1 files changed, 2 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 9cb27470fee9..deb679c31f2a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2426,6 +2426,8 @@ void unmap_mapping_range(struct address_space *mapping,
         if (details.last_index < details.first_index)
                 details.last_index = ULONG_MAX;
 
+
+        /* DAX uses i_mmap_lock to serialise file truncate vs page fault */
         i_mmap_lock_write(mapping);
         if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
                 unmap_mapping_range_tree(&mapping->i_mmap, &details);