1999-09-19 Roland McGrath <roland@baalperazim.frob.com>

	* sysdeps/mach/hurd/brk.c (_hurd_set_brk): Deallocate and reallocate
	pages rather than just reprotecting them.  This way we don't hold on
	to the backing space.

diff --git a/sysdeps/mach/hurd/brk.c b/sysdeps/mach/hurd/brk.c
index 3a5ed54..c5d09a3 100644 (file)
--- a/sysdeps/mach/hurd/brk.c
+++ b/sysdeps/mach/hurd/brk.c
@@ -72,9 +72,18 @@ _hurd_set_brk (vm_address_t addr)
   if (pagend <= pagebrk)
     {
       if (pagend < pagebrk)
-       /* Make that memory inaccessible.  */
-       __vm_protect (__mach_task_self (), pagend, pagebrk - pagend,
-                     0, VM_PROT_NONE);
+       {
+         /* XXX wish this were atomic... */
+         /* First deallocate the memory to release its backing space.  */
+         __vm_deallocate (__mach_task_self (), pagend, pagebrk - pagend);
+         /* Now reallocate it with no access allowed.  */
+         err = __vm_map (__mach_task_self (),
+                         &pagend, _hurd_data_end - pagend,
+                         0, 0, MACH_PORT_NULL, 0, 0,
+                         0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE,
+                         VM_INHERIT_COPY);
+         /* XXX what if error? */
+       }
       _hurd_brk = addr;
       return 0;
     }