From 9eb9063e800090891b93fb7a74e0cb17dc579dc8 Mon Sep 17 00:00:00 2001
From: Richard Brooksby <rptb1+github@pobox.com>
Date: Wed, 10 Feb 2016 15:14:21 +0000
Subject: [PATCH] Ensuring landfinish doesn't try treecheck on unmapped memory.
  see <https://info.ravenbrook.com/mail/2016/02/10/14-42-20/0/>.

Copied from Perforce
 Change: 189121
 ServerID: perforce.ravenbrook.com
---
 mps/code/arena.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mps/code/arena.c b/mps/code/arena.c
index cf65402b4e6..738761aaa33 100644
--- a/mps/code/arena.c
+++ b/mps/code/arena.c
@@ -417,6 +417,11 @@ static void arenaFreeLandFinish(Arena arena)
   AVERT(Arena, arena);
   AVER(arena->hasFreeLand);
   
+  /* We're about to free the memory occupied by the free land, which
+     contains a CBS.  We want to make sure that LandFinish doesn't try
+     to check the CBS, so nuke it here.  TODO: LandReset? */
+  arena->freeLandStruct.splayTreeStruct.root = TreeEMPTY;
+
   /* The CBS block pool can't free its own memory via ArenaFree because
    * that would use the free land. */
   MFSFinishTracts(ArenaCBSBlockPool(arena), arenaMFSPageFreeVisitor,