[RFC PATCH 01/11] mm: khugepaged: add khugepaged_max_ptes_none check in collapse_file()

[Baolin Wang <baolin.wang@linux.alibaba.com>]

Similar to the anonymous folios collapse, we should also check the 'khugepaged_max_ptes_none'
when trying to collapse shmem/file folios.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 mm/khugepaged.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 5a3386043f39..5d4493b77f3c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2125,6 +2125,13 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
 					}
 				}
 				nr_none++;
+
+				if (cc->is_khugepaged && nr_none > khugepaged_max_ptes_none) {
+					result = SCAN_EXCEED_NONE_PTE;
+					count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
+					goto xa_locked;
+				}
+
 				index++;
 				continue;
 			}
-- 
2.43.5