diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index a02179a0bded..6212fdd6761a 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -41,6 +41,7 @@ void set_page_writeback(struct page *page)
 }
 EXPORT_SYMBOL(set_page_writeback);
 
+/* Read the comment above folio_mark_dirty() regarding required locks! */
 bool set_page_dirty(struct page *page)
 {
 	return folio_mark_dirty(page_folio(page));
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 47495be68598..3a03e04b640c 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2763,6 +2763,11 @@ EXPORT_SYMBOL(folio_redirty_for_writepage);
  * in this folio.  Truncation will block on the page table lock as it
  * unmaps pages before removing the folio from its mapping.
  *
+ * .. DANGER::
+ *    Do not use this on a folio obtained from a function like
+ *    get_user_pages_fast() without holding appropriate locks; you might want to
+ *    use set_page_dirty_lock() or folio_mark_dirty_lock() instead.
+ *
  * Return: True if the folio was newly dirtied, false if it was already dirty.
  */
 bool folio_mark_dirty(struct folio *folio)