Close race between vmspace_exitfree() and exit1() and races between

vmspace_exitfree() and vmspace_free() which could result in the same
vmspace being freed twice.

Factor out part of exit1() into new function vmspace_exit().  Attach
to vmspace0 to allow old vmspace to be freed earlier.

Add new function, vmspace_acquire_ref(), for obtaining a vmspace
reference for a vmspace belonging to another process.  Avoid changing
vmspace refcount from 0 to 1 since that could also lead to the same
vmspace being freed twice.

Change vmtotal() and swapout_procs() to use vmspace_acquire_ref().

Reviewed by:	alc

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/vm/vm_extern.h b/sys/vm/vm_extern.h
index 08dba00..31f6e23 100644
--- a/sys/vm/vm_extern.h
+++ b/sys/vm/vm_extern.h
@@ -78,6 +78,8 @@ struct vmspace *vmspace_alloc(vm_offset_t, vm_offset_t);
 struct vmspace *vmspace_fork(struct vmspace *);
 void vmspace_exec(struct proc *, vm_offset_t, vm_offset_t);
 void vmspace_unshare(struct proc *);
+void vmspace_exit(struct thread *);
+struct vmspace *vmspace_acquire_ref(struct proc *);
 void vmspace_free(struct vmspace *);
 void vmspace_exitfree(struct proc *);
 void vnode_pager_setsize(struct vnode *, vm_ooffset_t);