stress-vma: fix 32/64 bit address generation

The 64 bit address size check was incorrect, it always defaulted to
32 bits, so fix this. Also add better address generation for 32 and
64 bit addresses.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>

stress-vma.c

@@ -99,16 +99,32 @@ static void *stress_mmapaddr_get_addr(const stress_args_t *args)
 {
 	const uintptr_t mask = ~(((uintptr_t)args->page_size) - 1);
 	void *addr = NULL;
+	uintptr_t ui_addr;
 
 	while (stress_vma_continue(args)) {
 		int fd[2], err;
 		ssize_t ret;
 
-		if (sizeof(uintptr_t) >= 32) {
-			addr = (void *)(((uintptr_t)stress_mwc64modn(1ULL << 38)) & mask);
+		if (sizeof(uintptr_t) > 4) {
+			uint64_t page_63 = (stress_mwc64() << 12) & 0x7fffffffffffffffULL;
+
+			if (stress_mwc1()) {
+				ui_addr = stress_mwc64modn((1ULL << 38) - 1) | page_63;
+			} else {
+				ui_addr = (1ULL << 36) | page_63;
+			}
+			/* occassionally use 32 bit addr in 64 bit addr space */
+			if (stress_mwc8modn(5) == 0)
+				ui_addr &= 0x7fffffffUL;
 		} else {
-			addr = (void *)(((uintptr_t)stress_mwc32modn(1UL << 28)) & mask);
+			uint32_t page_31 = (stress_mwc32() << 12) & 0x7fffffffUL;
+
+			if (stress_mwc1())
+				ui_addr = stress_mwc32modn((1UL << 28) - 1) | page_31;
+			else
+				ui_addr = (1ULL << 20) | page_31;
 		}
+		addr = (void *)(ui_addr & mask);
 
 		if (pipe(fd) < 0)
 			return NULL;
@@ -383,8 +399,10 @@ static void *stress_vma_maps(void *ptr)
 		while (stress_vma_continue(args)) {
 			char buf[4096];
 
-			if (lseek(fd, 0, SEEK_SET) < 0)
+			if (lseek(fd, 0, SEEK_SET) < 0) {
+				pr_inf("lseek fail\n");
 				break;
+			}
 			while (read(fd, buf, sizeof(buf)) > 1)
 				;
 		}
@@ -455,6 +473,8 @@ static void stress_vma_loop(
 
 	do {
 		pid_t pid;
+
+		stress_mwc_reseed();
 		ctxt->data = stress_mmapaddr_get_addr(args);
 
 		pid = fork();
@@ -476,7 +496,7 @@ static void stress_vma_loop(
 							vma_funcs[i].vma_func, (void *)ctxt);
 				}
 			}
-			(void)sleep(15);
+			pause();
 			_exit(0);
 		}