[PATCH] fixup! mm: khugepaged: skip lazy-free folios

[Vernon Yang]

add comment about VM_DROPPABLE in code, make it clearer.

Signed-off-by: Vernon Yang <yanglincheng@xxxxxxxxxx>
---
 mm/khugepaged.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index c85d7381adb5..7c1642fbe394 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -575,6 +575,10 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma,
 		folio = page_folio(page);
 		VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio);

+		/*
+		 * If the vma has the VM_DROPPABLE flag, the collapse will
+		 * preserve the lazyfree property without needing to skip.
+		 */
 		if (cc->is_khugepaged && !(vma->vm_flags & VM_DROPPABLE) &&
 		    folio_test_lazyfree(folio) && !pte_dirty(pteval)) {
 			result = SCAN_PAGE_LAZYFREE;
@@ -1333,6 +1337,10 @@ static enum scan_result hpage_collapse_scan_pmd(struct mm_struct *mm,
 		}
 		folio = page_folio(page);

+		/*
+		 * If the vma has the VM_DROPPABLE flag, the collapse will
+		 * preserve the lazyfree property without needing to skip.
+		 */
 		if (cc->is_khugepaged && !(vma->vm_flags & VM_DROPPABLE) &&
 		    folio_test_lazyfree(folio) && !pte_dirty(pteval)) {
 			result = SCAN_PAGE_LAZYFREE;
--
2.51.0