@@ -925,19 +925,21 @@ void hmm_range_unregister(struct hmm_range *range)
{
struct hmm *hmm = range->hmm;
- /* Sanity check this really should not happen. */
- if (hmm == NULL || range->end <= range->start)
- return;
-
mutex_lock(&hmm->lock);
list_del_init(&range->list);
mutex_unlock(&hmm->lock);
/* Drop reference taken by hmm_range_register() */
- range->valid = false;
mmput(hmm->mm);
hmm_put(hmm);
- range->hmm = NULL;
+
+ /*
+ * The range is now invalid and the ref on the hmm is dropped, so
+ * poison the pointer. Leave other fields in place, for the caller's
+ * use.
+ */
+ range->valid = false;
+ memset(&range->hmm, POISON_INUSE, sizeof(range->hmm));
}
EXPORT_SYMBOL(hmm_range_unregister);