1 files changed, 12 insertions, 1 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 4389696fba0e..5d1839a9148d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1324,8 +1324,19 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
                 goto put_anon;
 
         if (page_mapped(hpage)) {
+                struct address_space *mapping = page_mapping(hpage);
+
+                /*
+                 * try_to_unmap could potentially call huge_pmd_unshare.
+                 * Because of this, take semaphore in write mode here and
+                 * set TTU_RMAP_LOCKED to let lower levels know we have
+                 * taken the lock.
+                 */
+                i_mmap_lock_write(mapping);
                 try_to_unmap(hpage,
-                        TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
+                        TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS|
+                        TTU_RMAP_LOCKED);
+                i_mmap_unlock_write(mapping);
                 page_was_mapped = 1;
         }