quoted

@@ -3377,7 +3377,7 @@ void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
   		pgoff_t nr, bool even_cows)
   {
   	pgoff_t	first_index = start, last_index = start + nr - 1;
-	struct zap_details details = { };
+	struct zap_details details = { .zap_flags = ZAP_FLAG_SKIP_SWAP };
   
   	details.zap_mapping = even_cows ? NULL : mapping;
   	if (last_index < first_index)

I think what would really help is to add a high-level description what
unmap_mapping_page() vs. unmap_mapping_pages() really does, and what the
expectations/use cases are. The names are just way too similar ...

aaaaand staring only at this patch I missed that we have nice 
descriptions already :)
-- 
Thanks,

David / dhildenb