diff --git a/mm/gup.c b/mm/gup.c
index 32d0e3ca7fbb..ad617e7f22f5 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -328,6 +328,13 @@ void unpin_user_pages(struct page **pages, unsigned long npages)
 {
 	unsigned long index;
 
+	/*
+	 * If this WARN_ON() fires, then the system *might* be leaking pages (by
+	 * leaving them pinned), but probably not. More likely, gup/pup returned
+	 * a hard -ERRNO error to the caller, who erroneously passed it here.
+	 */
+	if (WARN_ON(IS_ERR_VALUE(npages)))
+		return;
 	/*
 	 * TODO: this can be optimized for huge pages: if a series of pages is
 	 * physically contiguous and part of the same compound page, then a