as reported by Jane Lv, mmap() returns an unsigned value (MAP_FAILED) upon error, so checking with <= 0 will not work
diff --git a/testcases/kernel/syscalls/writev/writev01.c b/testcases/kernel/syscalls/writev/writev01.c
index b4f3328..5f48fd0 100644
--- a/testcases/kernel/syscalls/writev/writev01.c
+++ b/testcases/kernel/syscalls/writev/writev01.c
@@ -482,7 +482,7 @@
 
         bad_addr = mmap(0, 1, PROT_NONE,
 			MAP_PRIVATE_EXCEPT_UCLINUX|MAP_ANONYMOUS, 0, 0);
-        if (bad_addr <= 0) {
+        if (bad_addr == MAP_FAILED) {
             printf("mmap failed\n");
         }
         wr_iovec[7].iov_base = bad_addr;