selftest: add simple test for soft-dirty bit

It creates a mapping of 3 pages and checks that reads, writes and
clear-refs result in present and soft-dirt bits reported from pagemap2
set as expected.

[akpm@linux-foundation.org: alphasort the Makefile TARGETS to reduce rejects]
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 3cc0ad7..5eff5f7 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -1,10 +1,11 @@
 TARGETS = breakpoints
-TARGETS += kcmp
-TARGETS += mqueue
-TARGETS += vm
 TARGETS += cpu-hotplug
-TARGETS += memory-hotplug
 TARGETS += efivarfs
+TARGETS += kcmp
+TARGETS += memory-hotplug
+TARGETS += mqueue
+TARGETS += soft-dirty
+TARGETS += vm
 
 all:
 	for TARGET in $(TARGETS); do \