treewide: Add SPDX license identifier for more missed files

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have MODULE_LICENCE("GPL*") inside which was used in the initial
   scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 4 insertions, 0 deletions

diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index b6ac70616c32..1a7497d015b2 100644
--- a/mm/hwpoison-inject.c
+++ b/mm/hwpoison-inject.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /* Inject a hwpoison memory failure on a arbitrary pfn */
 #include <linux/module.h>
 #include <linux/debugfs.h>
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 1ffecd6333e5..99be52c5ca45 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * z3fold.c
  *
diff --git a/mm/zbud.c b/mm/zbud.c
index 28458f7d1e84..de5dd4ddaa82 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * zbud.c
  *
diff --git a/mm/zpool.c b/mm/zpool.c
index 01a771e304fa..a2dd9107857d 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * zpool memory storage api
  *