svn commit: r214953 - head/sys/vm

[Alan Cox]

Author: alc
Date: Sun Nov  7 21:40:34 2010
New Revision: 214953
URL: http://svn.freebsd.org/changeset/base/214953

Log:
  In case the stack size reaches its limit and its growth must be restricted,
  ensure that grow_amount is a multiple of the page size.  Otherwise, the
  kernel may crash in swap_reserve_by_uid() on HEAD and FreeBSD 8.x, and
  produce a core file with a missing stack on FreeBSD 7.x.
  
  Diagnosed and reported by: jilles
  Reviewed by:	kib
  MFC after:	1 week

Modified:
  head/sys/vm/vm_map.c

Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c	Sun Nov  7 20:56:41 2010	(r214952)
+++ head/sys/vm/vm_map.c	Sun Nov  7 21:40:34 2010	(r214953)
@@ -3338,7 +3338,8 @@ Retry:
 	if (grow_amount > stack_entry->avail_ssize)
 		grow_amount = stack_entry->avail_ssize;
 	if (is_procstack && (ctob(vm->vm_ssize) + grow_amount > stacklim)) {
-		grow_amount = stacklim - ctob(vm->vm_ssize);
+		grow_amount = trunc_page((vm_size_t)stacklim) -
+		    ctob(vm->vm_ssize);
 	}
 
 	/* If we would blow our VMEM resource limit, no go */