1 files changed, 14 insertions, 2 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 67afba5117f2..dc12264f44f5 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1145,8 +1145,20 @@ repeat:
                 if (!error) {
                         error = shmem_add_to_page_cache(page, mapping, index,
                                                 gfp, swp_to_radix_entry(swap));
-                        /* We already confirmed swap, and make no allocation */
-                        VM_BUG_ON(error);
+                        /*
+                         * We already confirmed swap under page lock, and make
+                         * no memory allocation here, so usually no possibility
+                         * of error; but free_swap_and_cache() only trylocks a
+                         * page, so it is just possible that the entry has been
+                         * truncated or holepunched since swap was confirmed.
+                         * shmem_undo_range() will have done some of the
+                         * unaccounting, now delete_from_swap_cache() will do
+                         * the rest (including mem_cgroup_uncharge_swapcache).
+                         * Reset swap.val? No, leave it so "failed" goes back to
+                         * "repeat": reading a hole and writing should succeed.
+                         */
+                        if (error)
+                                delete_from_swap_cache(page);
                 }
                 if (error)
                         goto failed;