css_is_dying
if (unlikely(wb_dying(wbc->wb) && !css_is_dying(wbc->wb->memcg_css)))
return memcg ? css_is_dying(&memcg->css) : false;
return css_is_online(&cs->css) && !css_is_dying(&cs->css);
VM_WARN_ON(!css_is_dying(&memcg->css));
if (!xas_load(&xas) && !css_is_dying(&pos->css)) {
} while (pos != memcg && !css_is_dying(&pos->css));