From 4063e3f74b0e452e26b7b5850619b4729ebbc1c3 Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Tue, 27 Jan 2026 09:38:36 +0100
Subject: [PATCH] Debug: Allocate pages scattered to help catching out-of-range
 bugs

---
 sysdep/unix/alloc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sysdep/unix/alloc.c b/sysdep/unix/alloc.c
index fcf855082..61c62b8f6 100644
--- a/sysdep/unix/alloc.c
+++ b/sysdep/unix/alloc.c
@@ -304,7 +304,12 @@ alloc_page(void)
   ajlog(ptr, NULL, 0, AJT_ALLOC_MMAP);
 
   for (int i=1; i<ALLOC_PAGES_AT_ONCE; i++)
-    free_page(ptr + page_size * i);
+#if DEBUGGING
+    if (i & 1)
+      mprotect(ptr + page_size * i, page_size, PROT_NONE);
+    else
+#endif
+      free_page(ptr + page_size * i);
 
   return ptr;
 #endif
-- 
2.47.3