[PATCH 1/2] linux: prevent kernel choose addr by itself in mremap test

[Celeste Liu]

It's only guaranteed when MREMAP_FIXED was specified.
---
 sysdeps/unix/sysv/linux/tst-linux-mremap1.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/tst-linux-mremap1.c b/sysdeps/unix/sysv/linux/tst-linux-mremap1.c
index a5dce5aee4104b5c4a594daab4e5fda1c4080ab4..334ce2a30be1362233f6c20139f7a80213585d10 100644
--- a/sysdeps/unix/sysv/linux/tst-linux-mremap1.c
+++ b/sysdeps/unix/sysv/linux/tst-linux-mremap1.c
@@ -40,20 +40,21 @@ do_test (void)
 			    MAP_PRIVATE | MAP_ANONYMOUS, -1);
   xmunmap (fixed_addr, fixed_size);
 
-  /* Add 3 * pagesize.  */
-  fixed_size += 3 * old_size;
-
-  /* Test MREMAP_DONTUNMAP.  It should return FIXED_ADDR created above.  */
+  /* Test MREMAP_DONTUNMAP and MREMAP_FIXED. It should return address we
+     specified and the old address is still available  */
   char *new_addr = mremap (old_addr, old_size, new_size,
-			   MREMAP_DONTUNMAP | MREMAP_MAYMOVE,
+			   MREMAP_DONTUNMAP | MREMAP_MAYMOVE | MREMAP_FIXED,
 			   fixed_addr);
   if (new_addr == MAP_FAILED)
     return mremap_failure_exit (errno);
+  /* mremap should use the hint address. */
   TEST_VERIFY_EXIT (fixed_addr == new_addr);
-  old_addr[0] = 3;
-  old_addr[old_size - 1] = 4;
-  new_addr[0] = 1;
-  new_addr[new_size - 1] = 2;
+  /* Old range should be zero-filled. */
+  TEST_VERIFY_EXIT (old_addr[0] == 0);
+  TEST_VERIFY_EXIT (old_addr[old_size - 1] == 0);
+  /* New range should have the same bytes as the old one. */
+  TEST_VERIFY_EXIT (new_addr[0] == 1);
+  TEST_VERIFY_EXIT (new_addr[new_size - 1] == 2);
   xmunmap (new_addr, new_size);
   xmunmap (old_addr, old_size);
 

-- 
2.48.1