* 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.

2 files changed, 16 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index 9019d9b2ab..f7a6a6b003 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 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.
+
 	* hurd/hurdprio.c (_hurd_priority_which_map): Rearrange the code a bit.
 	Use __munmap instead of __vm_deallocate.
 
diff --git a/sysdeps/mach/hurd/brk.c b/sysdeps/mach/hurd/brk.c
index 3a5ed54247..c5d09a35ac 100644
--- 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;
     }