- /*
- * Now page_cgroup is stable, but we cannot acquire mz->lru_lock
- * while holding it, because mem_cgroup_force_empty_list does the
- * reverse. Get a hold on the mem_cgroup before unlocking, so that
- * the zoneinfo remains stable, then take mz->lru_lock; then check
- * that page still points to pc and pc (even if freed and reassigned
- * to that same page meanwhile) still points to the same mem_cgroup.
- * Then we know mz still points to the right spinlock, so it's safe
- * to move_lists (page->page_cgroup might be reset while we do so, but
- * that doesn't matter: pc->page is stable till we drop mz->lru_lock).
- * We're being a little naughty not to try_lock_page_cgroup again
- * inside there, but we are safe, aren't we? Aren't we? Whistle...
- */