MEMCG_LRU_TAIL
else if (op == MEMCG_LRU_TAIL)
seg = MEMCG_LRU_TAIL;
if (READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_TAIL)
return MEMCG_LRU_TAIL;
return READ_ONCE(lruvec->lrugen.seg) != MEMCG_LRU_TAIL ?
MEMCG_LRU_TAIL : MEMCG_LRU_YOUNG;