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-rw-r--r--mm/shmem.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 67afba5117f..dc12264f44f 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;