selftests/vm: add test for mlock() when areas are intersected

This patch adds mlock() test for multiple invocation on the same address
area, and verify it doesn't mess the rlimit mlock limitation.

Link: http://lkml.kernel.org/r/1472554781-9835-5-git-send-email-wei.guo.simon@gmail.com
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Cc: Alexey Klimov <klimov.linux@gmail.com>
Cc: Eric B Munson <emunson@akamai.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Simon Guo <wei.guo.simon@gmail.com>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 81 insertions, 0 deletions

diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore
index a937a9d..142c565 100644
--- a/tools/testing/selftests/vm/.gitignore
+++ b/tools/testing/selftests/vm/.gitignore
@@ -7,3 +7,4 @@ mlock2-tests
 on-fault-limit
 transhuge-stress
 userfaultfd
+mlock-intersect-test
diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
index e4bb1de..a0412a8 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -10,6 +10,7 @@ BINARIES += on-fault-limit
 BINARIES += thuge-gen
 BINARIES += transhuge-stress
 BINARIES += userfaultfd
+BINARIES += mlock-intersect-test
 
 all: $(BINARIES)
 %: %.c
@@ -17,6 +18,9 @@ all: $(BINARIES)
 userfaultfd: userfaultfd.c ../../../../usr/include/linux/kernel.h
 	$(CC) $(CFLAGS) -O2 -o $@ $< -lpthread
 
+mlock-intersect-test: mlock-intersect-test.c
+	$(CC) $(CFLAGS) -o $@ $< -lcap
+
 ../../../../usr/include/linux/kernel.h:
 	make -C ../../../.. headers_install
 
diff --git a/tools/testing/selftests/vm/mlock-intersect-test.c b/tools/testing/selftests/vm/mlock-intersect-test.c
new file mode 100644
index 0000000..f78e68a
--- /dev/null
+++ b/tools/testing/selftests/vm/mlock-intersect-test.c
@@ -0,0 +1,76 @@
+/*
+ * It tests the duplicate mlock result:
+ * - the ulimit of lock page is 64k
+ * - allocate address area 64k starting from p
+ * - mlock   [p -- p + 30k]
+ * - Then mlock address  [ p -- p + 40k ]
+ *
+ * It should succeed since totally we locked
+ * 40k < 64k limitation.
+ *
+ * It should not be run with CAP_IPC_LOCK.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/resource.h>
+#include <sys/capability.h>
+#include <sys/mman.h>
+#include "mlock2.h"
+
+int main(int argc, char **argv)
+{
+	struct rlimit new;
+	char *p = NULL;
+	cap_t cap = cap_init();
+	int i;
+
+	/* drop capabilities including CAP_IPC_LOCK */
+	if (cap_set_proc(cap))
+		return -1;
+
+	/* set mlock limits to 64k */
+	new.rlim_cur = 65536;
+	new.rlim_max = 65536;
+	setrlimit(RLIMIT_MEMLOCK, &new);
+
+	/* test VM_LOCK */
+	p = malloc(1024 * 64);
+	if (mlock(p, 1024 * 30)) {
+		printf("mlock() 30k return failure.\n");
+		return -1;
+	}
+	for (i = 0; i < 10; i++) {
+		if (mlock(p, 1024 * 40)) {
+			printf("mlock() #%d 40k returns failure.\n", i);
+			return -1;
+		}
+	}
+	for (i = 0; i < 10; i++) {
+		if (mlock2_(p, 1024 * 40, MLOCK_ONFAULT)) {
+			printf("mlock2_() #%d 40k returns failure.\n", i);
+			return -1;
+		}
+	}
+	free(p);
+
+	/* Test VM_LOCKONFAULT */
+	p = malloc(1024 * 64);
+	if (mlock2_(p, 1024 * 30, MLOCK_ONFAULT)) {
+		printf("mlock2_() 30k return failure.\n");
+		return -1;
+	}
+	for (i = 0; i < 10; i++) {
+		if (mlock2_(p, 1024 * 40, MLOCK_ONFAULT)) {
+			printf("mlock2_() #%d 40k returns failure.\n", i);
+			return -1;
+		}
+	}
+	for (i = 0; i < 10; i++) {
+		if (mlock(p, 1024 * 40)) {
+			printf("mlock() #%d 40k returns failure.\n", i);
+			return -1;
+		}
+	}
+	return 0;
+}