v4.19.13 snapshot.
diff --git a/lib/lcm.c b/lib/lcm.c
new file mode 100644
index 0000000..03d7fcb
--- /dev/null
+++ b/lib/lcm.c
@@ -0,0 +1,25 @@
+#include <linux/compiler.h>
+#include <linux/gcd.h>
+#include <linux/export.h>
+#include <linux/lcm.h>
+
+/* Lowest common multiple */
+unsigned long lcm(unsigned long a, unsigned long b)
+{
+ if (a && b)
+ return (a / gcd(a, b)) * b;
+ else
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lcm);
+
+unsigned long lcm_not_zero(unsigned long a, unsigned long b)
+{
+ unsigned long l = lcm(a, b);
+
+ if (l)
+ return l;
+
+ return (b ? : a);
+}
+EXPORT_SYMBOL_GPL(lcm_not_zero);