zdtm: add test for prctl(PR_SET_THP_DISABLE)

Verify that enabling / disabling THP with prctl(PR_SET_THP_DISABLE) does
not change VMA flags
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>

test/zdtm/static/Makefile

@@ -208,6 +208,7 @@ TST_NOFILE	:=				\
 		netns_sub_veth			\
 		unlink_multiple_largefiles	\
 		config_inotify_irmap		\
+		thp_disable			\
 #		jobctl00			\
 
 ifneq ($(SRCARCH),arm)
@@ -500,6 +501,7 @@ mntns_shared_bind02:	CFLAGS += -DSHARED_BIND02
 mntns_root_bind02:	CFLAGS += -DROOT_BIND02
 maps02: get_smaps_bits.o
 mlock_setuid: get_smaps_bits.o
+thp_disable: get_smaps_bits.o
 inotify01:		CFLAGS += -DINOTIFY01
 unlink_fstat01+:	CFLAGS += -DUNLINK_OVER
 unlink_fstat04:		CFLAGS += -DUNLINK_FSTAT04

test/zdtm/static/thp_disable.c

+#include <sys/prctl.h>
+#include <sys/mman.h>
+#include "zdtmtst.h"
+#include "get_smaps_bits.h"
+
+#ifndef MADV_DONTDUMP
+#define MADV_DONTDUMP   16
+#endif
+
+const char *test_doc	= "Test prctl(THP_DISABLE) behaviour";
+const char *test_author	= "Mike Rapoport <rppt@linux.ibm.com>";
+
+#define MEM_SIZE (8192)
+
+int main(int argc, char **argv)
+{
+	unsigned long orig_flags = 0, new_flags = 0;
+	unsigned long orig_madv = 0, new_madv = 0;
+	void *area;
+
+	test_init(argc, argv);
+
+	area = mmap(NULL, MEM_SIZE, PROT_READ | PROT_WRITE,
+		    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (area == MAP_FAILED) {
+		pr_perror("mmap failed");
+		return -1;
+	}
+
+	test_msg("Fetch existing flags/adv\n");
+	if (get_smaps_bits((unsigned long)area, &orig_flags, &orig_madv))
+		return -1;
+
+	if (prctl(PR_SET_THP_DISABLE, 1, 0, 0, 0)) {
+		pr_perror("Disabling THP failed");
+		return -1;
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	if (prctl(PR_SET_THP_DISABLE, 0, 0, 0, 0)) {
+		pr_perror("Enabling THP failed");
+		return -1;
+	}
+
+	test_msg("Fetch restored flags/adv\n");
+	if (get_smaps_bits((unsigned long)area, &new_flags, &new_madv))
+		return -1;
+
+	if (orig_flags != new_flags) {
+		pr_err("Flags are changed %lx -> %lx\n", orig_flags, new_flags);
+		fail();
+		return -1;
+	}
+
+	if (orig_madv != new_madv) {
+		pr_err("Madvs are changed %lx -> %lx\n", orig_madv, new_madv);
+		fail();
+		return -1;
+	}
+
+	pass();
+
+	return 0;
+}