Fix fork()-related lock rank ordering reversals.

test/unit/fork.c

@@ -0,0 +1,39 @@
+#include "test/jemalloc_test.h"
+
+#include <sys/wait.h>
+
+TEST_BEGIN(test_fork)
+{
+	void *p;
+	pid_t pid;
+
+	p = malloc(1);
+	assert_ptr_not_null(p, "Unexpected malloc() failure");
+
+	pid = fork();
+	if (pid == -1) {
+		/* Error. */
+		test_fail("Unexpected fork() failure");
+	} else if (pid == 0) {
+		/* Child. */
+		exit(0);
+	} else {
+		int status;
+
+		/* Parent. */
+		free(p);
+		do {
+			if (waitpid(pid, &status, 0) == -1)
+				test_fail("Unexpected waitpid() failure");
+		} while (!WIFEXITED(status) && !WIFSIGNALED(status));
+	}
+}
+TEST_END
+
+int
+main(void)
+{
+
+	return (test(
+	    test_fork));
+}