[PATCH 3/4] fix mm-add-and-use-find_lock_entries.patch

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

---
 mm/filemap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/filemap.c b/mm/filemap.c
index f3b448431bd4..7dfd7024d361 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1941,6 +1941,8 @@ unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
 				goto put;
 			if (page->mapping != mapping || PageWriteback(page))
 				goto unlock;
+			VM_BUG_ON_PAGE(!thp_contains(page, xas.xa_index),
+					page);
 		}
 		indices[pvec->nr] = xas.xa_index;
 		if (!pagevec_add(pvec, page))
-- 
2.29.2