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/[email protected]
Signed-off-by: Simon Guo <[email protected]>
Cc: Alexey Klimov <[email protected]>
Cc: Eric B Munson <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Simon Guo <[email protected]>
Cc: Thierry Reding <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: David Rientjes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

tools/testing/selftests/vm/.gitignore

@@ -7,3 +7,4 @@ mlock2-tests
 on-fault-limit
 transhuge-stress
 userfaultfd
+mlock-intersect-test

tools/testing/selftests/vm/Makefile

@@ -10,13 +10,17 @@ BINARIES += on-fault-limit
 BINARIES += thuge-gen
 BINARIES += transhuge-stress
 BINARIES += userfaultfd
+BINARIES += mlock-intersect-test
 
 all: $(BINARIES)
 %: %.c
 	$(CC) $(CFLAGS) -o $@ $^ -lrt
 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
 

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;
+}