[PATCH] shmem_file_write double kunmap

Found by Simon Trimmer <simon@veritas.com>: shmem_file_write
failure path duplicates kunmap, causing oops holding kmap_lock.

mm/shmem.c

@@ -942,7 +942,6 @@ shmem_file_write(struct file *file,const char *buf,size_t count,loff_t *ppos)
 fail_write:
 	status = -EFAULT;
 	ClearPageUptodate(page);
-	kunmap(page);
 	goto unlock;
 }