[PATCH next] mm/thp: fix collapse_file()'s try_to_unmap(folio,)

[Hugh Dickins <hughd@google.com>]

The foliation of THP collapse_file()'s call to try_to_unmap() is
currently wrong, crashing on a test in rmap_walk() when xas_next()
delivered a value (after which page has been loaded independently).

Fixes: c3b522d9a698 ("mm/rmap: Convert try_to_unmap() to take a folio")
Signed-off-by: Hugh Dickins <hughd@google.com>
---
Please just fold in if you agree.

 mm/khugepaged.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- mmotm/mm/khugepaged.c
+++ linux/mm/khugepaged.c
@@ -1824,7 +1824,8 @@ static void collapse_file(struct mm_stru
 		}
 
 		if (page_mapped(page))
-			try_to_unmap(folio, TTU_IGNORE_MLOCK | TTU_BATCH_FLUSH);
+			try_to_unmap(page_folio(page),
+				     TTU_IGNORE_MLOCK | TTU_BATCH_FLUSH);
 
 		xas_lock_irq(&xas);
 		xas_set(&xas, index);