On Fri, Dec 06, 2024 at 12:24:54AM -0800, Hugh Dickins wrote: [...] > Another thing to understand: it's called before adding folio to list, > but after removing folio from list: when it can usefully compare whether > the emptiness of the list correctly matches lru_size 0. I think one source of confusion might be that this "emptiness" check has been removed by commit b4536f0c829c because of maintaining the list size per-zone and actual list is shared between zones of a node. > It cannot do so > when adding if you "simplify" it in the way that you did. >
