+ /*
+ * Yes, ignore the return value from a GFP_ATOMIC mem_cgroup_charge.
+ * Failure is not an option here: we're now expected to remove every
+ * migration pte, and will cause crashes otherwise. Normally this
+ * is not an issue: mem_cgroup_prepare_migration bumped up the old
+ * page_cgroup count for safety, that's now attached to the new page,
+ * so this charge should just be another incrementation of the count,
+ * to keep in balance with rmap.c's mem_cgroup_uncharging. But if
+ * there's been a force_empty, those reference counts may no longer
+ * be reliable, and this charge can actually fail: oh well, we don't
+ * make the situation any worse by proceeding as if it had succeeded.
+ */
+ mem_cgroup_charge(new, mm, GFP_ATOMIC);
+