.

wcfs/client/wcfs.cpp

@@ -1105,6 +1105,10 @@ error _Mapping::unmap() {
     xerr::Contextf E("%s: %s: %s: unmap", v(f->wconn), v(f), v(mmap));
     etrace("");
 
+    // protect agains double unmap
+    if (mmap->mem_start == nil)
+        return nil;
+
     if (mmap->vma != nil) {
         mmap->_assertVMAOk();
         VMA *vma = mmap->vma;
@@ -1118,7 +1122,6 @@ error _Mapping::unmap() {
     error err = mm::unmap(mmap->mem_start, mmap->mem_stop - mmap->mem_start);
     mmap->mem_start = nil;
     mmap->mem_stop  = nil;
-    // XXX clear other fields?
 
     //f->_mmaps.remove(mmap);
     f->_mmaps.erase(