrote:
On 19.08.24 10:14, Baolin Wang wrote:
Use the number of pages in the folio to check the reference count as
preparation for supporting shmem mTHP collapse.
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index f11b4f172e61..60d95f08610c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1994,7 +1994,7 @@ static int collapse_file(struct mm_struct *mm,
unsigned long addr,
/*
* We control three references to the folio:
^ "three" is wrong now.
Ah, good catch. Will change to '2 + nr_pages'.
* - we hold a pin on it;
- * - one reference from page cache;
+ * - nr_pages reference from page cache;
* - one from lru_isolate_folio;
* If those are the only references, then any new usage
* of the folio will have to fetch it from the page
@@ -2002,7 +2002,7 @@ static int collapse_file(struct mm_struct *mm,
unsigned long addr,
* truncate, so any new usage will be blocked until we
* unlock folio after collapse/during rollback.
*/
- if (folio_ref_count(folio) != 3) {
+ if (folio_ref_count(folio) != 2 + folio_nr_pages(folio)) {
result = SCAN_PAGE_COUNT;
xas_unlock_irq(&xas);
folio_putback_lru(folio);
@@ -2185,7 +2185,7 @@ static int collapse_file(struct mm_struct *mm,
unsigned long addr,
folio_clear_active(folio);
folio_clear_unevictable(folio);
folio_unlock(folio);
- folio_put_refs(folio, 3);
+ folio_put_refs(folio, 2 + folio_nr_pages(folio));
}
goto out;
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Thanks for reviewing.
