Make stack size a multiple of the page size

Should fix #27

src/fellow_testenv.c

@@ -30,6 +30,7 @@
 #include <signal.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 #include "fellow_testenv.h"
 
@@ -54,8 +55,16 @@ static pthread_attr_t attr;
 static void __attribute__((constructor))
 attr_init(void)
 {
+	size_t pg, sz;
+
+	pg = (size_t)sysconf(_SC_PAGESIZE);
+	pg--;
+	sz = (size_t)64 * 1024;
+	sz += pg;
+	sz &= ~pg;
+
 	AZ(pthread_attr_init(&attr));
-	AZ(pthread_attr_setstacksize(&attr, (size_t)64 * 1024));
+	AZ(pthread_attr_setstacksize(&attr, sz));
 	AZ(pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED));
 }